Magento - remove block using update XML

Question

How do I use a layout xml file to remove an already existing block? Specifically, I want to remove the block named "currency" from the block named "top.switches". It is being inserted in the directory.xml file, like this:

<default>     <reference name="top.switches">         <block type="directory/currency" name="currency" before="store_language" template="directory/currency.phtml"/>     </reference>     <reference name="head">         <block type="core/template" name="optional_zip_countries" as="optional_zip_countries" template="directory/js/optional_zip_countries.phtml" />     </reference> </default> 

Answer 1

There are two methods to remove a block defined in one layout xml file, through another xml file:

<default>     <reference name="top.switches">         <action method="unsetChild"><name>currency</name></action>     </reference> </default> 

And the way you are conventionally expected to do it:

<default>     <reference name="top.switches">         <remove name="currency" />     </reference> </default> 

You can find an explanation of the various layout xml elements here, but it doesn't cover the methods available to the action tag. For that, you need to look at the block class app/code/core/Mage/Core/Block/Abstract.php, which features all sorts of useful functions such as unsetChild, unsetCallChild, insert, sortChildren, etc.