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Date: Wed, 10 Nov 2010 14:23:12 +0100
Message-ID: <AANLkTimREuQOhqkie3CB0=rrNxafk9b6evcv7Q1Hr2yP@mail.gmail.com>
Subject: API question on properties
From: wolfgang haefelinger <whaefelinger@gmail.com>
To: dev@ant.apache.org
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Hello Ant Developers,

I believe the API regarding properties is incomplete (at least from a
performance point of view).

A bit of background information:
I make use of the new property API (1.8.1) which allows me to evaluate
${..} in a different way. In my case, the body ${..} will be a Java
Unified Expression (EL), see [1].

Now, EL comes with it's own object storgage and with the help of
additional tasks,  a user can create "EL properties". Assume this task
would be "<elproperty /> similar to Ant's property task. Then there
could be something like

<elproperty name=3D"p" value=3D".." />
<property name=3D"p" value=3D".." />

At this point there is a property named "p" in EL's storage and a
property named "p" in Ant's default storage.

Then, assume that  there is this <echo /> task and that "handling of
EL" has been enabled.

<echo>
   ${p}
   ${property.p}
</echo>

The first embedded ${p} resolves to the object in EL's storage, cause
PropertyEvaluators are added in LIFO order. In my case, that is
exactly what I want (in general, I believe it is better to let the
user determine the order).

However, I also want to give my users the chance to explicitly
reference the object in Ant's storage, i.e. the Ant "string" property.
That's what the second embedded reference, ${property.p} is all about.

My question is how to access to Ant property 'p' in a given project?

Obviously (?) I can't make use of Project.getUserProperty(String
propertyName) cause this would invoke my own EL property evaluator.

All I found is

 Project p =3D ...
 String name =3D 'p';
 p.getProperties().get(name);

However, a closer look to getProperties() reveals that this method is
essentially implemented as

public Hashtable getProperties() {
        //avoid concurrent modification:
        synchronized (properties) {
            return new Hashtable(properties);
        }
        // There is a better way to save the context. This shouldn't
        // delegate to next, it's for backward compatibility only.
    }

=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D
So my question is essentially how to retrieve an Ant property in Ant's stor=
age?
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D

Greetz,
Wolfgang.


[1] http://en.wikipedia.org/wiki/Unified_Expression_Language


--=20
Wolfgang H=E4felinger
h=E4felinger IT - Applied Software Architecture
http://www.haefelinger.it
+31 648 27 61 59

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