[Webmacro-devel] Helping with the problems of nulls

[Marc P. <ma...@an...>]

If you're wondering why I'm bombarding the list so much at the moment 
(apologies) it's because I'm working on a real-life web site now that uses 
Ignition.

Wading through the complexitis of metadata/schema based data capture, with 
most of the problems solved by Ignition, in some places I'm encountering / 
getting bored with the same old "is it null or not before I evaluate it" 
problem.

This has probably been mentioned before, but what about something like:

#safe $myVar

Whatever you want to call #safe... but the idea is it will only evaluate 
the variable if it is not null. If it is null, it will do nothing. Diddly 
squat. You could - and this is probably stupid - extend it with an #else 
sub-directive, so it is mereley an abbreviated form of #if:

#safe $myVar
#else You have not set the variable!
#end

The advantage here over #if is that you don't need to specify a block for 
the "not null" case because the variable is your output.

The other alternative is a trivial function:

$safe($myVar, "You have not set the variable!")

Which is functionally identical. This second form is a bit nicer in usage 
because you don't have the whitespace "nuances" we've discussed with 
directives. However I like the directive syntax better if there wasn't the 
whitespace hassle:

<input name="x" value="#safe $valueOfX #else Enter a Value #end">

If something like this isn't already in the distro we should definitely add 
it. It doesn't solve all of the problems, but it would sure make some 
templates more readable and less boring to maintain!

I'm happy to write this (yes of course it's trivial) and commit it if 
people think this is worthy of WM core/options status.

Marc

-- 
Marc Palmer
Contract Java Consultant/Developer
			
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                 java and web software design
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