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From Wascally Wabbit <>
Subject Re: Questions about new (1.8) PropertyHelper+pals...
Date Sat, 09 Jan 2010 01:42:21 GMT
 > Matt Benson wrote:
> On Jan 8, 2010, at 5:24 PM, Wascally Wabbit wrote:
>> Hello all--
>> I've just reviewed the latest Ant trunk (1.8RC1 I believe) to estimate
>> how much effort it would take to port my extensions (esp. those
>> dependent on the 1.7x PropertyHelper implementation). For this class
>> I have a few questions about current code:
> Firstly, Wabbit.... I am somewhat at a loss because I personally 
> attempted, twice if I recall correctly, to engage you on this subject 
> back when the API redesign was taking place, what, over two years ago?  
> I don't want to appear unwilling to work with you here, but... wow.  
> This could have been a lot easier then, especially considering the 
> difference in code familiarity two years makes.  In all honesty, I've 
> found a lot less time than I would like to work on OSS lately.  Ant in 
> particular (and I hope this won't offend any of my comrades) has 
> suffered neglect from many of its developers as of late; I vehemently 
> include myself among the guilty.

Yes. At least in my "neck of the woods" Maven seems to have all
the enterprise mind share now. Which is too bad as Maven is often
a painful solution to problems Ant solves easily.

>> 1) No way for an evaluator to test if it's already installed as
>> getDelegates() is protected and there is no public getEvaluators()
>> method.
> This is a fair assessment for you to have made from the API; however the 
> (base) implementation of PropertyHelper actually discards equal 
> delegates as they are installed.  We could document this fact, and 
> probably make the method final.  Would that suffice?


>> 2) Still no way to have PropertyHelpers passed through to subprojects
>> automatically (all configuration lost). [See Project.initSubproject]
> I can see how this might be desirable, but what happens when said 
> subproject installs a completely new PropertyHelper that has no idea how 
> to cope with the properties the parent project expects the subproject to 
> know how to interpret?  This would seem to want more discussion.

OK. I don't quite understand the 'properties' question. My concern
was really around the propagation of delegates (not necessarily

>> 3) Even with the current rework, installing a recursive property
>> evaluator requires that I replace the entire PropertyHelper because:
>>   1) The ParseProperties utility is created directly by the helper
>>      and that's where the algorithm basically lies. I would be nice
>>      to replace just *this* bit...
>>   2) The ParseProperties seems to be assuming a sequential walk thru
>>      the input string (it moves from left->right first getting a
>>      property name then mapping that name to a value...) Maybe I'm
>>      missing something here (I hope)?...
> I am far less familiar with the relevant code now, but a recursive 
> property evaluator is certainly possible because it exists in the 
> [props] sandbox Antlib, which we will promote to proper and release 
> shortly after Ant 1.8.0 is released.  I think perhaps what you've missed 
> is that ParseProperties is not meant to be extended by PropertyHelper 
> extensions (although I suppose in dire need it could be extended or 
> bypassed); it's simply a class which contains the algorithms for parsing 
> properties using whatever PropertyExpander delegates live in the active 
> PropertyHelper.

I'll have a look at the sandbox code then. Thanks for the pointer.

>> Any feedback would be appreciated!
> Regards,
> Matt
>> Thanks,
>> -The Wabbit

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