在 PHP 函数中使用数组作为默认参数
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Using an array as a default parameter in a PHP function
提问by Jasdeep Khalsa
Is it possible to use an array as a default parameter in a PHP function?
是否可以在 PHP 函数中使用数组作为默认参数？
I would like to do the following:
我想做以下事情：
$arr = array(1,2,3,4);
function sample($var1, $var2, $var3 = $arr){
echo $var1.$var2;
echo print_r($var3);
}
sample('a','b');
// Should still work without the third parameter and default to $arr
回答by Ja?ck
No, this is not possible, the right hand expression of the default value must be a constant or array literal, i.e.
不，这是不可能的，默认值的右手表达式必须是常量或数组文字，即
function sample($var1, $var2, $var3 = array(1, 2, 3, 4))
{
}
If you want this behaviour, you could use a closure:
如果你想要这种行为，你可以使用闭包：
$arr = array(1, 2, 3, 4);
$sample = function ($var1, $var2, array $var3 = null) use ($arr) {
if (is_null($var3)) {
$var3 = $arr;
}
// your code
}
$sample('a', 'b');
You could also express it with a class:
你也可以用一个类来表达它：
class Foo
{
private static $arr = array(1, 2, 3, 4);
public static function bar($var1, $var2, array $var3 = null)
{
if (is_null($var3)) {
$var3 = self::$arr;
}
// your code here
}
}
Foo::bar('a', 'b');
回答by Prisoner
You can't pass $arrinto the function definition, you'll have to do:
你不能传入$arr函数定义，你必须这样做：
function sample($var1, $var2, $var3 = array('test')){
echo $var1.$var2;
echo print_r($var3);
}
sample('a','b'); // output: abArray ( [0] => test ) 1
or, if you want to be really dirty (I wouldn't recommend it..):
或者，如果你想变得很脏（我不推荐它......）：
$arr = array('test');
function sample($var1, $var2, $var3 = null){
if($var3 == null){
global $arr;
$var3 = $arr;
}
echo $var1.$var2;
echo print_r($var3);
}
sample('a','b');
回答by MAChitgarha
(It might not be a complete answer, but it covers some useful cases.) If you want to get one or more options using an array as an argument in a function (or a method), setting a default set of options might not help. Instead, you can use array_replace().
（这可能不是一个完整的答案，但它涵盖了一些有用的情况。）如果您想使用数组作为函数（或方法）中的参数获得一个或多个选项，则设置一组默认选项可能无济于事. 相反，您可以使用array_replace().
For example, let's consider a sample $optionsargument which gets an array with two keys, countand title. Setting a default value for that argument leads overriding it when using the function with any custom $optionvalue passed. In the example, if we set $optionsto have only one countkey, then the titlekey will be removed. One of the right solutions is the following:
例如，让我们考虑一个示例$options参数，它获取一个具有两个键的数组，count和title。为该参数设置默认值会导致在使用$option传递任何自定义值的函数时覆盖它。在示例中，如果我们设置$options只有一个count键，那么该title键将被删除。正确的解决方案之一如下：
function someCoolFunc($options = []) {
$options = array_replace([
"count" => 144,
"title" => "test"
], $options);
// Remained code...
}
In the example above, you will be ensured that countand titleindexes are present, even if the user supplies an empty array (keep in mind, the order of the arguments in array_replace()function is important).
在上面的示例中，您将确保存在count和title索引，即使用户提供了一个空数组（请记住，array_replace()函数中参数的顺序很重要）。
