英文:
Calling Named Argument in PHP Function
问题
我是一个Flutter开发者，我曾经使用以下函数：
String getVar({required String $a, bool $b = true}) {
if ($b) {
return $a;
} else {
return $a = 'error';
}
}
所以基本上，默认情况下，$b = 将被设置为"true"，我们可以修改它，$a 应该被填充。
调用示例：
getVar($a: 'input');
在这里，我们可以随时将 $b 设置为 false，而无需使参数的顺序与所需的函数相同：
getVar($b: false, $a: 'input');
如果这是在PHP中，我们应该像这样做：
getVar($a: 'input', $b: false);
现在，这是PHP代码，创建相同的函数：
public function getVar(String $a = '', String $b = '', bool $c = true) {
if ($c) {
return $a;
} else {
return $b;
}
}
例如，我只想设置最后一部分，也就是 $c：
$this->getVar($c=false);
主要问题是函数中将 $c 读取为 $a。
英文:
I am a flutter developer and I used to use a function for example
String getVar({required String $a,bool $b = true}) {
if($b){
return $a;
}
else{
return $a = 'error';
}
}
So basically, $b = would be set as "true" by default we can modify it and $a should be filled
Calling Example:
getVar($a: 'input');
Here we can set $b to false anytime without making the order same as the required function
getVar($b: false, $a: 'input');
if it is in php, we should do like this
getVar($a: 'input',$b: false);
Now, here is the php code, making the same function
public function getVar(String $a = '',String $b = '',bool $c = true){
if($c){
return $a;
}
else{
return $b;
}
}
For example, I just want to set the last part which is $c
$this->getVar($c=false);
The main problem is $c is read as $a in the function
答案1
得分: 3
请记住，命名参数是PHP中的一个非常新的功能。直到PHP 8之前，所有参数都是按顺序传递的。在实现中可能存在一些尚未解决的微妙之处。然而，你应该能够在PHP 8中编写以下代码：
$this->getVar(b: false, a: 'test');
看看你写的代码：
$this->getVar($b=false, $a='test');
这不是你所想的。它将本地变量 $b 设置为 false，并将false作为第一个参数传递，并将本地变量 $a 设置为字符串 'test'，然后将其作为第二个参数传递。=& 运算符已经有了预定义的含义，所以他们不得不引入 : 语法来实现命名参数。
英文:
Remember that named arguments are a very new feature in PHP. Until PHP 8, ALL arguments were passed sequentially. There may be subtleties in the implementation that have simply not been worked out. However, you should be able to write
$this->getVar(b: false, a: 'test');
in PHP 8. Looking at what you wrote:
$this->getVar($b=false, $a='test');
That doesn't do what you think. That sets the local variable $b to false, and passes false as the first parameter, and sets the local variable $a to the string 'test', and passes that as the second parameter. The '=' operator already has a predefined meaning, so they had to introduce the : syntax for named parameters.
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