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On Monday 03 January 2011, Mike <ipso@xxxxxxxxxxxxx> wrote: > I'm trying to design a powerful plugin system that doesn't require any > (or extremely little) modification to my existing large code base. Hook > based systems unfortunately don't seem to meet this requirement. OK, that is a design problem... > > Is something like this possible in PHP? > > //Magic function I made up, similar to __call(), > //only it replaces "new $class" with its own return value. > function __instantiate( $class, $args ) { > $plugin_class = $class.'Plugin'; > > if ( file_exists( 'plugins/'.$plugin_class.'.php' ) { > $obj = new $plugin_class($args); > return $obj; > } else { > return new $class($args); > } > } > > class MainClass { > function doSomething( $args ) { > echo "MainClass doSomething() called...\n"; > } > } > > class MainClassPlugin extends MainClass { > function doSomething( $args ) { > echo "MainClassPlugin doSomething() called...\n"; > > //Modify arguments if necessary > echo "MainClassPlugin modifying arguments...\n"; > > $retval = parent::doSomething( $args ); > > //Modify function output, or anything else required > echo "MainClassPlugin post filter...\n"; > > return $retval; > } > } > > $main_class = new MainClass(); > $main_class->doSomething( 'foo' ); > > Results: > MainClassPlugin doSomething() called... > MainClassPlugin modifying arguments... > MainClass doSomething() called... > MainClassPlugin post filter... > > I realize PHP doesn't have this magical "__instantiate" function, but > does it have any similar mechanism that would work to automatically > load alternate classes, or have a class dynamically overload > itself during runtime? Well, you can do this using abstract classes and interfaces. Also you must try the autoloader: http://php.net/manual/en/language.oop5.autoload.php Probably this will help you a lot. Best regards, -- Daniel Molina Wegener <dmw [at] coder [dot] cl> System Programmer & Web Developer Phone: +56 (2) 979-0277 | Blog: http://coder.cl/ |
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