martedì, ottobre 11, 2011

Mootools AOP and how to use AOP for Profiling Mootools Classes

In my last post about Mootools private pattern mutator, I've show how to use keeto's patternmutator to inject a private object into mootools methods.
Using this private object it is then possible to add private properties and methods which are accessible only to methods decorated with 'private'.

As noted by coda in the comment section, pattern mutators is now included in mootools 2.0.
PatternMutator is also the base of my kenta.AOP Class for Mootools that I'm going to introduce, and as a bonus I will show how to use kenta.AOP to create a simple Mootools Class Profiler.
What kenta.AOP is?
kenta.AOP is simple way to handle AOP in MooTools for debugging purpose.
In particular kenta.AOP handles method invocation by rewriting all Mootools class, allowing you to intercept these methods before and after the execution.
You can then use the event parameter to cancel the method's execution or hijack the method's return value.
kenta.AOP uses Mootools Events in a Publish-Subscribe pattern to let you write any modules you want.
In this post I will show you kenta.AOP.Profile to better demonstrate what kenta.AOP can do.

I wrote kenta.AOP as a little project to better understand patternmutator and AOP myself, but since it might be useful for other people I will share this snippet. piece of code.
What kenta.AOP is not? It is not a complete AOP Framework. In particular kenta.AOP can't handle property access and it doesn't perform exception handling by design; it also overwrites all MooTools class methods, so I advise against using it for production-code :)

the complete code of kenta.AOP is here:
kenta.AOP provides a global AOP object that fire two events: 'pre' and 'post', that you can use to listen and hijack methods.
Even if kenta.AOP listens all Mootools class method, it is designed to fire only if the Class has a 'Aspect' property

I guess you are wondering what kenta.AOP can be useful for, so here's a little example of how this code can be useful for debugging:
with an example:

Since Profiling don't require to overwrite the return value I will show you another example:

and another one in which we cancel the method execution:

domenica, ottobre 09, 2011

MooTools private pattern mutator

UPDATE: I created a MooTools forge repository for Private. There you will find any kind of improvement ;) /UPDATE Not too long ago I wrote this gist to add a sort of private properties / private methods to MooTools 1.2.x:

As of MooTools 1.3 this gist won't work anymore, but I've wrote another one as alternative, it requires Mark Obcena's PatternMutators.js that you can find here: keeto.PatternMutators.js:
How it works?

In the first version, the one for the 1.2.x branch of MooTools, if you Implements Private, what happens under the hood is that it create a property using MooTools $uid to get a unique-id per istance on a not-accessible outside of Class.Mutators.Private function, then it rewrote all the method of your instance passing the associated property as the last parameter of your function so that you can use it to store/retrieve private properties or even methods.

Since there's no way to automate the cleaning of all the objects/methods you can add, it need also to add a '~' method that you need to call on your destructor so it will not leak memory. I decided to use this ugly syntax: ['~']() because it need to stand out of your code, in a way to remember you that you are using an ugly hack to create privates and because is easier to remember something so strange ;)

For the 1.3 and upper branches of MooTools(yep, still work on 1.4.x) I decided to use a different, not compatible, way to achieve the same objective, so I based my mutators on keeto's patternMutator, for a number of reasons, basically cleaner syntax, re-using of existing code (keeto's one), and only methods marked with 'private' are now overwritten. You can see an example right here:

The code is slighly different, instead of Implements:[Private], you have to explicity mark the method you would like to use private properties or methods by adding 'private ' ahead of your method name, but other things remains unchanged.