Hi,
keep it simple, use the definition:
"$! is used to supress reporting an error if it does not
have a value replacing it for the empty value (null for
a set, empty string for a render)."
Remember the #invoke macro discussion to call a (bean) method
and ingore any return value. so it was sugested to do something
like:
#macro( call $foo )#set( $dummy = $foo )#end
## then
#call( $bar.method("woobie") )
which would bark if it would evaluate to null or if it does
not have a return value. I found another solution for this:
#macro( call $foo )#if( $foo )#**##end#end
I also presented a *real* usage of it as for example caching
a JDOM-loaded XML file in the session:
## in next line I don't want it to bark if it is not yet cached!
#set( $foo = $!data.Session.getAttribute("cachedXML") )
#if( !$foo )
## if it was not cached, load it here...
#set( $foo = $Xml.load("complex/file.xml") )
## cache it (ignore whatever the return value of setAttribute() is)
#call( $data.Session.setAttribute("cachedXML", $foo) )
#end
"Geir Magnusson Jr." wrote:
>
> I see what you are saying, and I understand what you need.
>
> But I wonder if we are misusing the $! as that says 'don't render the
> literal if not in the context'.
I see it more like 'don't report any errors if it does not have a value
and use the empty value (null for a set, empty string for a render)'.
>
> So do we want:
>
> 1) Status quo : don't do anything and use the logging switch? Christoph
> has a point that it isn't enough.
Would do some disturbing logs which cannot be easily be differentiated
to real problem logs.
>
> 2) Make it :
> #set ($foo = $!splarg )
> as Christoph suggests
Yup.
>
> 3) Make it :
>
> #set ( $!foo = $splarg )
>
> because you are saying don't log if the assignment to $foo is null
This would just as well do it! It could also solve the problem of:
#set ( $!foo = $notAnInteger + 1 )
But I believe this is a place where $! does not make sense (the
designer should not use it, and therefore gets a log message).
>
> 4) something else?
>
> geir
:) Christoph
