checking for required attributes

["Shackelford, John-Mason" <Sh...@ncs.com>]

If I want to make sure that the build file doesn't actually execute if
required elements / attributes are not supplied is it an appropriate use of
Task.init() and Task.addConfiguredXXX to ensure that required fields are
populated?

I could not find any tasks that use this approach, which suggests that I am
wrong about this, but if we wait until after the parse phase is over to
check for missing attributes couldn't we be running a script that makes a
big mess because it fails mid execution due to an oversight. At best, it
wastes the user's time while a build that is bound to fail wends it way to
the fatal mistake.

Then again, perhaps I am being anal about this. I never have been terribly
put out by this behavior before.

Of course that is because I use a DTD. :p Which reminds me... will I find
good source that will tell me how to make my custom tasks contribute
accurate info to the auto generated DTD?

John-Mason Shackelford

Software Developer
NCS Pearson - Measurement Services
2510 North Dodge St.
Iowa City, IA 52245
319-354-9200x6214
shacjo@ncs.com

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Re: checking for required attributes

[Erik Hatcher <ja...@ehatchersolutions.com>]

Shackelford, John-Mason wrote:
> 
> If I want to make sure that the build file doesn't actually execute if
> required elements / attributes are not supplied is it an appropriate use of
> Task.init() and Task.addConfiguredXXX to ensure that required fields are
> populated?

I'd have to do a bit of trial-and-error on this issue myself, but you 
can throw a BuildException from the adders/setters/creators.  Many of 
Ant's tasks have such complex rules for validation that its impossible 
to check them until execute(), thats why you don't see any/many that do 
it differently.

> I could not find any tasks that use this approach, which suggests that I am
> wrong about this, but if we wait until after the parse phase is over to
> check for missing attributes couldn't we be running a script that makes a
> big mess because it fails mid execution due to an oversight.

A big mess where?  In your temporary 'build' directory?  Thats what 'ant 
clean' is for!  :))

> Of course that is because I use a DTD. :p Which reminds me... will I find
> good source that will tell me how to make my custom tasks contribute
> accurate info to the auto generated DTD?

And how do you propose to make a DTD when you use DynamicConfigurator? 
(if you are, that is) - I only made the whole DTD thing a lot tougher by 
adding the DynamicConfigurator, unfortunately.

Personally, I don't use a DTD for build.xml - its too dynamic with 
<taskdef>'s and all.

	Erik



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