如何将函数引用分配给变量？

Question

I would like to handle functions references and lambda in consistent way in PHP, but I have trouble when assigning a function reference to a variable.

function foo()
{
  echo "hi\n";
}

$here = function() { echo "hello\n"; };
$here = foo;

The last line gives me a warning. I could use string literal, but I am afraid of two things -- using it later as string by mistake, and problems with name resolution when passing such string-reference over namespace boundaries.

Is there any way to grab that reference without using strings?

Answer 1

One way is to create it as an anonymous function:

$foo = function()
{
  echo "hi\n";
};

$foo();