Added a constructor to structs

This commit is contained in:
PeterBocan 2019-07-01 16:45:01 +02:00
parent 46fe6bc6cb
commit c127e2898e
4 changed files with 61 additions and 4 deletions

View File

@ -12,6 +12,16 @@ type person struct {
age int
}
// A de facto constructor of type `person`.
func NewPerson(name string) *person {
// You can safely return a pointer to local variable
// as a local variable will survive the scope of the function.
p := person{name: name}
p.age = 42
return &p
}
func main() {
// This syntax creates a new struct.
@ -38,4 +48,7 @@ func main() {
// Structs are mutable.
sp.age = 51
fmt.Println(sp.age)
// Call our constructor
fmt.Println(NewPerson("Jon"))
}

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@ -1,2 +1,2 @@
49cad39331ee5e9fb8d8dad99d3aff7f18a4e6d0
XMZpGsF4sWM
71e8ecdcf8c8fbddbb250ada5bbe8659b68d5229
nHvnHAGTYHq

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@ -6,3 +6,4 @@ $ go run structs.go
Sean
50
51
&{Jon 42}

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@ -29,7 +29,7 @@ records.</p>
</td>
<td class="code leading">
<a href="http://play.golang.org/p/XMZpGsF4sWM">
<a href="http://play.golang.org/p/nHvnHAGTYHq">
<img title="Run code" class="run" src="data:image/png;base64,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" />
</a>
<div class="highlight"><pre><span class="kn">package</span> <span class="nx">main</span>
@ -66,6 +66,36 @@ records.</p>
</td>
</tr>
<tr>
<td class="docs">
<p>A de facto constructor of type <code>person</code>.</p>
</td>
<td class="code leading">
<div class="highlight"><pre><span class="kd">func</span> <span class="nx">NewPerson</span><span class="p">(</span><span class="nx">name</span> <span class="kt">string</span><span class="p">)</span> <span class="o">*</span><span class="nx">person</span> <span class="p">{</span>
</pre></div>
</td>
</tr>
<tr>
<td class="docs">
<p>You can safely return a pointer to local variable
as a local variable will survive the scope of the function.</p>
</td>
<td class="code leading">
<div class="highlight"><pre> <span class="nx">p</span> <span class="o">:=</span> <span class="nx">person</span><span class="p">{</span><span class="nx">name</span><span class="p">:</span> <span class="nx">name</span><span class="p">}</span>
<span class="nx">p</span><span class="p">.</span><span class="nx">age</span> <span class="p">=</span> <span class="mi">42</span>
<span class="k">return</span> <span class="o">&amp;</span><span class="nx">p</span>
<span class="p">}</span>
</pre></div>
</td>
</tr>
<tr>
<td class="docs">
@ -164,10 +194,23 @@ pointers are automatically dereferenced.</p>
<p>Structs are mutable.</p>
</td>
<td class="code">
<td class="code leading">
<div class="highlight"><pre> <span class="nx">sp</span><span class="p">.</span><span class="nx">age</span> <span class="p">=</span> <span class="mi">51</span>
<span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="nx">sp</span><span class="p">.</span><span class="nx">age</span><span class="p">)</span>
</pre></div>
</td>
</tr>
<tr>
<td class="docs">
<p>Call our constructor</p>
</td>
<td class="code">
<div class="highlight"><pre> <span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="nx">NewPerson</span><span class="p">(</span><span class="s">&quot;Jon&quot;</span><span class="p">))</span>
<span class="p">}</span>
</pre></div>