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Teiva Harsanyi 2023-09-29 02:04:25 +02:00
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28
docs/index.md
View file

@ -535,7 +535,7 @@ It’s essential to understand how to use `==` and `!=` to make comparisons effe
* _Channels_—Compare whether two channels were created by the same call to make or if both are nil.
* _Interfaces_—Compare whether two interfaces have identical dynamic types and equal dynamic values or if both are nil.
* _Pointers_—Compare whether two pointers point to the same value in memory or if both are nil.
* _Structs and arrays)—Compare whether they are composed of similar types.
* _Structs and arrays_—Compare whether they are composed of similar types.
???+ note
@ -645,7 +645,7 @@ One essential rule to keep in mind is that a `break` statement terminates the ex
To break the loop instead of the `switch` statement, the most idiomatic way is to use a label:
```go
```go hl_lines="1 8"
loop:
for i := 0; i < 5; i++ {
fmt.Printf("%d ", i)
@ -790,7 +790,7 @@ for i, r := range s {
Or, we can convert the string into a slice of runes and iterate over it:
```go
```go hl_lines="2"
s := "hêllo"
runes := []rune(s)
for i, r := range runes {
@ -854,7 +854,7 @@ During each iteration, the `+=` operator concatenates `s` with the value string.
Fortunately, there is a solution to deal with this problem, using `strings.Builder`:
```go
```go hl_lines="2 4"
func concat(values []string) string {
sb := strings.Builder{}
for _, value := range values {
@ -944,7 +944,7 @@ A receiver _must_ be a pointer
type slice []int
func (s *slice) add(element int) {
*s = append(*s, element)
*s = append(*s, element)
}
```
@ -1085,25 +1085,13 @@ Two leading options if we want to keep using `defer`.
The first solution is to pass a string pointer:
```go
```go hl_lines="3 4"
func f() error {
var status string
defer notify(&status)
defer incrementCounter(&status)
// The rest of the function unchanged
if err := foo(); err != nil {
status = StatusErrorFoo
return err
}
if err := bar(); err != nil {
status = StatusErrorBar
return err
}
status = StatusSuccess
return nil
}
```
@ -1111,7 +1099,7 @@ Using `defer` evaluates the arguments right away: here, the address of status. Y
There’s another solution: calling a closure (an anonymous function value that references variables from outside its body) as a `defer` statement:
```go
```go hl_lines="3 4 5 6"
func f() error {
var status string
defer func() {
@ -1628,7 +1616,7 @@ ch <- 0
Then what’s the purpose of Go allowing messages to be received from or sent to a nil channel? For example, we can use nil channels to implement an idiomatic way to merge two channels:
```go
```go hl_lines="5 9 15"
func merge(ch1, ch2 <-chan int) <-chan int {
ch := make(chan int, 1)

1
mkdocs.yml
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@ -80,6 +80,7 @@ markdown_extensions:
anchor_linenums: true
line_spans: __span
pygments_lang_class: true
- pymdownx.highlight
- pymdownx.inlinehilite
- pymdownx.snippets
- pymdownx.superfences

66
site/index.html
View file

@ -3123,7 +3123,7 @@ Meanwhile, we should also look at golangci-lint (<a href="https://github.com/gol
<li><em>Channels</em>—Compare whether two channels were created by the same call to make or if both are nil.</li>
<li><em>Interfaces</em>—Compare whether two interfaces have identical dynamic types and equal dynamic values or if both are nil.</li>
<li><em>Pointers</em>—Compare whether two pointers point to the same value in memory or if both are nil.</li>
<li>_Structs and arrays)—Compare whether they are composed of similar types.</li>
<li><em>Structs and arrays</em>—Compare whether they are composed of similar types.</li>
</ul>
<details class="note" open="open">
<summary>Note</summary>
@ -3207,15 +3207,15 @@ One additional note: we must remember that the standard library has some existin
<p>The break statement doesn’t terminate the <code>for</code> loop: it terminates the <code>switch</code> statement, instead. Hence, instead of iterating from 0 to 2, this code iterates from 0 to 4: <code>0 1 2 3 4</code>.</p>
<p>One essential rule to keep in mind is that a <code>break</code> statement terminates the execution of the innermost <code>for</code>, <code>switch</code>, or <code>select</code> statement. In the previous example, it terminates the <code>switch</code> statement.</p>
<p>To break the loop instead of the <code>switch</code> statement, the most idiomatic way is to use a label:</p>
<div class="language-go highlight"><pre><span></span><code><span id="__span-11-1"><a id="__codelineno-11-1" name="__codelineno-11-1" href="#__codelineno-11-1"></a><span class="nx">loop</span><span class="p">:</span>
</span><span id="__span-11-2"><a id="__codelineno-11-2" name="__codelineno-11-2" href="#__codelineno-11-2"></a><span class="w"> </span><span class="k">for</span><span class="w"> </span><span class="nx">i</span><span class="w"> </span><span class="o">:=</span><span class="w"> </span><span class="mi">0</span><span class="p">;</span><span class="w"> </span><span class="nx">i</span><span class="w"> </span><span class="p">&lt;</span><span class="w"> </span><span class="mi">5</span><span class="p">;</span><span class="w"> </span><span class="nx">i</span><span class="o">++</span><span class="w"> </span><span class="p">{</span>
<div class="language-go highlight"><pre><span></span><code><span id="__span-11-1"><a id="__codelineno-11-1" name="__codelineno-11-1" href="#__codelineno-11-1"></a><span class="hll"><span class="nx">loop</span><span class="p">:</span>
</span></span><span id="__span-11-2"><a id="__codelineno-11-2" name="__codelineno-11-2" href="#__codelineno-11-2"></a><span class="w"> </span><span class="k">for</span><span class="w"> </span><span class="nx">i</span><span class="w"> </span><span class="o">:=</span><span class="w"> </span><span class="mi">0</span><span class="p">;</span><span class="w"> </span><span class="nx">i</span><span class="w"> </span><span class="p">&lt;</span><span class="w"> </span><span class="mi">5</span><span class="p">;</span><span class="w"> </span><span class="nx">i</span><span class="o">++</span><span class="w"> </span><span class="p">{</span>
</span><span id="__span-11-3"><a id="__codelineno-11-3" name="__codelineno-11-3" href="#__codelineno-11-3"></a><span class="w"> </span><span class="nx">fmt</span><span class="p">.</span><span class="nx">Printf</span><span class="p">(</span><span class="s">&quot;%d &quot;</span><span class="p">,</span><span class="w"> </span><span class="nx">i</span><span class="p">)</span>
</span><span id="__span-11-4"><a id="__codelineno-11-4" name="__codelineno-11-4" href="#__codelineno-11-4"></a>
</span><span id="__span-11-5"><a id="__codelineno-11-5" name="__codelineno-11-5" href="#__codelineno-11-5"></a><span class="w"> </span><span class="k">switch</span><span class="w"> </span><span class="nx">i</span><span class="w"> </span><span class="p">{</span>
</span><span id="__span-11-6"><a id="__codelineno-11-6" name="__codelineno-11-6" href="#__codelineno-11-6"></a><span class="w"> </span><span class="k">default</span><span class="p">:</span>
</span><span id="__span-11-7"><a id="__codelineno-11-7" name="__codelineno-11-7" href="#__codelineno-11-7"></a><span class="w"> </span><span class="k">case</span><span class="w"> </span><span class="mi">2</span><span class="p">:</span>
</span><span id="__span-11-8"><a id="__codelineno-11-8" name="__codelineno-11-8" href="#__codelineno-11-8"></a><span class="w"> </span><span class="k">break</span><span class="w"> </span><span class="nx">loop</span>
</span><span id="__span-11-9"><a id="__codelineno-11-9" name="__codelineno-11-9" href="#__codelineno-11-9"></a><span class="w"> </span><span class="p">}</span>
</span><span id="__span-11-8"><a id="__codelineno-11-8" name="__codelineno-11-8" href="#__codelineno-11-8"></a><span class="hll"><span class="w"> </span><span class="k">break</span><span class="w"> </span><span class="nx">loop</span>
</span></span><span id="__span-11-9"><a id="__codelineno-11-9" name="__codelineno-11-9" href="#__codelineno-11-9"></a><span class="w"> </span><span class="p">}</span>
</span><span id="__span-11-10"><a id="__codelineno-11-10" name="__codelineno-11-10" href="#__codelineno-11-10"></a><span class="w"> </span><span class="p">}</span>
</span></code></pre></div>
<p>Here, we associate the <code>loop</code> label with the <code>for</code> loop. Then, because we provide the <code>loop</code> label to the <code>break</code> statement, it breaks the loop, not the switch. Therefore, this new version will print <code>0 1 2</code>, as we expected.</p>
@ -3320,8 +3320,8 @@ One additional note: we must remember that the standard library has some existin
</span></code></pre></div>
<p>Or, we can convert the string into a slice of runes and iterate over it:</p>
<div class="language-go highlight"><pre><span></span><code><span id="__span-17-1"><a id="__codelineno-17-1" name="__codelineno-17-1" href="#__codelineno-17-1"></a><span class="nx">s</span><span class="w"> </span><span class="o">:=</span><span class="w"> </span><span class="s">&quot;hêllo&quot;</span>
</span><span id="__span-17-2"><a id="__codelineno-17-2" name="__codelineno-17-2" href="#__codelineno-17-2"></a><span class="nx">runes</span><span class="w"> </span><span class="o">:=</span><span class="w"> </span><span class="p">[]</span><span class="nb">rune</span><span class="p">(</span><span class="nx">s</span><span class="p">)</span>
</span><span id="__span-17-3"><a id="__codelineno-17-3" name="__codelineno-17-3" href="#__codelineno-17-3"></a><span class="k">for</span><span class="w"> </span><span class="nx">i</span><span class="p">,</span><span class="w"> </span><span class="nx">r</span><span class="w"> </span><span class="o">:=</span><span class="w"> </span><span class="k">range</span><span class="w"> </span><span class="nx">runes</span><span class="w"> </span><span class="p">{</span>
</span><span id="__span-17-2"><a id="__codelineno-17-2" name="__codelineno-17-2" href="#__codelineno-17-2"></a><span class="hll"><span class="nx">runes</span><span class="w"> </span><span class="o">:=</span><span class="w"> </span><span class="p">[]</span><span class="nb">rune</span><span class="p">(</span><span class="nx">s</span><span class="p">)</span>
</span></span><span id="__span-17-3"><a id="__codelineno-17-3" name="__codelineno-17-3" href="#__codelineno-17-3"></a><span class="k">for</span><span class="w"> </span><span class="nx">i</span><span class="p">,</span><span class="w"> </span><span class="nx">r</span><span class="w"> </span><span class="o">:=</span><span class="w"> </span><span class="k">range</span><span class="w"> </span><span class="nx">runes</span><span class="w"> </span><span class="p">{</span>
</span><span id="__span-17-4"><a id="__codelineno-17-4" name="__codelineno-17-4" href="#__codelineno-17-4"></a><span class="w"> </span><span class="nx">fmt</span><span class="p">.</span><span class="nx">Printf</span><span class="p">(</span><span class="s">&quot;position %d: %c\n&quot;</span><span class="p">,</span><span class="w"> </span><span class="nx">i</span><span class="p">,</span><span class="w"> </span><span class="nx">r</span><span class="p">)</span>
</span><span id="__span-17-5"><a id="__codelineno-17-5" name="__codelineno-17-5" href="#__codelineno-17-5"></a><span class="p">}</span>
</span></code></pre></div>
@ -3362,10 +3362,10 @@ One additional note: we must remember that the standard library has some existin
<p>During each iteration, the <code>+=</code> operator concatenates <code>s</code> with the value string. At first sight, this function may not look wrong. But with this implementation, we forget one of the core characteristics of a string: its immutability. Therefore, each iteration doesn’t update <code>s</code>; it reallocates a new string in memory, which significantly impacts the performance of this function.</p>
<p>Fortunately, there is a solution to deal with this problem, using <code>strings.Builder</code>:</p>
<div class="language-go highlight"><pre><span></span><code><span id="__span-21-1"><a id="__codelineno-21-1" name="__codelineno-21-1" href="#__codelineno-21-1"></a><span class="kd">func</span><span class="w"> </span><span class="nx">concat</span><span class="p">(</span><span class="nx">values</span><span class="w"> </span><span class="p">[]</span><span class="kt">string</span><span class="p">)</span><span class="w"> </span><span class="kt">string</span><span class="w"> </span><span class="p">{</span>
</span><span id="__span-21-2"><a id="__codelineno-21-2" name="__codelineno-21-2" href="#__codelineno-21-2"></a><span class="w"> </span><span class="nx">sb</span><span class="w"> </span><span class="o">:=</span><span class="w"> </span><span class="nx">strings</span><span class="p">.</span><span class="nx">Builder</span><span class="p">{}</span>
</span><span id="__span-21-3"><a id="__codelineno-21-3" name="__codelineno-21-3" href="#__codelineno-21-3"></a><span class="w"> </span><span class="k">for</span><span class="w"> </span><span class="nx">_</span><span class="p">,</span><span class="w"> </span><span class="nx">value</span><span class="w"> </span><span class="o">:=</span><span class="w"> </span><span class="k">range</span><span class="w"> </span><span class="nx">values</span><span class="w"> </span><span class="p">{</span>
</span><span id="__span-21-4"><a id="__codelineno-21-4" name="__codelineno-21-4" href="#__codelineno-21-4"></a><span class="w"> </span><span class="nx">_</span><span class="p">,</span><span class="w"> </span><span class="nx">_</span><span class="w"> </span><span class="p">=</span><span class="w"> </span><span class="nx">sb</span><span class="p">.</span><span class="nx">WriteString</span><span class="p">(</span><span class="nx">value</span><span class="p">)</span>
</span><span id="__span-21-5"><a id="__codelineno-21-5" name="__codelineno-21-5" href="#__codelineno-21-5"></a><span class="w"> </span><span class="p">}</span>
</span><span id="__span-21-2"><a id="__codelineno-21-2" name="__codelineno-21-2" href="#__codelineno-21-2"></a><span class="hll"><span class="w"> </span><span class="nx">sb</span><span class="w"> </span><span class="o">:=</span><span class="w"> </span><span class="nx">strings</span><span class="p">.</span><span class="nx">Builder</span><span class="p">{}</span>
</span></span><span id="__span-21-3"><a id="__codelineno-21-3" name="__codelineno-21-3" href="#__codelineno-21-3"></a><span class="w"> </span><span class="k">for</span><span class="w"> </span><span class="nx">_</span><span class="p">,</span><span class="w"> </span><span class="nx">value</span><span class="w"> </span><span class="o">:=</span><span class="w"> </span><span class="k">range</span><span class="w"> </span><span class="nx">values</span><span class="w"> </span><span class="p">{</span>
</span><span id="__span-21-4"><a id="__codelineno-21-4" name="__codelineno-21-4" href="#__codelineno-21-4"></a><span class="hll"><span class="w"> </span><span class="nx">_</span><span class="p">,</span><span class="w"> </span><span class="nx">_</span><span class="w"> </span><span class="p">=</span><span class="w"> </span><span class="nx">sb</span><span class="p">.</span><span class="nx">WriteString</span><span class="p">(</span><span class="nx">value</span><span class="p">)</span>
</span></span><span id="__span-21-5"><a id="__codelineno-21-5" name="__codelineno-21-5" href="#__codelineno-21-5"></a><span class="w"> </span><span class="p">}</span>
</span><span id="__span-21-6"><a id="__codelineno-21-6" name="__codelineno-21-6" href="#__codelineno-21-6"></a><span class="w"> </span><span class="k">return</span><span class="w"> </span><span class="nx">sb</span><span class="p">.</span><span class="nx">String</span><span class="p">()</span>
</span><span id="__span-21-7"><a id="__codelineno-21-7" name="__codelineno-21-7" href="#__codelineno-21-7"></a><span class="p">}</span>
</span></code></pre></div>
@ -3427,7 +3427,7 @@ One additional note: we must remember that the standard library has some existin
<div class="language-go highlight"><pre><span></span><code><span id="__span-24-1"><a id="__codelineno-24-1" name="__codelineno-24-1" href="#__codelineno-24-1"></a><span class="kd">type</span><span class="w"> </span><span class="nx">slice</span><span class="w"> </span><span class="p">[]</span><span class="kt">int</span>
</span><span id="__span-24-2"><a id="__codelineno-24-2" name="__codelineno-24-2" href="#__codelineno-24-2"></a>
</span><span id="__span-24-3"><a id="__codelineno-24-3" name="__codelineno-24-3" href="#__codelineno-24-3"></a><span class="kd">func</span><span class="w"> </span><span class="p">(</span><span class="nx">s</span><span class="w"> </span><span class="o">*</span><span class="nx">slice</span><span class="p">)</span><span class="w"> </span><span class="nx">add</span><span class="p">(</span><span class="nx">element</span><span class="w"> </span><span class="kt">int</span><span class="p">)</span><span class="w"> </span><span class="p">{</span>
</span><span id="__span-24-4"><a id="__codelineno-24-4" name="__codelineno-24-4" href="#__codelineno-24-4"></a><span class="w"> </span><span class="o">*</span><span class="nx">s</span><span class="w"> </span><span class="p">=</span><span class="w"> </span><span class="nb">append</span><span class="p">(</span><span class="o">*</span><span class="nx">s</span><span class="p">,</span><span class="w"> </span><span class="nx">element</span><span class="p">)</span>
</span><span id="__span-24-4"><a id="__codelineno-24-4" name="__codelineno-24-4" href="#__codelineno-24-4"></a><span class="w"> </span><span class="o">*</span><span class="nx">s</span><span class="w"> </span><span class="p">=</span><span class="w"> </span><span class="nb">append</span><span class="p">(</span><span class="o">*</span><span class="nx">s</span><span class="p">,</span><span class="w"> </span><span class="nx">element</span><span class="p">)</span>
</span><span id="__span-24-5"><a id="__codelineno-24-5" name="__codelineno-24-5" href="#__codelineno-24-5"></a><span class="p">}</span>
</span></code></pre></div>
<ul>
@ -3540,33 +3540,21 @@ One additional note: we must remember that the standard library has some existin
<p>The first solution is to pass a string pointer:</p>
<div class="language-go highlight"><pre><span></span><code><span id="__span-28-1"><a id="__codelineno-28-1" name="__codelineno-28-1" href="#__codelineno-28-1"></a><span class="kd">func</span><span class="w"> </span><span class="nx">f</span><span class="p">()</span><span class="w"> </span><span class="kt">error</span><span class="w"> </span><span class="p">{</span>
</span><span id="__span-28-2"><a id="__codelineno-28-2" name="__codelineno-28-2" href="#__codelineno-28-2"></a><span class="w"> </span><span class="kd">var</span><span class="w"> </span><span class="nx">status</span><span class="w"> </span><span class="kt">string</span>
</span><span id="__span-28-3"><a id="__codelineno-28-3" name="__codelineno-28-3" href="#__codelineno-28-3"></a><span class="w"> </span><span class="k">defer</span><span class="w"> </span><span class="nx">notify</span><span class="p">(</span><span class="o">&amp;</span><span class="nx">status</span><span class="p">)</span><span class="w"> </span>
</span><span id="__span-28-4"><a id="__codelineno-28-4" name="__codelineno-28-4" href="#__codelineno-28-4"></a><span class="w"> </span><span class="k">defer</span><span class="w"> </span><span class="nx">incrementCounter</span><span class="p">(</span><span class="o">&amp;</span><span class="nx">status</span><span class="p">)</span>
</span><span id="__span-28-5"><a id="__codelineno-28-5" name="__codelineno-28-5" href="#__codelineno-28-5"></a>
</span><span id="__span-28-3"><a id="__codelineno-28-3" name="__codelineno-28-3" href="#__codelineno-28-3"></a><span class="hll"><span class="w"> </span><span class="k">defer</span><span class="w"> </span><span class="nx">notify</span><span class="p">(</span><span class="o">&amp;</span><span class="nx">status</span><span class="p">)</span><span class="w"> </span>
</span></span><span id="__span-28-4"><a id="__codelineno-28-4" name="__codelineno-28-4" href="#__codelineno-28-4"></a><span class="hll"><span class="w"> </span><span class="k">defer</span><span class="w"> </span><span class="nx">incrementCounter</span><span class="p">(</span><span class="o">&amp;</span><span class="nx">status</span><span class="p">)</span>
</span></span><span id="__span-28-5"><a id="__codelineno-28-5" name="__codelineno-28-5" href="#__codelineno-28-5"></a>
</span><span id="__span-28-6"><a id="__codelineno-28-6" name="__codelineno-28-6" href="#__codelineno-28-6"></a><span class="w"> </span><span class="c1">// The rest of the function unchanged</span>
</span><span id="__span-28-7"><a id="__codelineno-28-7" name="__codelineno-28-7" href="#__codelineno-28-7"></a><span class="w"> </span><span class="k">if</span><span class="w"> </span><span class="nx">err</span><span class="w"> </span><span class="o">:=</span><span class="w"> </span><span class="nx">foo</span><span class="p">();</span><span class="w"> </span><span class="nx">err</span><span class="w"> </span><span class="o">!=</span><span class="w"> </span><span class="kc">nil</span><span class="w"> </span><span class="p">{</span>
</span><span id="__span-28-8"><a id="__codelineno-28-8" name="__codelineno-28-8" href="#__codelineno-28-8"></a><span class="w"> </span><span class="nx">status</span><span class="w"> </span><span class="p">=</span><span class="w"> </span><span class="nx">StatusErrorFoo</span>
</span><span id="__span-28-9"><a id="__codelineno-28-9" name="__codelineno-28-9" href="#__codelineno-28-9"></a><span class="w"> </span><span class="k">return</span><span class="w"> </span><span class="nx">err</span>
</span><span id="__span-28-10"><a id="__codelineno-28-10" name="__codelineno-28-10" href="#__codelineno-28-10"></a><span class="w"> </span><span class="p">}</span>
</span><span id="__span-28-11"><a id="__codelineno-28-11" name="__codelineno-28-11" href="#__codelineno-28-11"></a>
</span><span id="__span-28-12"><a id="__codelineno-28-12" name="__codelineno-28-12" href="#__codelineno-28-12"></a><span class="w"> </span><span class="k">if</span><span class="w"> </span><span class="nx">err</span><span class="w"> </span><span class="o">:=</span><span class="w"> </span><span class="nx">bar</span><span class="p">();</span><span class="w"> </span><span class="nx">err</span><span class="w"> </span><span class="o">!=</span><span class="w"> </span><span class="kc">nil</span><span class="w"> </span><span class="p">{</span>
</span><span id="__span-28-13"><a id="__codelineno-28-13" name="__codelineno-28-13" href="#__codelineno-28-13"></a><span class="w"> </span><span class="nx">status</span><span class="w"> </span><span class="p">=</span><span class="w"> </span><span class="nx">StatusErrorBar</span>
</span><span id="__span-28-14"><a id="__codelineno-28-14" name="__codelineno-28-14" href="#__codelineno-28-14"></a><span class="w"> </span><span class="k">return</span><span class="w"> </span><span class="nx">err</span>
</span><span id="__span-28-15"><a id="__codelineno-28-15" name="__codelineno-28-15" href="#__codelineno-28-15"></a><span class="w"> </span><span class="p">}</span>
</span><span id="__span-28-16"><a id="__codelineno-28-16" name="__codelineno-28-16" href="#__codelineno-28-16"></a>
</span><span id="__span-28-17"><a id="__codelineno-28-17" name="__codelineno-28-17" href="#__codelineno-28-17"></a><span class="w"> </span><span class="nx">status</span><span class="w"> </span><span class="p">=</span><span class="w"> </span><span class="nx">StatusSuccess</span>
</span><span id="__span-28-18"><a id="__codelineno-28-18" name="__codelineno-28-18" href="#__codelineno-28-18"></a><span class="w"> </span><span class="k">return</span><span class="w"> </span><span class="kc">nil</span>
</span><span id="__span-28-19"><a id="__codelineno-28-19" name="__codelineno-28-19" href="#__codelineno-28-19"></a><span class="p">}</span>
</span><span id="__span-28-7"><a id="__codelineno-28-7" name="__codelineno-28-7" href="#__codelineno-28-7"></a><span class="p">}</span>
</span></code></pre></div>
<p>Using <code>defer</code> evaluates the arguments right away: here, the address of status. Yes, status itself is modified throughout the function, but its address remains constant, regardless of the assignments. Hence, if <code>notify</code> or <code>incrementCounter</code> uses the value referenced by the string pointer, it will work as expected. But this solution requires changing the signature of the two functions, which may not always be possible.</p>
<p>There’s another solution: calling a closure (an anonymous function value that references variables from outside its body) as a <code>defer</code> statement:</p>
<div class="language-go highlight"><pre><span></span><code><span id="__span-29-1"><a id="__codelineno-29-1" name="__codelineno-29-1" href="#__codelineno-29-1"></a><span class="kd">func</span><span class="w"> </span><span class="nx">f</span><span class="p">()</span><span class="w"> </span><span class="kt">error</span><span class="w"> </span><span class="p">{</span>
</span><span id="__span-29-2"><a id="__codelineno-29-2" name="__codelineno-29-2" href="#__codelineno-29-2"></a><span class="w"> </span><span class="kd">var</span><span class="w"> </span><span class="nx">status</span><span class="w"> </span><span class="kt">string</span>
</span><span id="__span-29-3"><a id="__codelineno-29-3" name="__codelineno-29-3" href="#__codelineno-29-3"></a><span class="w"> </span><span class="k">defer</span><span class="w"> </span><span class="kd">func</span><span class="p">()</span><span class="w"> </span><span class="p">{</span>
</span><span id="__span-29-4"><a id="__codelineno-29-4" name="__codelineno-29-4" href="#__codelineno-29-4"></a><span class="w"> </span><span class="nx">notify</span><span class="p">(</span><span class="nx">status</span><span class="p">)</span>
</span><span id="__span-29-5"><a id="__codelineno-29-5" name="__codelineno-29-5" href="#__codelineno-29-5"></a><span class="w"> </span><span class="nx">incrementCounter</span><span class="p">(</span><span class="nx">status</span><span class="p">)</span>
</span><span id="__span-29-6"><a id="__codelineno-29-6" name="__codelineno-29-6" href="#__codelineno-29-6"></a><span class="w"> </span><span class="p">}()</span>
</span><span id="__span-29-7"><a id="__codelineno-29-7" name="__codelineno-29-7" href="#__codelineno-29-7"></a>
</span><span id="__span-29-3"><a id="__codelineno-29-3" name="__codelineno-29-3" href="#__codelineno-29-3"></a><span class="hll"><span class="w"> </span><span class="k">defer</span><span class="w"> </span><span class="kd">func</span><span class="p">()</span><span class="w"> </span><span class="p">{</span>
</span></span><span id="__span-29-4"><a id="__codelineno-29-4" name="__codelineno-29-4" href="#__codelineno-29-4"></a><span class="hll"><span class="w"> </span><span class="nx">notify</span><span class="p">(</span><span class="nx">status</span><span class="p">)</span>
</span></span><span id="__span-29-5"><a id="__codelineno-29-5" name="__codelineno-29-5" href="#__codelineno-29-5"></a><span class="hll"><span class="w"> </span><span class="nx">incrementCounter</span><span class="p">(</span><span class="nx">status</span><span class="p">)</span>
</span></span><span id="__span-29-6"><a id="__codelineno-29-6" name="__codelineno-29-6" href="#__codelineno-29-6"></a><span class="hll"><span class="w"> </span><span class="p">}()</span>
</span></span><span id="__span-29-7"><a id="__codelineno-29-7" name="__codelineno-29-7" href="#__codelineno-29-7"></a>
</span><span id="__span-29-8"><a id="__codelineno-29-8" name="__codelineno-29-8" href="#__codelineno-29-8"></a><span class="w"> </span><span class="c1">// The rest of the function unchanged</span>
</span><span id="__span-29-9"><a id="__codelineno-29-9" name="__codelineno-29-9" href="#__codelineno-29-9"></a><span class="p">}</span>
</span></code></pre></div>
@ -3945,18 +3933,18 @@ the use case. However, we should see the two options as complementary. </p>
</span><span id="__span-45-2"><a id="__codelineno-45-2" name="__codelineno-45-2" href="#__codelineno-45-2"></a><span class="w"> </span><span class="nx">ch</span><span class="w"> </span><span class="o">:=</span><span class="w"> </span><span class="nb">make</span><span class="p">(</span><span class="kd">chan</span><span class="w"> </span><span class="kt">int</span><span class="p">,</span><span class="w"> </span><span class="mi">1</span><span class="p">)</span>
</span><span id="__span-45-3"><a id="__codelineno-45-3" name="__codelineno-45-3" href="#__codelineno-45-3"></a>
</span><span id="__span-45-4"><a id="__codelineno-45-4" name="__codelineno-45-4" href="#__codelineno-45-4"></a><span class="w"> </span><span class="k">go</span><span class="w"> </span><span class="kd">func</span><span class="p">()</span><span class="w"> </span><span class="p">{</span>
</span><span id="__span-45-5"><a id="__codelineno-45-5" name="__codelineno-45-5" href="#__codelineno-45-5"></a><span class="w"> </span><span class="k">for</span><span class="w"> </span><span class="nx">ch1</span><span class="w"> </span><span class="o">!=</span><span class="w"> </span><span class="kc">nil</span><span class="w"> </span><span class="o">||</span><span class="w"> </span><span class="nx">ch2</span><span class="w"> </span><span class="o">!=</span><span class="w"> </span><span class="kc">nil</span><span class="w"> </span><span class="p">{</span><span class="w"> </span><span class="c1">// Continue if at least one channel isn’t nil</span>
</span><span id="__span-45-6"><a id="__codelineno-45-6" name="__codelineno-45-6" href="#__codelineno-45-6"></a><span class="w"> </span><span class="k">select</span><span class="w"> </span><span class="p">{</span>
</span><span id="__span-45-5"><a id="__codelineno-45-5" name="__codelineno-45-5" href="#__codelineno-45-5"></a><span class="hll"><span class="w"> </span><span class="k">for</span><span class="w"> </span><span class="nx">ch1</span><span class="w"> </span><span class="o">!=</span><span class="w"> </span><span class="kc">nil</span><span class="w"> </span><span class="o">||</span><span class="w"> </span><span class="nx">ch2</span><span class="w"> </span><span class="o">!=</span><span class="w"> </span><span class="kc">nil</span><span class="w"> </span><span class="p">{</span><span class="w"> </span><span class="c1">// Continue if at least one channel isn’t nil</span>
</span></span><span id="__span-45-6"><a id="__codelineno-45-6" name="__codelineno-45-6" href="#__codelineno-45-6"></a><span class="w"> </span><span class="k">select</span><span class="w"> </span><span class="p">{</span>
</span><span id="__span-45-7"><a id="__codelineno-45-7" name="__codelineno-45-7" href="#__codelineno-45-7"></a><span class="w"> </span><span class="k">case</span><span class="w"> </span><span class="nx">v</span><span class="p">,</span><span class="w"> </span><span class="nx">open</span><span class="w"> </span><span class="o">:=</span><span class="w"> </span><span class="o">&lt;-</span><span class="nx">ch1</span><span class="p">:</span>
</span><span id="__span-45-8"><a id="__codelineno-45-8" name="__codelineno-45-8" href="#__codelineno-45-8"></a><span class="w"> </span><span class="k">if</span><span class="w"> </span><span class="p">!</span><span class="nx">open</span><span class="w"> </span><span class="p">{</span>
</span><span id="__span-45-9"><a id="__codelineno-45-9" name="__codelineno-45-9" href="#__codelineno-45-9"></a><span class="w"> </span><span class="nx">ch1</span><span class="w"> </span><span class="p">=</span><span class="w"> </span><span class="kc">nil</span><span class="w"> </span><span class="c1">// Assign ch1 to a nil channel once closed</span>
</span><span id="__span-45-10"><a id="__codelineno-45-10" name="__codelineno-45-10" href="#__codelineno-45-10"></a><span class="w"> </span><span class="k">break</span>
</span><span id="__span-45-9"><a id="__codelineno-45-9" name="__codelineno-45-9" href="#__codelineno-45-9"></a><span class="hll"><span class="w"> </span><span class="nx">ch1</span><span class="w"> </span><span class="p">=</span><span class="w"> </span><span class="kc">nil</span><span class="w"> </span><span class="c1">// Assign ch1 to a nil channel once closed</span>
</span></span><span id="__span-45-10"><a id="__codelineno-45-10" name="__codelineno-45-10" href="#__codelineno-45-10"></a><span class="w"> </span><span class="k">break</span>
</span><span id="__span-45-11"><a id="__codelineno-45-11" name="__codelineno-45-11" href="#__codelineno-45-11"></a><span class="w"> </span><span class="p">}</span>
</span><span id="__span-45-12"><a id="__codelineno-45-12" name="__codelineno-45-12" href="#__codelineno-45-12"></a><span class="w"> </span><span class="nx">ch</span><span class="w"> </span><span class="o">&lt;-</span><span class="w"> </span><span class="nx">v</span>
</span><span id="__span-45-13"><a id="__codelineno-45-13" name="__codelineno-45-13" href="#__codelineno-45-13"></a><span class="w"> </span><span class="k">case</span><span class="w"> </span><span class="nx">v</span><span class="p">,</span><span class="w"> </span><span class="nx">open</span><span class="w"> </span><span class="o">:=</span><span class="w"> </span><span class="o">&lt;-</span><span class="nx">ch2</span><span class="p">:</span>
</span><span id="__span-45-14"><a id="__codelineno-45-14" name="__codelineno-45-14" href="#__codelineno-45-14"></a><span class="w"> </span><span class="k">if</span><span class="w"> </span><span class="p">!</span><span class="nx">open</span><span class="w"> </span><span class="p">{</span>
</span><span id="__span-45-15"><a id="__codelineno-45-15" name="__codelineno-45-15" href="#__codelineno-45-15"></a><span class="w"> </span><span class="nx">ch2</span><span class="w"> </span><span class="p">=</span><span class="w"> </span><span class="kc">nil</span><span class="w"> </span><span class="c1">// Assigns ch2 to a nil channel once closed</span>
</span><span id="__span-45-16"><a id="__codelineno-45-16" name="__codelineno-45-16" href="#__codelineno-45-16"></a><span class="w"> </span><span class="k">break</span>
</span><span id="__span-45-15"><a id="__codelineno-45-15" name="__codelineno-45-15" href="#__codelineno-45-15"></a><span class="hll"><span class="w"> </span><span class="nx">ch2</span><span class="w"> </span><span class="p">=</span><span class="w"> </span><span class="kc">nil</span><span class="w"> </span><span class="c1">// Assigns ch2 to a nil channel once closed</span>
</span></span><span id="__span-45-16"><a id="__codelineno-45-16" name="__codelineno-45-16" href="#__codelineno-45-16"></a><span class="w"> </span><span class="k">break</span>
</span><span id="__span-45-17"><a id="__codelineno-45-17" name="__codelineno-45-17" href="#__codelineno-45-17"></a><span class="w"> </span><span class="p">}</span>
</span><span id="__span-45-18"><a id="__codelineno-45-18" name="__codelineno-45-18" href="#__codelineno-45-18"></a><span class="w"> </span><span class="nx">ch</span><span class="w"> </span><span class="o">&lt;-</span><span class="w"> </span><span class="nx">v</span>
</span><span id="__span-45-19"><a id="__codelineno-45-19" name="__codelineno-45-19" href="#__codelineno-45-19"></a><span class="w"> </span><span class="p">}</span>

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site/sitemap.xml
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@ -2,62 +2,62 @@
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