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@ -6,6 +6,8 @@ This section contains a summary of the 100 mistakes in the book. Meanwhile, it's
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<!-- TODO Include full excerpts -->
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<!-- TODO Include chapter-1.md -->
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## Code and Project Organization
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@ -142,6 +144,8 @@ The `any` type can be helpful if there is a genuine need for accepting or return
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**TL;DR**: Relying on generics and type parameters can prevent writing boilerplate code to factor out elements or behaviors. However, do not use type parameters prematurely, but only when you see a concrete need for them. Otherwise, they introduce unnecessary abstractions and complexity.
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<!-- TODO Include 9-generics.md file -->
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[Source code](https://github.com/teivah/100-go-mistakes/tree/master/src/02-code-project-organization/9-generics/main.go)
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### Not being aware of the possible problems with type embedding (#10)
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<a href="/9-generics/" class="md-nav__link">
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<span class="md-ellipsis">
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Being confused about when to use generics (#9)
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</span>
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</a>
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</li>
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<a href="/chapter-1/" class="md-nav__link">
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<span class="md-ellipsis">
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Go: Simple to learn but hard to master
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</a>
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100 Go Mistakes
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Concepts
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Common uses and misuses
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Go: Simple to learn but hard to master
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||||
|
||||
<h1 id="being-confused-about-when-to-use-generics-9">Being confused about when to use generics (#9)</h1>
|
||||
<p>Generics is a fresh addition to the language. In a nutshell, it allows writing code with types that can be specified later and instantiated when needed. However, it can be pretty easy to be confused about when to use generics and when not to. Throughout this post, we will describe the concept of generics in Go and then delve into common use and misuses.</p>
|
||||
<h2 id="concepts">Concepts</h2>
|
||||
<p>Consider the following function that extracts all the keys from a <code>map[string]int</code> type:</p>
|
||||
<pre><code class="language-go">func getKeys(m map[string]int) []string {
|
||||
var keys []string
|
||||
for k := range m {
|
||||
keys = append(keys, k)
|
||||
}
|
||||
return keys
|
||||
}
|
||||
</code></pre>
|
||||
<p>What if we would like to use a similar feature for another map type such as a <code>map[int]string</code>? Before generics, Go developers had a couple of options: using code generation, reflection, or duplicating code.</p>
|
||||
<p>For example, we could write two functions, one for each map type, or even try to extend <code>getKeys</code> to accept different map types:</p>
|
||||
<pre><code class="language-go">func getKeys(m any) ([]any, error) {
|
||||
switch t := m.(type) {
|
||||
default:
|
||||
return nil, fmt.Errorf("unknown type: %T", t)
|
||||
case map[string]int:
|
||||
var keys []any
|
||||
for k := range t {
|
||||
keys = append(keys, k)
|
||||
}
|
||||
return keys, nil
|
||||
case map[int]string:
|
||||
// Copy the extraction logic
|
||||
}
|
||||
}
|
||||
</code></pre>
|
||||
<p>We can start noticing a couple of issues:</p>
|
||||
<ul>
|
||||
<li>First, it increases boilerplate code. Indeed, whenever we want to add a case, it will require duplicating the <code>range</code> loop.</li>
|
||||
<li>Meanwhile, the function now accepts an empty interface, which means we are losing some of the benefits of Go being a typed language. Indeed, checking whether a type is supported is done at runtime instead of compile-time. Hence, we also need to return an error if the provided type is unknown.</li>
|
||||
<li>Last but not least, as the key type can be either <code>int</code> or <code>string</code>, we are obliged to return a slice of empty interfaces to factor out key types. This approach increases the effort on the caller-side as the client may also have to perform a type check of the keys or extra conversion.</li>
|
||||
</ul>
|
||||
<p>Thanks to generics, we can now refactor this code using type parameters.</p>
|
||||
<p>Type parameters are generic types we can use with functions and types. For example, the following function accepts a type parameter:</p>
|
||||
<pre><code class="language-go">func foo[T any](t T) {
|
||||
// ...
|
||||
}
|
||||
</code></pre>
|
||||
<p>When calling <code>foo</code>, we will pass a type argument of any type. Passing a type argument is called instantiation because the work is done at compile time which keeps type safety as part of the core language features and avoids runtime overheads.</p>
|
||||
<p>Let’s get back to the <code>getKeys</code> function and use type parameters to write a generic version that would accept any kind of map:</p>
|
||||
<pre><code class="language-go">func getKeys[K comparable, V any](m map[K]V) []K { <1>
|
||||
var keys []K <2>
|
||||
for k := range m {
|
||||
keys = append(keys, k)
|
||||
}
|
||||
return keys
|
||||
}
|
||||
</code></pre>
|
||||
<p>To handle the map, we defined two kinds of type parameters. First, the values can be of any type: <code>V any</code>. However, in Go, the map keys can’t be of any type. For example, we cannot use slices:</p>
|
||||
<pre><code class="language-go">var m map[[]byte]int
|
||||
</code></pre>
|
||||
<p>This code leads to a compilation error: <code>invalid map key type []byte</code>. Therefore, instead of accepting any key type, we are obliged to restrict type arguments so that the key type meets specific requirements. Here, being comparable (we can use <code>==</code> or <code>!=</code>). Hence, we defined <code>K</code> as <code>comparable</code> instead of <code>a``ny</code>.</p>
|
||||
<p>Restricting type arguments to match specific requirements is called a constraint. A constraint is an interface type that can contain:</p>
|
||||
<ul>
|
||||
<li>A set of behaviors (methods)</li>
|
||||
<li>But also arbitrary type</li>
|
||||
</ul>
|
||||
<p>Let’s see a concrete example for the latter. Imagine we don’t want to accept any <code>comparable</code> type for map key type. For instance, we would like to restrict it to either <code>int</code> or <code>string</code> types. We can define a custom constraint this way:</p>
|
||||
<pre><code class="language-go">type customConstraint interface {
|
||||
~int | ~string // Define a custom type that will restrict types to int and string
|
||||
}
|
||||
|
||||
// Change the type parameter K to be custom
|
||||
func getKeys[K customConstraint, V any](m map[K]V) []K {
|
||||
// Same implementation
|
||||
}
|
||||
</code></pre>
|
||||
<p>First, we define a <code>customConstraint</code> interface to restrict the types to be either <code>int</code> or <code>string</code> using the union operator <code>|</code> (we will discuss the use of <code>~</code> a bit later). Then, <code>K</code> is now a <code>customConstraint</code> instead of a <code>comparable</code> as before.</p>
|
||||
<p>Now, the signature of <code>getKeys</code> enforces that we can call it with a map of any value type, but the key type has to be an <code>int</code> or a <code>string</code>. For example, on the caller-side:</p>
|
||||
<pre><code class="language-go">m = map[string]int{
|
||||
"one": 1,
|
||||
"two": 2,
|
||||
"three": 3,
|
||||
}
|
||||
keys := getKeys(m)
|
||||
</code></pre>
|
||||
<p>Note that Go can infer that <code>getKeys</code> is called with a <code>string</code> type argument. The previous call was similar to this:</p>
|
||||
<pre><code class="language-go">keys := getKeys[string](m)
|
||||
</code></pre>
|
||||
<hr />
|
||||
<p><strong>NOTE:</strong> What’s the difference between a constraint using <code>~int</code> or <code>int</code>? Using <code>int</code> restricts it to that type, whereas <code>~int</code> restricts all the types whose underlying type is an <code>int</code>.</p>
|
||||
<p>To illustrate it, let’s imagine a constraint where we would like to restrict a type to any <code>int</code> type implementing the <code>String() string</code> method:</p>
|
||||
<pre><code class="language-go">type customConstraint interface {
|
||||
~int
|
||||
String() string
|
||||
}
|
||||
</code></pre>
|
||||
<p>Using this constraint will restrict type arguments to custom types like this one:</p>
|
||||
<pre><code class="language-cgo">type customInt int
|
||||
|
||||
func (i customInt) String() string {
|
||||
return strconv.Itoa(int(i))
|
||||
}
|
||||
</code></pre>
|
||||
<p>As <code>customInt</code> is an <code>int</code> and implements the <code>String() string</code> method, the <code>customInt</code> type satisfies the constraint defined.</p>
|
||||
<p>However, if we change the constraint to contain an <code>int</code> instead of an <code>~int</code>, using <code>customInt</code> would lead to a compilation error because the <code>int</code> type doesn’t implement <code>String() string</code>.</p>
|
||||
<hr />
|
||||
<p>Let’s also note the <code>constraints</code> package contains a set of common constraints such as <code>Signed</code> that includes all the signed integer types. Let’s ensure that a constraint doesn’t already exist in this package before creating a new one.</p>
|
||||
<p>So far, we have discussed examples using generics for functions. However, we can also use generics with data structures.</p>
|
||||
<p>For example, we will create a linked list containing values of any type. Meanwhile, we will write an <code>Add</code> method to append a node:</p>
|
||||
<pre><code class="language-cgo">type Node[T any] struct { // Use type parameter
|
||||
Val T
|
||||
next *Node[T]
|
||||
}
|
||||
|
||||
func (n *Node[T]) Add(next *Node[T]) { // Instantiate type receiver
|
||||
n.next = next
|
||||
}
|
||||
</code></pre>
|
||||
<p>We use type parameters to define <code>T</code> and use both fields in <code>Node</code>. Regarding the method, the receiver is instantiated. Indeed, because <code>Node</code> is generic, it has to follow also the type parameter defined.</p>
|
||||
<p>One last thing to note about type parameters: they can’t be used on methods, only on functions. For example, the following method wouldn’t compile:</p>
|
||||
<pre><code class="language-go">type Foo struct {}
|
||||
|
||||
func (Foo) bar[T any](t T) {}
|
||||
</code></pre>
|
||||
<pre><code>./main.go:29:15: methods cannot have type parameters
|
||||
</code></pre>
|
||||
<p>Now, let’s delve into concrete cases where we should and shouldn’t use generics.</p>
|
||||
<h2 id="common-uses-and-misuses">Common uses and misuses</h2>
|
||||
<p>So when are generics useful? Let’s discuss a couple of common uses where generics <strong>are</strong> recommended:</p>
|
||||
<ul>
|
||||
<li>Data structures. For example, we can use generics to factor out the element type if we implement a binary tree, a linked list, or a heap.</li>
|
||||
<li>Functions working with slices, maps, and channels of any type. For example, a function to merge two channels would work with any channel type. Hence, we could use type parameters to factor out the channel type:</li>
|
||||
</ul>
|
||||
<p><code>cgo
|
||||
func merge[T any](ch1, ch2 <-chan T) <-chan T {
|
||||
// ...
|
||||
}</code></p>
|
||||
<ul>
|
||||
<li>Meanwhile, instead of factoring out a type, we can factor out behaviors. For example, the <code>sort</code> package contains functions to sort different slice types such as <code>sort.Ints</code> or <code>sort.Float64s</code>. Using type parameters, we can factor out the sorting behaviors that rely on three methods, <code>Len</code>, <code>Less</code>, and <code>Swap</code>:</li>
|
||||
</ul>
|
||||
<p>```go
|
||||
type sliceFn[T any] struct { // Use type parameter
|
||||
s []T
|
||||
compare func(T, T) bool // Compare two T elements
|
||||
}</p>
|
||||
<p>func (s sliceFn[T]) Len() int { return len(s.s) }
|
||||
func (s sliceFn[T]) Less(i, j int) bool { return s.compare(s.s[i], s.s[j]) }
|
||||
func (s sliceFn[T]) Swap(i, j int) { s.s[i], s.s[j] = s.s[j], s.s[i] }
|
||||
```</p>
|
||||
<p>Conversely, when is it recommended <strong>not</strong> to use generics?</p>
|
||||
<ul>
|
||||
<li>When just calling a method of the type argument. For example, consider a function that receives an <code>io.Writer</code> and call the <code>Write</code> method:</li>
|
||||
</ul>
|
||||
<p><code>cgo
|
||||
func foo[T io.Writer](w T) {
|
||||
b := getBytes()
|
||||
_, _ = w.Write(b)
|
||||
}</code></p>
|
||||
<ul>
|
||||
<li>When it makes our code more complex. Generics are never mandatory, and as Go developers, we have been able to live without them for more than a decade. If writing generic functions or structures we figure out that it doesn’t make our code clearer, we should probably reconsider our decision for this particular use case.</li>
|
||||
</ul>
|
||||
<h2 id="conclusion">Conclusion</h2>
|
||||
<p>Though generics can be very helpful in particular conditions, we should be cautious about when to use them and not use them.</p>
|
||||
<p>In general, when we want to answer when not to use generics, we can find similarities with when not to use interfaces. Indeed, generics introduce a form of abstraction, and we have to remember that unnecessary abstractions introduce complexity.</p>
|
||||
<p>Let’s not pollute our code with needless abstractions, and let’s focus on solving concrete problems for now. It means that we shouldn’t use type parameters prematurely. Let’s wait until we are about to write boilerplate code to consider using generics.</p>
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
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</article>
|
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|
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|
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|
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<script id="__config" type="application/json">{"base": "..", "features": [], "search": "../assets/javascripts/workers/search.dfff1995.min.js", "translations": {"clipboard.copied": "Copied to clipboard", "clipboard.copy": "Copy to clipboard", "search.result.more.one": "1 more on this page", "search.result.more.other": "# more on this page", "search.result.none": "No matching documents", "search.result.one": "1 matching document", "search.result.other": "# matching documents", "search.result.placeholder": "Type to start searching", "search.result.term.missing": "Missing", "select.version": "Select version"}}</script>
|
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|
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|
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|
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|
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|
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|
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|
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|
|
@ -1,808 +0,0 @@
|
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|
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|
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<script>__md_scope=new URL("..",location),__md_hash=e=>[...e].reduce((e,_)=>(e<<5)-e+_.charCodeAt(0),0),__md_get=(e,_=localStorage,t=__md_scope)=>JSON.parse(_.getItem(t.pathname+"."+e)),__md_set=(e,_,t=localStorage,a=__md_scope)=>{try{t.setItem(a.pathname+"."+e,JSON.stringify(_))}catch(e){}}</script>
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<body dir="ltr" data-md-color-scheme="default" data-md-color-primary="green" data-md-color-accent="indigo">
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<script>var palette=__md_get("__palette");if(palette&&"object"==typeof palette.color)for(var key of Object.keys(palette.color))document.body.setAttribute("data-md-color-"+key,palette.color[key])</script>
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|
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|
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<div data-md-component="skip">
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Skip to content
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<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 24 24"><path d="M3 6h18v2H3V6m0 5h18v2H3v-2m0 5h18v2H3v-2Z"/></svg>
|
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</label>
|
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<div class="md-header__title" data-md-component="header-title">
|
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<div class="md-header__ellipsis">
|
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<div class="md-header__topic">
|
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<span class="md-ellipsis">
|
||||
100 Go Mistakes
|
||||
</span>
|
||||
</div>
|
||||
<div class="md-header__topic" data-md-component="header-topic">
|
||||
<span class="md-ellipsis">
|
||||
|
||||
Go: Simple to learn but hard to master
|
||||
|
||||
</span>
|
||||
</div>
|
||||
</div>
|
||||
</div>
|
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|
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<form class="md-header__option" data-md-component="palette">
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<input class="md-option" data-md-color-media="" data-md-color-scheme="default" data-md-color-primary="green" data-md-color-accent="indigo" aria-label="Switch to dark mode" type="radio" name="__palette" id="__palette_1">
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<label class="md-header__button md-icon" title="Switch to dark mode" for="__palette_2" hidden>
|
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<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 24 24"><path d="M12 8a4 4 0 0 0-4 4 4 4 0 0 0 4 4 4 4 0 0 0 4-4 4 4 0 0 0-4-4m0 10a6 6 0 0 1-6-6 6 6 0 0 1 6-6 6 6 0 0 1 6 6 6 6 0 0 1-6 6m8-9.31V4h-4.69L12 .69 8.69 4H4v4.69L.69 12 4 15.31V20h4.69L12 23.31 15.31 20H20v-4.69L23.31 12 20 8.69Z"/></svg>
|
||||
</label>
|
||||
|
||||
|
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|
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|
||||
|
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<input class="md-option" data-md-color-media="" data-md-color-scheme="slate" data-md-color-primary="blue-grey" data-md-color-accent="indigo" aria-label="Switch to light mode" type="radio" name="__palette" id="__palette_2">
|
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<label class="md-header__button md-icon" title="Switch to light mode" for="__palette_1" hidden>
|
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<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 24 24"><path d="M12 18c-.89 0-1.74-.2-2.5-.55C11.56 16.5 13 14.42 13 12c0-2.42-1.44-4.5-3.5-5.45C10.26 6.2 11.11 6 12 6a6 6 0 0 1 6 6 6 6 0 0 1-6 6m8-9.31V4h-4.69L12 .69 8.69 4H4v4.69L.69 12 4 15.31V20h4.69L12 23.31 15.31 20H20v-4.69L23.31 12 20 8.69Z"/></svg>
|
||||
</label>
|
||||
|
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|
||||
</form>
|
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|
||||
|
||||
|
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<div class="md-header__option">
|
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<div class="md-select">
|
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<button class="md-header__button md-icon" aria-label="Select language">
|
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<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 24 24"><path d="m12.87 15.07-2.54-2.51.03-.03A17.52 17.52 0 0 0 14.07 6H17V4h-7V2H8v2H1v2h11.17C11.5 7.92 10.44 9.75 9 11.35 8.07 10.32 7.3 9.19 6.69 8h-2c.73 1.63 1.73 3.17 2.98 4.56l-5.09 5.02L4 19l5-5 3.11 3.11.76-2.04M18.5 10h-2L12 22h2l1.12-3h4.75L21 22h2l-4.5-12m-2.62 7 1.62-4.33L19.12 17h-3.24Z"/></svg>
|
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</button>
|
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<div class="md-select__inner">
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<ul class="md-select__list">
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<a href="/" hreflang="en" class="md-select__link">
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English
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<li class="md-select__item">
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<a href="/chinese/" hreflang="zh" class="md-select__link">
|
||||
Chinese (Simplified)
|
||||
</a>
|
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</li>
|
||||
|
||||
</ul>
|
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</div>
|
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</div>
|
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|
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<label class="md-header__button md-icon" for="__search">
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<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 24 24"><path d="M9.5 3A6.5 6.5 0 0 1 16 9.5c0 1.61-.59 3.09-1.56 4.23l.27.27h.79l5 5-1.5 1.5-5-5v-.79l-.27-.27A6.516 6.516 0 0 1 9.5 16 6.5 6.5 0 0 1 3 9.5 6.5 6.5 0 0 1 9.5 3m0 2C7 5 5 7 5 9.5S7 14 9.5 14 14 12 14 9.5 12 5 9.5 5Z"/></svg>
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</label>
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<div class="md-search" data-md-component="search" role="dialog">
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<label class="md-search__overlay" for="__search"></label>
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<div class="md-search__inner" role="search">
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<form class="md-search__form" name="search">
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<input type="text" class="md-search__input" name="query" aria-label="Search" placeholder="Search" autocapitalize="off" autocorrect="off" autocomplete="off" spellcheck="false" data-md-component="search-query" required>
|
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<label class="md-search__icon md-icon" for="__search">
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<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 24 24"><path d="M9.5 3A6.5 6.5 0 0 1 16 9.5c0 1.61-.59 3.09-1.56 4.23l.27.27h.79l5 5-1.5 1.5-5-5v-.79l-.27-.27A6.516 6.516 0 0 1 9.5 16 6.5 6.5 0 0 1 3 9.5 6.5 6.5 0 0 1 9.5 3m0 2C7 5 5 7 5 9.5S7 14 9.5 14 14 12 14 9.5 12 5 9.5 5Z"/></svg>
|
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|
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<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 24 24"><path d="M20 11v2H8l5.5 5.5-1.42 1.42L4.16 12l7.92-7.92L13.5 5.5 8 11h12Z"/></svg>
|
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</label>
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<nav class="md-search__options" aria-label="Search">
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<button type="reset" class="md-search__icon md-icon" title="Clear" aria-label="Clear" tabindex="-1">
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<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 24 24"><path d="M19 6.41 17.59 5 12 10.59 6.41 5 5 6.41 10.59 12 5 17.59 6.41 19 12 13.41 17.59 19 19 17.59 13.41 12 19 6.41Z"/></svg>
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|
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</nav>
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</form>
|
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<div class="md-search__output">
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<div class="md-search__scrollwrap" data-md-scrollfix>
|
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<div class="md-search-result" data-md-component="search-result">
|
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<div class="md-search-result__meta">
|
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Initializing search
|
||||
</div>
|
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<ol class="md-search-result__list" role="presentation"></ol>
|
||||
</div>
|
||||
</div>
|
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|
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</div>
|
||||
</div>
|
||||
|
||||
|
||||
<div class="md-header__source">
|
||||
<a href="https://github.com/teivah/100-go-mistakes" title="Go to repository" class="md-source" data-md-component="source">
|
||||
<div class="md-source__icon md-icon">
|
||||
|
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<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 448 512"><!--! Font Awesome Free 6.4.2 by @fontawesome - https://fontawesome.com License - https://fontawesome.com/license/free (Icons: CC BY 4.0, Fonts: SIL OFL 1.1, Code: MIT License) Copyright 2023 Fonticons, Inc.--><path d="M439.55 236.05 244 40.45a28.87 28.87 0 0 0-40.81 0l-40.66 40.63 51.52 51.52c27.06-9.14 52.68 16.77 43.39 43.68l49.66 49.66c34.23-11.8 61.18 31 35.47 56.69-26.49 26.49-70.21-2.87-56-37.34L240.22 199v121.85c25.3 12.54 22.26 41.85 9.08 55a34.34 34.34 0 0 1-48.55 0c-17.57-17.6-11.07-46.91 11.25-56v-123c-20.8-8.51-24.6-30.74-18.64-45L142.57 101 8.45 235.14a28.86 28.86 0 0 0 0 40.81l195.61 195.6a28.86 28.86 0 0 0 40.8 0l194.69-194.69a28.86 28.86 0 0 0 0-40.81z"/></svg>
|
||||
</div>
|
||||
<div class="md-source__repository">
|
||||
GitHub
|
||||
</div>
|
||||
</a>
|
||||
</div>
|
||||
|
||||
</nav>
|
||||
|
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</header>
|
||||
|
||||
<div class="md-container" data-md-component="container">
|
||||
|
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|
||||
|
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|
||||
|
||||
|
||||
<main class="md-main" data-md-component="main">
|
||||
<div class="md-main__inner md-grid">
|
||||
|
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|
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|
||||
<div class="md-sidebar md-sidebar--primary" data-md-component="sidebar" data-md-type="navigation" >
|
||||
<div class="md-sidebar__scrollwrap">
|
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<div class="md-sidebar__inner">
|
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|
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|
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|
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|
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<nav class="md-nav md-nav--primary" aria-label="Navigation" data-md-level="0">
|
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<label class="md-nav__title" for="__drawer">
|
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|
||||
|
||||
<img src="../Go-Logo_Fuchsia.svg" alt="logo">
|
||||
|
||||
</a>
|
||||
100 Go Mistakes
|
||||
</label>
|
||||
|
||||
<div class="md-nav__source">
|
||||
<a href="https://github.com/teivah/100-go-mistakes" title="Go to repository" class="md-source" data-md-component="source">
|
||||
<div class="md-source__icon md-icon">
|
||||
|
||||
<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 448 512"><!--! Font Awesome Free 6.4.2 by @fontawesome - https://fontawesome.com License - https://fontawesome.com/license/free (Icons: CC BY 4.0, Fonts: SIL OFL 1.1, Code: MIT License) Copyright 2023 Fonticons, Inc.--><path d="M439.55 236.05 244 40.45a28.87 28.87 0 0 0-40.81 0l-40.66 40.63 51.52 51.52c27.06-9.14 52.68 16.77 43.39 43.68l49.66 49.66c34.23-11.8 61.18 31 35.47 56.69-26.49 26.49-70.21-2.87-56-37.34L240.22 199v121.85c25.3 12.54 22.26 41.85 9.08 55a34.34 34.34 0 0 1-48.55 0c-17.57-17.6-11.07-46.91 11.25-56v-123c-20.8-8.51-24.6-30.74-18.64-45L142.57 101 8.45 235.14a28.86 28.86 0 0 0 0 40.81l195.61 195.6a28.86 28.86 0 0 0 40.8 0l194.69-194.69a28.86 28.86 0 0 0 0-40.81z"/></svg>
|
||||
</div>
|
||||
<div class="md-source__repository">
|
||||
GitHub
|
||||
</div>
|
||||
</a>
|
||||
</div>
|
||||
|
||||
<ul class="md-nav__list" data-md-scrollfix>
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
<li class="md-nav__item">
|
||||
<a href=".." class="md-nav__link">
|
||||
|
||||
|
||||
<span class="md-ellipsis">
|
||||
📖 Book Presentation
|
||||
</span>
|
||||
|
||||
|
||||
</a>
|
||||
</li>
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
<li class="md-nav__item">
|
||||
<a href="../9-generics/" class="md-nav__link">
|
||||
|
||||
|
||||
<span class="md-ellipsis">
|
||||
Being confused about when to use generics (#9)
|
||||
</span>
|
||||
|
||||
|
||||
</a>
|
||||
</li>
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
<li class="md-nav__item md-nav__item--active">
|
||||
|
||||
<input class="md-nav__toggle md-toggle" type="checkbox" id="__toc">
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
<label class="md-nav__link md-nav__link--active" for="__toc">
|
||||
|
||||
|
||||
<span class="md-ellipsis">
|
||||
Go: Simple to learn but hard to master
|
||||
</span>
|
||||
|
||||
|
||||
<span class="md-nav__icon md-icon"></span>
|
||||
</label>
|
||||
|
||||
<a href="./" class="md-nav__link md-nav__link--active">
|
||||
|
||||
|
||||
<span class="md-ellipsis">
|
||||
Go: Simple to learn but hard to master
|
||||
</span>
|
||||
|
||||
|
||||
</a>
|
||||
|
||||
|
||||
|
||||
<nav class="md-nav md-nav--secondary" aria-label="Table of contents">
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
<label class="md-nav__title" for="__toc">
|
||||
<span class="md-nav__icon md-icon"></span>
|
||||
Table of contents
|
||||
</label>
|
||||
<ul class="md-nav__list" data-md-component="toc" data-md-scrollfix>
|
||||
|
||||
<li class="md-nav__item">
|
||||
<a href="#go-outline" class="md-nav__link">
|
||||
Go outline
|
||||
</a>
|
||||
|
||||
</li>
|
||||
|
||||
<li class="md-nav__item">
|
||||
<a href="#simple-doesnt-mean-easy" class="md-nav__link">
|
||||
Simple doesn’t mean easy
|
||||
</a>
|
||||
|
||||
</li>
|
||||
|
||||
<li class="md-nav__item">
|
||||
<a href="#100-go-mistakes" class="md-nav__link">
|
||||
100 Go mistakes
|
||||
</a>
|
||||
|
||||
<nav class="md-nav" aria-label="100 Go mistakes">
|
||||
<ul class="md-nav__list">
|
||||
|
||||
<li class="md-nav__item">
|
||||
<a href="#bugs" class="md-nav__link">
|
||||
Bugs
|
||||
</a>
|
||||
|
||||
</li>
|
||||
|
||||
<li class="md-nav__item">
|
||||
<a href="#needless-complexity" class="md-nav__link">
|
||||
Needless complexity
|
||||
</a>
|
||||
|
||||
</li>
|
||||
|
||||
<li class="md-nav__item">
|
||||
<a href="#weaker-readability" class="md-nav__link">
|
||||
Weaker readability
|
||||
</a>
|
||||
|
||||
</li>
|
||||
|
||||
<li class="md-nav__item">
|
||||
<a href="#suboptimal-or-unidiomatic-organization" class="md-nav__link">
|
||||
Suboptimal or unidiomatic organization
|
||||
</a>
|
||||
|
||||
</li>
|
||||
|
||||
<li class="md-nav__item">
|
||||
<a href="#lack-of-api-convenience" class="md-nav__link">
|
||||
Lack of API convenience
|
||||
</a>
|
||||
|
||||
</li>
|
||||
|
||||
<li class="md-nav__item">
|
||||
<a href="#under-optimized-code" class="md-nav__link">
|
||||
Under-optimized code
|
||||
</a>
|
||||
|
||||
</li>
|
||||
|
||||
<li class="md-nav__item">
|
||||
<a href="#lack-of-productivity" class="md-nav__link">
|
||||
Lack of productivity
|
||||
</a>
|
||||
|
||||
</li>
|
||||
|
||||
</ul>
|
||||
</nav>
|
||||
|
||||
</li>
|
||||
|
||||
<li class="md-nav__item">
|
||||
<a href="#summary" class="md-nav__link">
|
||||
Summary
|
||||
</a>
|
||||
|
||||
</li>
|
||||
|
||||
</ul>
|
||||
|
||||
</nav>
|
||||
|
||||
</li>
|
||||
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||||
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||||
|
||||
|
||||
<li class="md-nav__item">
|
||||
<a href="../jobs/" class="md-nav__link">
|
||||
|
||||
|
||||
<span class="md-ellipsis">
|
||||
❤️ Go Jobs
|
||||
</span>
|
||||
|
||||
|
||||
</a>
|
||||
</li>
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
<li class="md-nav__item">
|
||||
<a href="../mistakes/" class="md-nav__link">
|
||||
|
||||
|
||||
<span class="md-ellipsis">
|
||||
💡 Go Mistakes
|
||||
</span>
|
||||
|
||||
|
||||
</a>
|
||||
</li>
|
||||
|
||||
|
||||
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||||
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||||
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|
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|
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<label class="md-nav__link" for="__nav_6" id="__nav_6_label" tabindex="0">
|
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|
||||
|
||||
<span class="md-ellipsis">
|
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Chinese
|
||||
</span>
|
||||
|
||||
|
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<span class="md-nav__icon md-icon"></span>
|
||||
</label>
|
||||
|
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<nav class="md-nav" data-md-level="1" aria-labelledby="__nav_6_label" aria-expanded="false">
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<label class="md-nav__title" for="__nav_6">
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<span class="md-nav__icon md-icon"></span>
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Chinese
|
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</label>
|
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<ul class="md-nav__list" data-md-scrollfix>
|
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|
||||
|
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|
||||
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|
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|
||||
<a href="../chinese/presentation/" class="md-nav__link">
|
||||
|
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|
||||
<span class="md-ellipsis">
|
||||
Presentation
|
||||
</span>
|
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|
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|
||||
</a>
|
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</li>
|
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||||
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||||
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|
||||
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||||
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||||
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|
||||
</div>
|
||||
</div>
|
||||
</div>
|
||||
|
||||
|
||||
|
||||
<div class="md-sidebar md-sidebar--secondary" data-md-component="sidebar" data-md-type="toc" >
|
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<div class="md-sidebar__scrollwrap">
|
||||
<div class="md-sidebar__inner">
|
||||
|
||||
|
||||
<nav class="md-nav md-nav--secondary" aria-label="Table of contents">
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||||
<label class="md-nav__title" for="__toc">
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||||
<span class="md-nav__icon md-icon"></span>
|
||||
Table of contents
|
||||
</label>
|
||||
<ul class="md-nav__list" data-md-component="toc" data-md-scrollfix>
|
||||
|
||||
<li class="md-nav__item">
|
||||
<a href="#go-outline" class="md-nav__link">
|
||||
Go outline
|
||||
</a>
|
||||
|
||||
</li>
|
||||
|
||||
<li class="md-nav__item">
|
||||
<a href="#simple-doesnt-mean-easy" class="md-nav__link">
|
||||
Simple doesn’t mean easy
|
||||
</a>
|
||||
|
||||
</li>
|
||||
|
||||
<li class="md-nav__item">
|
||||
<a href="#100-go-mistakes" class="md-nav__link">
|
||||
100 Go mistakes
|
||||
</a>
|
||||
|
||||
<nav class="md-nav" aria-label="100 Go mistakes">
|
||||
<ul class="md-nav__list">
|
||||
|
||||
<li class="md-nav__item">
|
||||
<a href="#bugs" class="md-nav__link">
|
||||
Bugs
|
||||
</a>
|
||||
|
||||
</li>
|
||||
|
||||
<li class="md-nav__item">
|
||||
<a href="#needless-complexity" class="md-nav__link">
|
||||
Needless complexity
|
||||
</a>
|
||||
|
||||
</li>
|
||||
|
||||
<li class="md-nav__item">
|
||||
<a href="#weaker-readability" class="md-nav__link">
|
||||
Weaker readability
|
||||
</a>
|
||||
|
||||
</li>
|
||||
|
||||
<li class="md-nav__item">
|
||||
<a href="#suboptimal-or-unidiomatic-organization" class="md-nav__link">
|
||||
Suboptimal or unidiomatic organization
|
||||
</a>
|
||||
|
||||
</li>
|
||||
|
||||
<li class="md-nav__item">
|
||||
<a href="#lack-of-api-convenience" class="md-nav__link">
|
||||
Lack of API convenience
|
||||
</a>
|
||||
|
||||
</li>
|
||||
|
||||
<li class="md-nav__item">
|
||||
<a href="#under-optimized-code" class="md-nav__link">
|
||||
Under-optimized code
|
||||
</a>
|
||||
|
||||
</li>
|
||||
|
||||
<li class="md-nav__item">
|
||||
<a href="#lack-of-productivity" class="md-nav__link">
|
||||
Lack of productivity
|
||||
</a>
|
||||
|
||||
</li>
|
||||
|
||||
</ul>
|
||||
</nav>
|
||||
|
||||
</li>
|
||||
|
||||
<li class="md-nav__item">
|
||||
<a href="#summary" class="md-nav__link">
|
||||
Summary
|
||||
</a>
|
||||
|
||||
</li>
|
||||
|
||||
</ul>
|
||||
|
||||
</nav>
|
||||
</div>
|
||||
</div>
|
||||
</div>
|
||||
|
||||
|
||||
|
||||
<div class="md-content" data-md-component="content">
|
||||
<article class="md-content__inner md-typeset">
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
<h1 id="go-simple-to-learn-but-hard-to-master">Go: Simple to learn but hard to master</h1>
|
||||
<p>This chapter covers
|
||||
* What makes Go an efficient, scalable, and productive language
|
||||
* Exploring why Go is simple to learn but hard to master
|
||||
* Presenting the common types of mistakes made by developers</p>
|
||||
<p>Making mistakes is part of everyone’s life. As Albert Einstein once said,</p>
|
||||
<blockquote>
|
||||
<p>A person who never made a mistake never tried anything new.</p>
|
||||
</blockquote>
|
||||
<p>What matters in the end isn’t the number of mistakes we make, but our capacity to learn from them. This assertion also applies to programming. The seniority we acquire in a language isn’t a magical process; it involves making many mistakes and learning from them. The purpose of this book is centered around this idea. It will help you, the reader, become a more proficient Go developer by looking at and learning from 100 common mistakes people make in many areas of the language.</p>
|
||||
<p>This chapter presents a quick refresher as to why Go has become mainstream over the years. We’ll discuss why, despite Go being considered simple to learn, mastering its nuances can be challenging. Finally, we’ll introduce the concepts this book covers.</p>
|
||||
<h2 id="go-outline">Go outline</h2>
|
||||
<p>If you are reading this book, it’s likely that you’re already sold on Go. Therefore, this section provides a brief reminder about what makes Go such a powerful language.</p>
|
||||
<p>Software engineering has evolved considerably during the past decades. Most modern systems are no longer written by a single person but by teams consisting of multiple programmers—sometimes even hundreds, if not thousands. Nowadays, code must be readable, expressive, and maintainable to guarantee a system’s durability over the years. Meanwhile, in our fast-moving world, maximizing agility and reducing the time to market is critical for most organizations. Programming should also follow this trend, and companies strive to ensure that software engineers are as productive as possible when reading, writing, and maintaining code.</p>
|
||||
<p>In response to these challenges, Google created the Go programming language in 2007. Since then, many organizations have adopted the language to support various use cases: APIs, automation, databases, CLIs (command-line interfaces), and so on. Many today consider Go the language of the cloud.</p>
|
||||
<p>Feature-wise, Go has no type inheritance, no exceptions, no macros, no partial functions, no support for lazy variable evaluation or immutability, no operator overloading, no pattern matching, and on and on. Why are these features missing from the language? The official <a href="https://go.dev/doc/faq">Go FAQ</a> gives us some insight:</p>
|
||||
<blockquote>
|
||||
<p>Why does Go not have feature X? Your favorite feature may be missing because it doesn’t fit, because it affects compilation speed or clarity of design, or because it would make the fundamental system model too difficult.</p>
|
||||
</blockquote>
|
||||
<p>Judging the quality of a programming language via its number of features is probably not an accurate metric. At least, it’s not an objective of Go. Instead, Go utilizes a few essential characteristics when adopting a language at scale for an organization. These include the following:</p>
|
||||
<ul>
|
||||
<li><em>Stability</em>—Even though Go receives frequent updates (including improvements and security patches), it remains a stable language. Some may even consider this one of the best features of the language.</li>
|
||||
<li><em>Expressivity</em>—We can define expressivity in a programming language by how naturally and intuitively we can write and read code. A reduced number of keywords and limited ways to solve common problems make Go an expressive language for large codebases.</li>
|
||||
<li><em>Compilation</em>—As developers, what can be more exasperating than having to wait for a build to test our application? Targeting fast compilation times has always been a conscious goal for the language designers. This, in turn, enables productivity.</li>
|
||||
<li><em>Safety</em>—Go is a strong, statically typed language. Hence, it has strict compiletime rules, which ensure the code is type-safe in most cases.</li>
|
||||
</ul>
|
||||
<p>Go was built from the ground up with solid features such as outstanding concurrency primitives with goroutines and channels. There’s not a strong need to rely on external libraries to build efficient concurrent applications. Observing how important concurrency is these days also demonstrates why Go is such a suitable language for the present and probably for the foreseeable future.</p>
|
||||
<p>Some also consider Go a simple language. And, in a sense, this isn’t necessarily wrong. For example, a newcomer can learn the language’s main features in less than a day. So why read a book centered on the concept of mistakes if Go is simple?</p>
|
||||
<h2 id="simple-doesnt-mean-easy">Simple doesn’t mean easy</h2>
|
||||
<p>There is a subtle difference between simple and easy. <em>Simple</em>, applied to a technology, means not complicated to learn or understand. However, <em>easy</em> means that we can achieve anything without much effort. Go is simple to learn but not necessarily easy to master.</p>
|
||||
<p>Let’s take concurrency, for example. In 2019, a study focusing on concurrency bugs was published: <a href="https://songlh.github.io/paper/go-study.pdf">Understanding Real-World Concurrency Bugs in Go</a>. This study was the first systematic analysis of concurrency bugs. It focused on multiple popular Go repositories such as Docker, gRPC, and Kubernetes. One of the most important takeaways from this study is that most of the blocking bugs are caused by inaccurate use of the message-passing paradigm via channels, despite the belief that message passing is easier to handle and less error-prone than sharing memory.</p>
|
||||
<p>What should be an appropriate reaction to such a takeaway? Should we consider that the language designers were wrong about message passing? Should we reconsider how we deal with concurrency in our project? Of course not.</p>
|
||||
<p>It’s not a question of confronting message passing versus sharing memory and determining the winner. However, it’s up to us as Go developers to thoroughly understand how to use concurrency, its implications on modern processors, when to favor one approach over the other, and how to avoid common traps. This example highlights that although a concept such as channels and goroutines can be simple to learn, it isn’t an easy topic in practice.</p>
|
||||
<p>This leitmotif—simple doesn’t mean easy—can be generalized to many aspects of Go, not only concurrency. Hence, to be proficient Go developers, we must have a thorough understanding of many aspects of the language, which requires time, effort, and mistakes.</p>
|
||||
<p>This book aims to help accelerate our journey toward proficiency by delving into 100 Go mistakes.</p>
|
||||
<h2 id="100-go-mistakes">100 Go mistakes</h2>
|
||||
<p>Why should we read a book about common Go mistakes? Why not deepen our knowledge with an ordinary book that would dig into different topics?</p>
|
||||
<p>In a 2011 article, neuroscientists proved that the best time for brain growth is when we’re facing mistakes. Haven’t we all experienced the process of learning from a mistake and recalling that occasion after months or even years, when some context related to it? As presented in another article, by Janet Metcalfe, this happens because mistakes have a facilitative effect. The main idea is that we can remember not only the error but also the context surrounding the mistake. This is one of the reasons why learning from mistakes is so efficient.</p>
|
||||
<p>To strengthen this facilitative effect, this book accompanies each mistake as much as possible with real-world examples. This book isn’t only about theory; it also helps us get better at avoiding mistakes and making more well-informed, conscious decisions because we now understand the rationale behind them.</p>
|
||||
<blockquote>
|
||||
<p>Tell me and I forget. Teach me and I remember. Involve me and I learn.</p>
|
||||
</blockquote>
|
||||
<p><em>- Unknown</em></p>
|
||||
<p>This book presents seven main categories of mistakes. Overall, the mistakes can be classified as
|
||||
* Bugs
|
||||
* Needless complexity
|
||||
* Weaker readability
|
||||
* Suboptimal or unidiomatic organization
|
||||
* Lack of API convenience
|
||||
* Under-optimized code
|
||||
* Lack of productivity</p>
|
||||
<p>We introduce each mistake category next.</p>
|
||||
<h3 id="bugs">Bugs</h3>
|
||||
<p>The first type of mistake and probably the most obvious is software bugs. In 2020, a study conducted by Synopsys estimated the cost of software bugs in the U.S. alone to be over $2 trillion.</p>
|
||||
<p>Furthermore, bugs can also lead to tragic impacts. We can, for example, mention cases such as Therac-25, a radiation therapy machine produced by Atomic Energy of Canada Limited (AECL). Because of a race condition, the machine gave its patients radiation doses that were hundreds of times greater than expected, leading to the death of three patients. Hence, software bugs aren’t only about money. As developers, we should remember how impactful our jobs are.</p>
|
||||
<p>This book covers plenty of cases that could lead to various software bugs, including data races, leaks, logic errors, and other defects. Although accurate tests should be a way to discover such bugs as early as possible, we may sometimes miss cases because of different factors such as time constraints or complexity. Therefore, as a Go developer, it’s essential to make sure we avoid common bugs.</p>
|
||||
<h3 id="needless-complexity">Needless complexity</h3>
|
||||
<p>The next category of mistakes is related to unnecessary complexity. A significant part of software complexity comes from the fact that, as developers, we strive to think about imaginary futures. Instead of solving concrete problems right now, it can be tempting to build evolutionary software that could tackle whatever future use case arises. However, this leads to more drawbacks than benefits in most cases because it can make a codebase more complex to understand and reason about.</p>
|
||||
<p>Getting back to Go, we can think of plenty of use cases where developers might be tempted to design abstractions for future needs, such as interfaces or generics. This book discusses topics where we should remain careful not to harm a codebase with needless complexity.</p>
|
||||
<h3 id="weaker-readability">Weaker readability</h3>
|
||||
<p>Another kind of mistake is to weaken readability. As Robert C. Martin wrote in his book <em>Clean Code: A Handbook of Agile Software Craftsmanship</em>, the ratio of time spent reading versus writing is well over 10 to 1. Most of us started to program on solo projects where readability wasn’t that important. However, today’s software engineering is programming with a time dimension: making sure we can still work with and maintain an application months, years, or perhaps even decades later.</p>
|
||||
<p>When programming in Go, we can make many mistakes that can harm readability. These mistakes may include nested code, data type representations, or not using named result parameters in some cases. Throughout this book, we will learn how to write readable code and care for future readers (including our future selves).</p>
|
||||
<h3 id="suboptimal-or-unidiomatic-organization">Suboptimal or unidiomatic organization</h3>
|
||||
<p>Be it while working on a new project or because we acquire inaccurate reflexes, another type of mistake is organizing our code and a project suboptimally and unidiomatically. Such issues can make a project harder to reason about and maintain. This book covers some of these common mistakes in Go. For example, we’ll look at how to structure a project and deal with utility packages or init functions. All in all, looking at these mistakes should help us organize our code and projects more efficiently and idiomatically.</p>
|
||||
<h3 id="lack-of-api-convenience">Lack of API convenience</h3>
|
||||
<p>Making common mistakes that weaken how convenient an API is for our clients is another type of mistake. If an API isn’t user-friendly, it will be less expressive and, hence, harder to understand and more error-prone.</p>
|
||||
<p>We can think about many situations such as overusing any types, using the wrong creational pattern to deal with options, or blindly applying standard practices from object-oriented programming that affect the usability of our APIs. This book covers common mistakes that prevent us from exposing convenient APIs for our users.</p>
|
||||
<h3 id="under-optimized-code">Under-optimized code</h3>
|
||||
<p>Under-optimized code is another type of mistake made by developers. It can happen for various reasons, such as not understanding language features or even a lack of fundamental knowledge. Performance is one of the most obvious impacts of this mistake, but not the only one.</p>
|
||||
<p>We can think about optimizing code for other goals, such as accuracy. For example, this book provides some common techniques to ensure that floating-point operations are accurate. Meanwhile, we will cover plenty of cases that can negatively impact performance code because of poorly parallelized executions, not knowing how to reduce allocations, or the impacts of data alignment, for example. We will tackle optimization via different prisms.</p>
|
||||
<h3 id="lack-of-productivity">Lack of productivity</h3>
|
||||
<p>In most cases, what’s the best language we can choose when working on a new project? The one we’re the most productive with. Being comfortable with how a language works and exploiting it to get the best out of it is crucial to reach proficiency.</p>
|
||||
<p>In this book, we will cover many cases and concrete examples that will help us to be more productive while working in Go. For instance, we’ll look at writing efficient tests to ensure that our code works, relying on the standard library to be more effective, and getting the best out of the profiling tools and linters. Now, it’s time to delve into those 100 common Go mistakes.</p>
|
||||
<h2 id="summary">Summary</h2>
|
||||
<ul>
|
||||
<li>Go is a modern programming language that enables developer productivity, which is crucial for most companies today.</li>
|
||||
<li>Go is simple to learn but not easy to master. This is why we need to deepen our knowledge to make the most effective use of the language.</li>
|
||||
<li>Learning via mistakes and concrete examples is a powerful way to be proficient in a language. This book will accelerate our path to proficiency by exploring 100 common mistakes.</li>
|
||||
</ul>
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
</article>
|
||||
</div>
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|
||||
</div>
|
||||
|
||||
</div>
|
||||
</div>
|
||||
</footer>
|
||||
|
||||
</div>
|
||||
<div class="md-dialog" data-md-component="dialog">
|
||||
<div class="md-dialog__inner md-typeset"></div>
|
||||
</div>
|
||||
|
||||
<script id="__config" type="application/json">{"base": "..", "features": [], "search": "../assets/javascripts/workers/search.dfff1995.min.js", "translations": {"clipboard.copied": "Copied to clipboard", "clipboard.copy": "Copy to clipboard", "search.result.more.one": "1 more on this page", "search.result.more.other": "# more on this page", "search.result.none": "No matching documents", "search.result.one": "1 matching document", "search.result.other": "# matching documents", "search.result.placeholder": "Type to start searching", "search.result.term.missing": "Missing", "select.version": "Select version"}}</script>
|
||||
|
||||
|
||||
<script src="../assets/javascripts/bundle.dff1b7c8.min.js"></script>
|
||||
|
||||
|
||||
</body>
|
||||
</html>
|
||||
|
|
@ -283,44 +283,6 @@
|
|||
|
||||
|
||||
|
||||
<li class="md-nav__item">
|
||||
<a href="../../9-generics/" class="md-nav__link">
|
||||
|
||||
|
||||
<span class="md-ellipsis">
|
||||
Being confused about when to use generics (#9)
|
||||
</span>
|
||||
|
||||
|
||||
</a>
|
||||
</li>
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
<li class="md-nav__item">
|
||||
<a href="../../chapter-1/" class="md-nav__link">
|
||||
|
||||
|
||||
<span class="md-ellipsis">
|
||||
Go: Simple to learn but hard to master
|
||||
</span>
|
||||
|
||||
|
||||
</a>
|
||||
</li>
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
<li class="md-nav__item">
|
||||
<a href="../../jobs/" class="md-nav__link">
|
||||
|
||||
|
|
@ -370,9 +332,9 @@
|
|||
|
||||
|
||||
|
||||
<input class="md-nav__toggle md-toggle " type="checkbox" id="__nav_6" checked>
|
||||
<input class="md-nav__toggle md-toggle " type="checkbox" id="__nav_4" checked>
|
||||
|
||||
<label class="md-nav__link" for="__nav_6" id="__nav_6_label" tabindex="0">
|
||||
<label class="md-nav__link" for="__nav_4" id="__nav_4_label" tabindex="0">
|
||||
|
||||
|
||||
<span class="md-ellipsis">
|
||||
|
|
@ -383,8 +345,8 @@
|
|||
<span class="md-nav__icon md-icon"></span>
|
||||
</label>
|
||||
|
||||
<nav class="md-nav" data-md-level="1" aria-labelledby="__nav_6_label" aria-expanded="true">
|
||||
<label class="md-nav__title" for="__nav_6">
|
||||
<nav class="md-nav" data-md-level="1" aria-labelledby="__nav_4_label" aria-expanded="true">
|
||||
<label class="md-nav__title" for="__nav_4">
|
||||
<span class="md-nav__icon md-icon"></span>
|
||||
Chinese
|
||||
</label>
|
||||
|
|
|
|||
|
|
@ -10,7 +10,7 @@
|
|||
|
||||
|
||||
|
||||
<link rel="next" href="9-generics/">
|
||||
<link rel="next" href="jobs/">
|
||||
|
||||
|
||||
<link rel="icon" href="Go-Logo_Fuchsia.svg">
|
||||
|
|
@ -403,44 +403,6 @@
|
|||
|
||||
|
||||
|
||||
<li class="md-nav__item">
|
||||
<a href="9-generics/" class="md-nav__link">
|
||||
|
||||
|
||||
<span class="md-ellipsis">
|
||||
Being confused about when to use generics (#9)
|
||||
</span>
|
||||
|
||||
|
||||
</a>
|
||||
</li>
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
<li class="md-nav__item">
|
||||
<a href="chapter-1/" class="md-nav__link">
|
||||
|
||||
|
||||
<span class="md-ellipsis">
|
||||
Go: Simple to learn but hard to master
|
||||
</span>
|
||||
|
||||
|
||||
</a>
|
||||
</li>
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
<li class="md-nav__item">
|
||||
<a href="jobs/" class="md-nav__link">
|
||||
|
||||
|
|
@ -488,9 +450,9 @@
|
|||
|
||||
|
||||
|
||||
<input class="md-nav__toggle md-toggle " type="checkbox" id="__nav_6" >
|
||||
<input class="md-nav__toggle md-toggle " type="checkbox" id="__nav_4" >
|
||||
|
||||
<label class="md-nav__link" for="__nav_6" id="__nav_6_label" tabindex="0">
|
||||
<label class="md-nav__link" for="__nav_4" id="__nav_4_label" tabindex="0">
|
||||
|
||||
|
||||
<span class="md-ellipsis">
|
||||
|
|
@ -501,8 +463,8 @@
|
|||
<span class="md-nav__icon md-icon"></span>
|
||||
</label>
|
||||
|
||||
<nav class="md-nav" data-md-level="1" aria-labelledby="__nav_6_label" aria-expanded="false">
|
||||
<label class="md-nav__title" for="__nav_6">
|
||||
<nav class="md-nav" data-md-level="1" aria-labelledby="__nav_4_label" aria-expanded="false">
|
||||
<label class="md-nav__title" for="__nav_4">
|
||||
<span class="md-nav__icon md-icon"></span>
|
||||
Chinese
|
||||
</label>
|
||||
|
|
|
|||
|
|
@ -9,7 +9,7 @@
|
|||
|
||||
|
||||
|
||||
<link rel="prev" href="../chapter-1/">
|
||||
<link rel="prev" href="..">
|
||||
|
||||
|
||||
<link rel="next" href="../mistakes/">
|
||||
|
|
@ -289,44 +289,6 @@
|
|||
|
||||
|
||||
|
||||
|
||||
<li class="md-nav__item">
|
||||
<a href="../9-generics/" class="md-nav__link">
|
||||
|
||||
|
||||
<span class="md-ellipsis">
|
||||
Being confused about when to use generics (#9)
|
||||
</span>
|
||||
|
||||
|
||||
</a>
|
||||
</li>
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
<li class="md-nav__item">
|
||||
<a href="../chapter-1/" class="md-nav__link">
|
||||
|
||||
|
||||
<span class="md-ellipsis">
|
||||
Go: Simple to learn but hard to master
|
||||
</span>
|
||||
|
||||
|
||||
</a>
|
||||
</li>
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
|
@ -385,9 +347,9 @@
|
|||
|
||||
|
||||
|
||||
<input class="md-nav__toggle md-toggle " type="checkbox" id="__nav_6" >
|
||||
<input class="md-nav__toggle md-toggle " type="checkbox" id="__nav_4" >
|
||||
|
||||
<label class="md-nav__link" for="__nav_6" id="__nav_6_label" tabindex="0">
|
||||
<label class="md-nav__link" for="__nav_4" id="__nav_4_label" tabindex="0">
|
||||
|
||||
|
||||
<span class="md-ellipsis">
|
||||
|
|
@ -398,8 +360,8 @@
|
|||
<span class="md-nav__icon md-icon"></span>
|
||||
</label>
|
||||
|
||||
<nav class="md-nav" data-md-level="1" aria-labelledby="__nav_6_label" aria-expanded="false">
|
||||
<label class="md-nav__title" for="__nav_6">
|
||||
<nav class="md-nav" data-md-level="1" aria-labelledby="__nav_4_label" aria-expanded="false">
|
||||
<label class="md-nav__title" for="__nav_4">
|
||||
<span class="md-nav__icon md-icon"></span>
|
||||
Chinese
|
||||
</label>
|
||||
|
|
|
|||
|
|
@ -290,44 +290,6 @@
|
|||
|
||||
|
||||
|
||||
<li class="md-nav__item">
|
||||
<a href="../9-generics/" class="md-nav__link">
|
||||
|
||||
|
||||
<span class="md-ellipsis">
|
||||
Being confused about when to use generics (#9)
|
||||
</span>
|
||||
|
||||
|
||||
</a>
|
||||
</li>
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
<li class="md-nav__item">
|
||||
<a href="../chapter-1/" class="md-nav__link">
|
||||
|
||||
|
||||
<span class="md-ellipsis">
|
||||
Go: Simple to learn but hard to master
|
||||
</span>
|
||||
|
||||
|
||||
</a>
|
||||
</li>
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
<li class="md-nav__item">
|
||||
<a href="../jobs/" class="md-nav__link">
|
||||
|
||||
|
|
@ -1285,9 +1247,9 @@
|
|||
|
||||
|
||||
|
||||
<input class="md-nav__toggle md-toggle " type="checkbox" id="__nav_6" >
|
||||
<input class="md-nav__toggle md-toggle " type="checkbox" id="__nav_4" >
|
||||
|
||||
<label class="md-nav__link" for="__nav_6" id="__nav_6_label" tabindex="0">
|
||||
<label class="md-nav__link" for="__nav_4" id="__nav_4_label" tabindex="0">
|
||||
|
||||
|
||||
<span class="md-ellipsis">
|
||||
|
|
@ -1298,8 +1260,8 @@
|
|||
<span class="md-nav__icon md-icon"></span>
|
||||
</label>
|
||||
|
||||
<nav class="md-nav" data-md-level="1" aria-labelledby="__nav_6_label" aria-expanded="false">
|
||||
<label class="md-nav__title" for="__nav_6">
|
||||
<nav class="md-nav" data-md-level="1" aria-labelledby="__nav_4_label" aria-expanded="false">
|
||||
<label class="md-nav__title" for="__nav_4">
|
||||
<span class="md-nav__icon md-icon"></span>
|
||||
Chinese
|
||||
</label>
|
||||
|
|
@ -2251,6 +2213,8 @@
|
|||
<p><strong>Note:</strong> You're currently viewing a new version that I'm enriching with significantly more content. Yet, this version is still under development; please be gentle if you find an issue, and feel free to create a PR.</p>
|
||||
<!-- TODO Include full excerpts -->
|
||||
|
||||
<!-- TODO Include chapter-1.md -->
|
||||
|
||||
<p><img alt="" src="../inside-cover.png" /></p>
|
||||
<h2 id="code-and-project-organization">Code and Project Organization</h2>
|
||||
<h3 id="unintended-variable-shadowing-1">Unintended variable shadowing (#1)</h3>
|
||||
|
|
@ -2334,6 +2298,8 @@ What’s the main problem if we overuse interfaces? The answer is that they make
|
|||
<p><a href="https://github.com/teivah/100-go-mistakes/tree/master/src/02-code-project-organization/8-any/main.go">Source code</a></p>
|
||||
<h3 id="being-confused-about-when-to-use-generics-9">Being confused about when to use generics (#9)</h3>
|
||||
<p><strong>TL;DR</strong>: Relying on generics and type parameters can prevent writing boilerplate code to factor out elements or behaviors. However, do not use type parameters prematurely, but only when you see a concrete need for them. Otherwise, they introduce unnecessary abstractions and complexity.</p>
|
||||
<!-- TODO Include 9-generics.md file -->
|
||||
|
||||
<p><a href="https://github.com/teivah/100-go-mistakes/tree/master/src/02-code-project-organization/9-generics/main.go">Source code</a></p>
|
||||
<h3 id="not-being-aware-of-the-possible-problems-with-type-embedding-10">Not being aware of the possible problems with type embedding (#10)</h3>
|
||||
<p><strong>TL;DR</strong>: Using type embedding can also help avoid boilerplate code; however, ensure that doing so doesn’t lead to visibility issues where some fields should have remained hidden.</p>
|
||||
|
|
|
|||
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Reference in a new issue