metaprogramming-javascript.js

var Aspect = Class.create();
Aspect.prototype = {
	initialize: function( clazz, before, after ) {
		var members = Object.keys( clazz.prototype );
		members.each(
			function( name ) {
				if( Object.isFunction( clazz.prototype[name] ) ) {
					var oldName = "old_" + name;
					clazz.prototype[oldName] = clazz.prototype[name];
					clazz.prototype[name] = function() {
						if ( before ) before( name );
						var me = this;
						var args = $A( arguments );
						args.each( 
							function( arg ) {
								me[oldName] = me[oldName].curry( arg );
							}
						);
						me[oldName]();
						if( after ) after( name );
					}
				}
			}
		);
	}
}

metaprogramming-javascript.usage.js

new Aspect( SampleClass, before, after );