在PHP闭包中注入代码

Question

I have an already defined closure and I want to inject code inside when I execute it. Here is an example:

$predefined = "print 'my predefined injected code<br />';";
$closure = function () {
  print 'hello<br />';
};
call_user_func_array($closure, array());
// output : hello

I want to mix 2 codes : a predefined one and the closure's one. After modification, I want my closure to look like this

$closure = function () {
  print 'my predefined injected code<br />';
  print 'hello<br />';
};

Is it possible to insert some code in the closure before executing it ?

Note: I can not use "create_function" that take the code as a string, so can be modified easily. The closures are already defined and are defined in a certain way (through a function that take a callback arg, not a string arg).

Thanks for your help.

---

EDIT:

Here is the solution

function hackClosure($closure, $inject_code)
{
    $reflection = new ReflectionFunction($closure);
    $tmp = $reflection->getParameters();
    $args = array();
    foreach ($tmp as $a) array_push($args, '$'.$a->getName() . ($a->isDefaultValueAvailable() ? '=\''.$a->getDefaultValue().'\'' : ''));
    $file = new SplFileObject($reflection->getFileName());
    $file->seek($reflection->getStartLine()-1);
    $code = '';
    while ($file->key() < $reflection->getEndLine())
    {
        $code .= $file->current();
        $file->next();
    }
    $start = strpos($code, '{')+1;
    $end = strrpos($code, '}');
    return create_function(implode(', ', $args), substr($code, $start, $end - $start) . $inject_code);
}

$theClosure = function () { print 'something'; };

$inject_code = "print ' to say';";

$func = hackClosure($theClosure, $inject_code);
$func();

It renders

something to say

instead of

something

Answer 1

perhaps something like this:

$closure = function($optionalcode = null) {
    print('blah blah blah');
    if (!isnull($optionalcode)) { eval($optionalcode); }
    print('blah blah blah');
}

$closure("print('yoohoo!');");

However, eval() is evil and should be avoided at all costs.