[stringtemplate-interest] need for null test

[Terence Parr]

try a map

m ::= [ "true" : ..., "false":"<tag>false</tag>", default: "<tag nil=\"true\"/>"]

then $m.(yourTagValue)$

If that works, lemme know. i'll add to faq.

Ter
On Jan 17, 2011, at 1:30 AM, Oliver Flege wrote:

> 
> Hi,
> 
> we use an enhanced version of ST3 for xml rendering and while ST4 makes
> most of our enhancements obsolete (in particular by supporting adaptors),
> one crucial omission remains:
> 
> In order to render Boolean types declared as "xsd:boolean nillable=true" in an xsd,
> we need to distinguish between false and null values, as the output has to
> be either
> <tag>false</tag> or <tag nil="true"/>, respectively.
> 
> I couldn't find any way to express this logic using ST4's if statement
> given a Boolean attribute, as false and null both evaluate to false.
> 
> If that kind of logic can be expressed in ST4, I'd really appreciate any hint
> on how its done; otherwise I think that a "test for null"-expression should be added
> to the language, e.g., "if (?foo) ... "
> 
> 
> 
> Regards,
> Oliver
> 
> 
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