Working of snippets
Snippets are units of code that can be called from a resource or a template.
A snippet can do one or more of the following three things:
Return text or HTML
Populate template variables
Process a chunk and return its value
Almost anything that can be done in PHP can be done using a snippet. However, how you control the output and the flexibility of the snippet depends on how you use the snippet to do one of the preceding activities or a combination of them.
A snippet can be called by using one of the following notations:
[[snippetname]]—cached call[!snippetname!]—non-cached call
In a cached call, a snippet is processed once, and whatever it generates is cached and used till the cache is cleared. However, if the page from which the snippet is executed is not cached, the snippet will be processed anyway for every request. Caching may be useful for optimization in situations where the expected output from the snippet does not change frequently.
In a non-cached call, a snippet is processed...
