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Patchwork is a PHP library that allows you to change user defined functions at runtime. This can be incredibly handy when testing. I'm by no means a Ruby expert but I heard that in the Ruby world they do this kind of stuff all the time during testing.

Here's a simple example of what Patchwork can do:

function myCounter($array)
{
    return count($array);
}

myCounter([1, 2]); // returns '2';

//now let's change the function
Patchwork\redefine('myCounter', function($array)
{
    return count($array) ? 'a lot of items' : 'empty';
});

myCounter([1, 2]); // returns 'a lot of items";

Read the implementation docs to learn how this works behind the scenes.

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At the PHP Benelux conference James Titcumb did a presentation on the BetterReflection library he's working on. You can view the slides of his presentation on SlideShare.

The BetterReflection library has a few advantages over PHP's native reflection capabilities (copied from the docs):

• you can reflect on classes that are not already loaded, without loading them
• ability to reflect on classes directly from a string of PHP code
• better Reflection analyses the DocBlocks (using phpdocumentor/type-resolver)
• reflecting directly on closures

When this pull request will get merged the library even makes it possible to monkey patch classes. Let's take a look how you would do that.

Consider this class:

class MonkeyPatchMe
{
    function getMessage() : string
    {
        return 'hello everybody';
    }
}

The body of the getMessage-function can be replaced using this code:

$classInfo = ReflectionClass::createFromName('MonkeyPatchMe');

$methodInfo = $classInfo->getMethod('getMessage');

$methodInfo->setBody(function() {
   return 'bye everybody';
});

$monkeyPatchedClass = new MonkeyPatchMe();
$monkeyPatchedClass->getMessage() // returns 'bye everybody'

Behind the scenes this voodoo works by copying the original class to another file, doing a replacement of the function body there and loading up that class.

I'll be keeping my eye on how the BetterReflection library evolves. You can read all about it's current functionality in the docs on GitHub.

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