Template Toolkit, Default and Zero

marvell has asked for the wisdom of the Perl Monks concerning the following question:

Esteemed colleagues ...

I am using Template Toolkit and have an included component with a snippet of the form:

[% DEFAULT n = 1 %]

[% x = f(n) %]
[download]

This works well unless I need to set n = 0:

[% INCLUDE snippet n=0 %]
[download]

At which point the default value is chosen.

My question, therefore, is ... is there a way of getting this to work without having to resort to this?

[% DEFAULT n = 1 %]
[% IF z = 1; n = 0; END %]
[% x = f(n) %]
[download]

[% INCLUDE snippet z=1 %]
[download]

Your time and efforts, as always, are appreciated.

--
Steve Marvell

Comment on Template Toolkit, Default and Zero Select or Download Code

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Re: Template Toolkit, Default and Zero by dtr (Scribe) on Aug 30, 2006 at 13:02 UTC
Quoting from the Template::Manual::Directives perldoc page on the DEFAULT directive:- The DEFAULT directive is similar to SET but only updates variables that are currently undefined or have no "true" value (in the Perl sense). The following seems to work though:- `[% UNLESS n.defined && n.length; n = 1; END %]`	[reply] [d/l]
Re^2: Template Toolkit, Default and Zero by marvell (Pilgrim) on Aug 30, 2006 at 13:31 UTC
Though not required, could this be turned into a MACRO? -- Steve Marvell	[reply]
Re^2: Template Toolkit, Default and Zero by marvell (Pilgrim) on Aug 30, 2006 at 13:23 UTC
That worked nothing less that perfectly as a replacement for DEFAULT. Thanks. -- Steve Marvell	[reply]
Re: Template Toolkit, Default and Zero by davidrw (Prior) on Aug 30, 2006 at 21:31 UTC
did i over simplify, or does this work for you? `[% x = f( z == 1 ? 0 : 1 ) %]` [download] Also note that besides the ternary operator you can also use the "reverse" condition syntax, just like perl... e.g. `[$ SET n = 0 IF z = 1 %]` is valid TT syntax.	[reply] [d/l] [select]