Could using local.xml lead to another outcome than using one of the default layout .xml files?

Question

EDIT: I decided to rephrase my original question, trying to make it a more general question.

I'm trying two options to achieve the same result, but they turn out differently... I'm working in Magento's DEFAULT package and apart from the two options that I will describe below, everyting else in my configuration is left the same.

Here are my two options:

• Option 1: Using catalog.xml to apply a change

  I copied app/design/frontend/BASE/default/layout/catalog.xml to app/design/frontend/DEFAULT/default/layout/ and changed line 285 from:

  <block type="catalog/product_view_type_configurable" name="product.info.options.configurable" as="options_configurable" before="-" template="catalog/product/view/type/options/configurable.phtml"/>
  

  into this:

  <block type="catalog/product_view_type_configurable" name="product.info.options.configurable" as="options_configurable" before="-" template="catalog/product/view/type/options/configurable.phtml">
      <block type="core/text_list" name="product.info.options.configurable.renderers" as="attr_renderers" />
      <block type="core/text_list" name="product.info.options.configurable.after" as="after" />
  </block>
  

  This option 1 leads to the following result (the result that I need)

  

• Option 2: Using layout.xml trying to apply the same change

  I have not copied and modified catalog.xml but instead created app/design/frontend/DEFAULT/default/layout/local.xml which is fully working. In this file I have added the following code:

  <layout>
  
      ....
  
      <PRODUCT_TYPE_configurable>
  
          <reference name="product.info.options.configurable">
  
              <block type="core/text_list" name="product.info.options.configurable.renderers" as="attr_renderers" />
              <block type="core/text_list" name="product.info.options.configurable.after" as="after" />
  
          </reference>
  
      </PRODUCT_TYPE_configurable>
  
  </layout>
  

  In my view (please correct me if I'm wrong) this is the only correct way to add the block instances product.info.options.configurable.renderers and product.info.options.configurable.after to the block instance product.info.options.configurable (which in this Option 2 comes from app/design/frontend/BASE/default/layout/catalog.xml).

  This option 2 however leads to the following result (not the result that I need)

  

I have checked everything multiple times and this really sums up my two options which lead to different results. I would expect them to lead to the same result (unless the code I added to local.xml is incorrect).

So my question basically comes down to this: Could it be possible that using local.xml leads to another result than doing the exact same thing by using one of the default layout .xml files (e.g. catalog.xml)?

Answer 1

I haven't checked for your case, so the answer is more general.

Could it be possible that using local.xml leads to another result than doing the exact same thing by using one of the default layout .xml files (e.g. catalog.xml)?

Yes.

Because the loading order of the files is changed. If you try to <reference> a block which doesn't exist yet, you can't do anything with it. No <action>, no new <block> inside, etc.

To avoid this, you have a few options:

1. use another layout handle, which is processed later.
2. <depend> on the module which creates the block, so your file is loaded after catalog.xml.
3. Use local.xml which is loaded last.