你可以使用函数作为PHP中另一个函数的默认参数吗？

Can I use a function as the default value of an argument in another function? In the example below, I'm trying to use the Wordpress function get_the_title() as the default value:

function GetPageDepartment($department = get_the_title()) {
    return $department;
}

As is, the parentheses are causing a parse error. Is there a way around this, or would I have to pass the function value to a variable somewhere outside of the default values?

I know the actual code here would be largely pointless as it just returns get_the_title(), but it's just as an example, as what I actually do with the argument isn't that relevant to the question.

The answer is "no and yes, but ... yet...".
No, using PHP 5.6 you can't assign a function as a default value of a function/method.
Yes, you can assign a string and if you use that parameter/variable in a function context, i.e. echo $department();, the string will be treated as the name of a function and get_the_title() will be invoked. But... it's kinda ugly that you have to rely on the string->function name relation. Yet ... who cares?

edit: for your consideration....

<?php
function get_the_title() { return "the title"; }

function GetPageDepartment( callable $department=null ) {
    if ( null==$department ) {
        $department = 'get_the_title';
    }
    return '<'.$department().'>';
}


echo GetPageDepartment();

No you can't use this code

<?php

function get_the_title(){
    return 'this is the title';
}
$temp = get_the_title();
function GetPageDepartment($department) {
    echo $department;
}

GetPageDepartment($temp);

In the end, I plumped for:

function GetPageDepartment($department = null) {
    $department = $department ?: get_the_title(); //Sets value if null.
}

which sets the value of $department to get_the_title() if no other value's set.