添加参数覆盖方法E_STRICT观察 [英] adding parameters to overriden method E_STRICT observation

问题描述

出现（PHP 5.3），如果你覆盖一个类方法，它可以添加额外的参数，只要它们有默认值。

It appears (PHP 5.3) that if you are overriding a class method, it is okay to you can add additional parameters, as long as they have default values.

例如，考虑类：

class test1 {
  public function stuff() {
    echo "Hi";
  }
}

以下类扩展了test1 E_STRICT警告。

The following class extends "test1" and will produce an E_STRICT warning.

class test2 extends test1 {
  public function stuff($name) {
    echo "Hi $name";
  }
}

但是，以下不产生E_STRICT警告。

But, the following does not produce an E_STRICT warning.

class test3 extends test1 {
  public function stuff($name = "") {
    echo "Hi $name";
  }
}

虽然test3类不产生E_STRICT警告，我一直以来的印象是，PHP不允许方法签名被重载覆盖。所以，我要问。

While class "test3" doesn't produce an E_STRICT warning, I have been under the impression that PHP does not allow method signatures to be overloaded overridden. So, I have to ask. Is my observation a bug/flaw or actually correct intended behavior?

此外，如果默认参数参数是一个错误/缺陷，

Further, if a default argument parameter is okay, why is a non-default argument parameter not okay?

推荐答案

如果您添加了非默认参数， -defaulted参数到重写的方法，子类不再满足超类定义的契约。你不能正确地调用test2-> stuff（），因为这个方法现在需要一个参数 - 但超类说你应该能够调用它没有一个。因此，E_STRICT警告。

If you add a non-defaulted parameter to an overridden method, the subclass no longer satisfies the contract defined by the superclass. You cannot correctly call test2->stuff(), because this method now expects a parameter - but the superclass says you should be able to call it without one. Hence the E_STRICT warning.

如果你添加一个默认的参数，你仍然可以调用test3-> stuff（）（从你的例子）所以合同没有破损。事实上，通过添加可选参数，您只需扩展它。

If you add a defaulted parameter though, you can still call test3->stuff() (from your example) - as the superclass expects - and so the contract is not broken. In fact, by adding the optional parameter, you have simply extended it.

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