php 如何使用类方法作为回调函数？
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How do I use a class method as a callback function?
提问by Sandeepan Nath
If I use array_walkinside a class function to call another function of the same class
如果我array_walk在一个类函数内部使用来调用同一个类的另一个函数
class user
{
public function getUserFields($userIdsArray,$fieldsArray)
{
if((isNonEmptyArray($userIdsArray)) && (isNonEmptyArray($fieldsArray)))
{
array_walk($fieldsArray, 'test_print');
}
}
private function test_print($item, $key)
{
//replace the $item if it matches something
}
}
It gives me the following error -
它给了我以下错误 -
Warning:
array_walk()[function.array-walk]: Unable to calltest_print()- function does not exist in ...
警告：
array_walk()[function.array-walk]：无法调用test_print()- 函数不存在于 ...
So, how do I specify $this->test_print()while using array_walk()?
那么，我$this->test_print()在使用时如何指定array_walk()？
回答by Daniel Vandersluis
If you want to specify a class method as a callback, you need to specify the object it belongs to:
如果要将类方法指定为回调，则需要指定其所属的对象：
array_walk($fieldsArray, array($this, 'test_print'));
From the manual:
从手册：
A method of an instantiated object is passed as an array containing an object at index 0 and the method name at index 1.
实例化对象的方法作为数组传递，该数组包含索引 0 处的对象和索引 1 处的方法名称。
回答by Klesun
If you need to call a static method without instantiating the class you could do so:
如果您需要在不实例化类的情况下调用静态方法，您可以这样做：
// since PHP 5.3
array_walk($fieldsArray, 'self::test_print');
Or from outside:
或从外面：
// since PHP 5.5
array_walk($fieldsArray, User::class.'::test_print');
回答by Denise Ignatova
To call a class method as a callback function in another class method, you should do :
要将类方法作为另一个类方法中的回调函数调用，您应该执行以下操作：
public function compareFucntion() {
}
public function useCompareFunction() {
usort($arrayToSort, [$this, 'compareFucntion'])
}
