freemark（built-in） 笔记一

 default
如果存在就用本生的值，不存在就用缺省值 

<#assign seq = ['a', 'b']>
${seq[0]?default('-')}
${seq[1]?default('-')}
${seq[2]?default('-')}
${seq[3]?default('-')} 
结果

   

a
b
-
- 


   

exists

It is true if the variable exists, otherwise it is false.

has_content

It is true if the variable exists and is not ``empty'', otherwise it is false. The meaning of ``empty'' depends on the concrete case.
expr?if_exists?size > 0 or expr?if_exists?length > 0 instead of expr?has_content.

if_exists

Example. Assume no variable called mouse is present:

	(${mouse?if_exists}) Creating mouse... <#assign mouse = "Jerry"> (${mouse?if_exists})

The output will be:

	() Creating mouse... (Jerry)