conditionally overriding/rewriting a class in magento

I know that I can override/rewrite a model class from my module using the following syntax in the config.xml for my module.:

<config>
    <global>
        <models>
            <moduletooverride>
                <rewrite>
                    <modeltooverride>Mycompany_Mymodule_Model_Myfolder_Myclass</customer>
                </rewrite>
            </moduletooverride>
         </models>
     </global>
</config>

But what if I want this to be conditional (e.g. based on some setting in my modules adminhtml configuration section?)

Is there any syntax for this?

开发者_JS百科

Alternatively is there a way for my rewritten class to get to the class as it was before my rewrite? (to allow it to call its "predecessor".

---

There's no built in configuration option that will allow you to conditionally rewrite a class like this.

However, a rewritten class is just an extended class, so all standard OOP rules apply, including using parent:: So something like

class My_Rewritten_Class extends Class_I_Rewrote
{

    public function theMethodIRewrote($param, $options)
    {
        $original_results = parent::theMethodIRewrote($param, $options);
        if(!Mage::getStoreConfigFlag('path/to_my/on_or_off_flag'))
        {
            return $original_results
        }

        //continue with the rewrite
    }
}

Finally, although I've never tried it, you should be able to get a reference to to parsed config options with

$config->Mage::getConfig();

And then manually set or unset your rewrite option using its setOptions method.

---

There are a couple of good suggestions in this discussion: What is the best way to limit a modules functionality by store or website

In particular, this answer has a short and sweet technique that can be used for more than just store-conditionality.

---

An approach like parent::theMethodIRewrote($param, $options) is not always usable, so try the following quite simple solution:

if (!Mage::helper('mymodule')->isEnabled()){

    class My_Rewritten_Class extends Class_I_Rewrote{} //empty body - nothing rewritten

}else{

    class My_Rewritten_Class extends Class_I_Rewrote{

        public function theMethodIRewrote($param, $options){
              /* method body ... */
        }

        /* other methods ... */

    }

}

In my case (magento 1.6.0.0,php 5.3) it seems to be working.