带有空格分隔参数的PHP函数

Question

What does it mean in PHP when a function's list of arguments contains a class and variable name separated by a space?

For example, in the Batchbook API sample PHP library, there is the following function declaration:

public function postPerson(Batchblue_Service_BatchBook_Person $person)

where Batchblue_Service_Batchbook_Person is a class and $person is an instance of that class.

Answer 1

That is type hinting. It means you are saying that that argument has to be an instance of that class or one of its descendent classes.

PHP 5 introduces Type Hinting. Functions are now able to force parameters to be objects (by specifying the name of the class in the function prototype) or arrays (since PHP 5.1). However, if NULL is used as the default parameter value, it will be allowed as an argument for any later call.