RuHL has a set of reserved keywords for added functionality. The intent is to keep this list to a minimum, so it is preferred to make a keyword smarter than to add a new one.

Here is the current list:

_ render _ ( Examples)

This is used in your layout and lets rule know where to inject the rendered sub content. Similar to “= yield”.

_partial ( Examples)

• Path to a partial file. RuHL must be able to find/read this file.

_if ( Examples)

• If the method returns true, processing will continue.
• If the method returns a value other than true, the inner_html of the tag will be set to that value.
• If the method returns false or nil, processing will halt and the tag will not be included on output.
• If the method returns an object that is type Enumerable, responds to empty? and empty? returns true, processing will halt and the tag will not be included on output.

_unless ( Examples)

• If the method returns true, processing will halt and the tag will not included on output.
• If the method returns false, processing will continue.

_use ( Examples)

• The object returned is used within the scope of the tag.
• If the method returns an array of objects (checks for type of Enumerable), RuHL will iteratate over the collection and render the contents of the tag against the collection item.

_use_if

• Essentially combines the logic of _if and _use so you don’t have to type more.

_swap ( Examples)

• The tag is replaced with the value of the method.