Grails : Difference between \${} and ${} -

can tell me difference between :

<g:if test="${foo.bar}"> 

and

<g:if test="\${foo.bar}"> 

a real exemple of use of "\" before "$" :

<g:if test="\${flash.message}"> 

thank you.

\${...} put literal dollar-brace output rather evaluating contents expression. have need use in normal gsp it's common in scaffolding templates template engine uses same ${} syntax own generation-time expressions generated gsp uses @ runtime - need \${} in scaffolding template generate expressions in gsp evaluated real @ runtime when page rendered.