Parameters defaulting to another [Was: Re: fmdoc - JavaDoc-like comments for FreeMarker]

On May 17, 2008, at 0:40 , Denis wrote:

>
>> Hi Denis,
>>
>> I suppose you talking about the second parameter's default being the
>> value of the first one?
>
> Yes, but not for the reason you state.
>
> According to Jonathan
> "Just offhand, I wouldn't encourage anybody to do something like that.
> It surprised me that it worked at all, actually. I would have to look
> at the implementation. It seems to me that the default parameters
> should be evaluated in the scope of the enclosing namespace and thus,
> what Ioannis was doing should fail."
>
> I went and checked you code, and sure enough you have:
>
> <#macro label for field=for errorClass="error" code="" attributes...>
>
> Try renaming field to for, for to field...
> It may even be VM dependent unless Sun standardized string hashes for
> some reason.
>
> -- Denis.


I see. I assumed that parameter defaults would be evaluated in the  
order of declaration, as this (coincidently) matched my observations.  
So for now the only sane workaround I can think of would be:

<#macro foo bar baz="">
   <#if !baz?has_content>
     <#local baz = bar />
   </#if>
   ...
</#macro>


Is there any chance that we'll see support for that feature in a  
future release? I think it would be a valuable addition to the  
FreeMarker language.

-Felix

>
>
>> By unreliable you mean that this will lead to
>> unexpected results when there is a variable called "bar" in the same
>> (or global) namespace? If this is the case, is there a more reliable
>> way to do it?
>>
>> Thanks for pointing this out,
>> -Felix
>>
>>
>> On May 16, 2008, at 3:33 , Denis wrote:
>>
>>> Hi Felix
>>>
>>> Does your library rely on the undocumented, unreliable
>>>
>>> <#macro foo bar baz=bar>
>>> ?
>>>
>>> -- Denis. 
>>>
>>
>
> -------------------------------------------------------------------------
> This SF.net email is sponsored by: Microsoft
> Defy all challenges. Microsoft(R) Visual Studio 2008.
> http://clk.atdmt.com/MRT/go/vse0120000070mrt/direct/01/
> _______________________________________________
> FreeMarker-user mailing list
> [email protected]
> https://lists.sourceforge.net/lists/listinfo/freemarker-user


-------------------------------------------------------------------------
This SF.net email is sponsored by: Microsoft 
Defy all challenges. Microsoft(R) Visual Studio 2008. 
http://clk.atdmt.com/MRT/go/vse0120000070mrt/direct/01/