[stringtemplate-interest] formal arg checking

[Terence Parr]

On Apr 26, 2007, at 12:09 PM, Nate wrote:

> I assume you are proposing this...
>
> $if (errorMessage)$
>     $table(emptyMessage=errorMessage)$
> $else$
>     $table(emptyMessage="The list is empty.")$
> $endif$
>
> While this would solve my specific scenario, formal argument  
> checking is
> still flawed. I should be able to use undefined attributes when  
> applying
> a template, like this...
>
> $table(emptyMessage={$errorMessage; null="The list is empty."$})$
>
> When "errorMessage" is not defined, that code currently throws an  
> error
> saying that the attribute "errorMessage" is not a valid formal  
> argument
> for the "table" template.

Is error message defined anywhere in the surrounding context? that  
is, in an enclosing template?  If not, you cannot reference an  
undefined attribute just like in a programming language. If I were  
you, I would just add errorMessage to the template that invokes table  
and you problem disappears.

> Also, the workaround to use an IF statement is not very elegant for  
> more
> complex scenarios because it duplicates the template call. Eg...
>
> $if (errorMessage)$
>     $table(
>        emptyMessage=errorMessage,
>        rows={
>           Lots of HTML here.
>        }
>     )$
> $else$
>     $table(
>        emptyMessage="The list is empty.",
>        rows={
>           Lots of HTML here.
>        }
>     )$
> $endif$
>
> Hope you have fun on your trip!

Well, yes, but I ended up getting a cold. was at a party at my  
brother's house with 30 screaming 10-year-old boys.  As Jim Idle  
says, the probability that one of them has a nasty virus is 1. ;) The  
probability that they will do their best to give it to you is nearly  
1. ;)

Ter