Re: weird macro params issue

Ok, I have this working on 2.3 branch. Getting it to work in 2.4 seems  
to be a bit more involved - actually, I just need to familiarize  
myself a bit with it first. Jonathan made few assumptions in the code  
that default expressions will always evaluate at first; I need to work  
around that.

Attila.

On 2008.05.02., at 21:08, Attila Szegedi wrote:

> On 2008.05.02., at 19:43, Jonathan Revusky wrote:
>
>> I misspoke above. I meant, here, that it would be better if it always
>> worked than if it worked some of the time and failed other times. I
>> mean, it should always work or always fail... :-)
>>
>> JR
>> but I think I would just tend towards it always failing.
>
> What's funny is that I have an idea how to make it work whenever  
> possible, but making it always fail seems less trivial, as you need  
> to prove none of the default expressions actually depend on other  
> parameters; i.e. you could have an argument list of "a  
> b=someGlobalVar[a]"; you'd need to analyze the full default  
> expression of 'b' for any occurrence of 'a', and then it can be even  
> more hidden, like b=someGlobalVar[.local["a"]]; you get the idea.  
> The "always work" would however cover even these horrors naturally :-)
>
> It would have one last issue with not being deterministic with  
> existence built-ins, i.e.
>
> [#macro x a b=a c=b?default("foo")]
> ${c}
> [/#macro]
>
> [@x "bar"/]
>
> would nondeterministically print either "foo" or "bar", which can be  
> further rectified by always doing the evaluation in declaration  
> order within every iteration. I guess that would have us covered...  
> I *know* it'd be a godawful practice to use an existence builtin in  
> defaulted arg list because the engine doesn't allow you to have any  
> param be undefined, but these are still corner cases allowed by the  
> language, so we'd better address them to be deterministic...
>
> Attila.


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