Grails Taglib : The template composition pattern

Grails leverages Sitemesh, a decorator engine, to support view layouts. Sitemesh layout is restricted to page layout and are not applicable to do template layout. For example a template layout which describes the composition of a table and a toolbar.

The purpose of this taglib is to define a ui composition pattern to leverage template layout.

The tags

The taglib will expose the following tags :

• ui:composition: The main tag. It takes a template attribute and it has ui:define tags as childrens.
• ui:define: The children tags. It takes a name attribute and
  a composition attribute which is a trick to create the parent<->children relationship. The body content of each ui:define tags will be used inside the ui:composition template.

The taglib

Writing taglib in Grails is a breeze on the contrary of frameworks like JSF.


Composition contains a simple map:

Example

The view

The "table" template

Conclusion

Easy!

This taglib can replace Sitemesh layout however Sitemesh provides convention over configuration for layouts and Sitemesh is in Java and therefore much faster than Groovy [1].

UI composition pattern is more generic and leverage template layout and template reusing.


[1] Mean response time for 50 concurrent thread :
benchSitemesh 0.019751053s
benchComposition 0.027618479s