What is the "use function" expression?

Question

I saw this snippet and I dont understand why used use function array_map expression ?

<?php

namespace Project\MyProject;

use function array_map;

class MyProjectClass 
{
    protected $arr = [];
    public function __construct(array $arr)
    {
        $this->arr = array_map('trim', $arr);
    }
}

Answer 1

As mentioned in how to call global functions classes from namespace PHP:

use function array_map;

aliases a global function into the local namespace.

• This is generally unneeded.
• PHP looks up functions in the global scope anyway.
• It only makes sense if you were to redeclare a global function in the current namespace.
  • Which is somewhat of a rare situation.
  • But if you had (this is called "monkey patching") then you also wouldn't want to undermine it with use function.

The real reason use function was introduced is:

• For actually aliasing / renaming functions:

  • use function App\Helpers\my_mappymcmapface as array_map;
  • use function \trim as chomp;

• And also because PHP coders have been littering their codebases with \trim and \strpos before.

  • That was one of those unwarranted micro-performance optimizations.

So yes, for this case it's pointless decoration.