类型提示和默认参数值是否也是方法签名？

Question

Example : The interface is

public function doFoo($bar);

Can I have a class implementing the interface with method

public function doFoo(array $bar = array('test')) { }

What does the method signature mean in PHP?

Is it just the method name and parameter name ? Or, type hinting and default values for parameters also included ?

Answer 1

The default value for an argument isn't fixed with a interface (To clarify: The value isn't fixed, but if the interface has a default value then the class which implements the interface also needs a default value, but the value is not fixed by the interface).

However when an interface defines a method with a type hint the class must use the same type hint! You can also see this in the manual.

And a quote from there:

An interface, together with type-hinting, provides a good way to make sure that a particular object contains particular methods. See instanceof operator and type hinting.