Re: "parsed" resource

[Matt Benson]

On Jan 28, 2010, at 11:19 PM, Stefan Bodewig wrote:

On 2010-01-28, Matt Benson <gudnabr...@gmail.com> wrote:

Okay, using custom PropertyEvaluators (e.g. the "types" evaluator  
from
the props antlib) we can set an attribute of a task or type to  an
arbitrary Ant type.  I would like to (after 1.8.0, I suppose) add  a
resource implementation that simply allows one to say, e.g.:

<parsedresource parse="${file(foo.txt)}" />

Now, programmatically, this type is ridiculously trivial:

public class ParsedResource extends ResourceDecorator {

  public void setParse(Resource r) {
    addConfigured(r);

If macrodef could be used to define types it could wrap around

<resourcelist>
  <string value="$${file(foo.txt)}"/>
</resourcelist>

as well.

Nice solution--I thought Peter had submitted a BZ report with a patch  
for macroing types, but I can't find it now.  I had forgotten about  
resourcelist, but it does look like what you've proposed is a capable  
solution, and gives us the ability to do what I've suggested without  
having to create anything new.


From a code perspective, this can be interpreted as simply
implementing a means of specifying the decorated resource as a bean
property, as an alternative to calling a method.  And the "parsed"
mechanism only comes into play if the user consciously chooses to
configure Ant's PropertyHelper appropriately.  So I'm searching for a
better name for this concept.

You know I'm not really into names ...

My gut feeling is that there should be a way to do it with/by  
extending
a built-in resource rather creating a new one.  And then it occured to
me that the <property> resource would be a great fit.

Maybe it would be better (from a naming perspective) if you could do

<property name="file(foo.txt)"/>

instead.  I realize this would require bigger code changes.


Yeah, quite... although I think you've identified a--I hesitate to  
say "critical", but... "indisputable"--shortcoming in the current  
PropertyResource implementation in light of the recent PropertyHelper  
changes.  I have to concede that it is perfectly reasonable to  
expect, given PropertyHelper's ability to resolve arbitrary Objects,  
that such a resolved property ought to transparently behave as the  
parsed Resource, including name and all other properties.  I will  
code this ASAP and commit when I finish or after 1.8.0 is released,  
whichever is later.  While I do think this behavior is a reasonable  
expectation once a user has thought of it, I wouldn't necessarily  
call it the most obvious think either, so another solution might  
still be in order.

The other idea I had was to add the functionality to the <resources>
resource collection, where the implementation would be as trivial as
shown in your code.

<resource add="${file(foo.txt)}"/>


Your paragraph says <resources> but your example uses <resource>; I'm  
going to assume you mean the latter.  <resource> is, of course,  
already available for using references.  A solution using this  
approach might be to make ResourceDecorator concrete, add a resource  
property setter for XML attribute accessibility, redefine a  
ResourceDecorator to, by default, refer to itself and call super  
method implementations, and replace the <resource> definition in  
types/defaults.properties to point to ResourceDecorator instead of  
Resource.  This way I think we would be able to overload the  
<resource> XML element to accept a property parsed resource in  
addition to the refid and brute-force property setting attributes  
already allowed.  But such convoluted solution, though typical of me,  
I fear may elicit some controversy, so let the games begin!  ;)

-Matt

(now add becomes the name to talk about ...)

Finally, I'd be delighted if, once a nomenclature is settled upon, if
the community said "hey, this is both trivial from a risk perspective
yet potentially quite useful--let's include it in 1.8.0!", but I
certainly won't insist upon it.  ;)

IIRC Antoine hinted he wanted to build 1.8.0 today, so it would be too
late anyway.

Stefan

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