Set a default value to property.

Discussion:

ritchie

2010-11-30 19:04:17 UTC

My ant script takes a value for a property at runtime(-Denv=xxx), if the
argument is not passed i want the value to be set as a default arbitary
value. How to accomplish this?

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Scot P. Floess

2010-11-30 19:11:45 UTC

Permalink

Here is something I like to use... I macrodef'd it out so I can call it
for many properties that require default values...

<macrodef name="default">
<attribute name="property"/>
<attribute name="default"/>
<attribute name="description" default=""/>

<sequential>
<condition property="@{property}" value="@{default}">
<not>
<isset property="@{name}"/>
</not>
</condition>
</sequential>
</macrodef>

This works with stock Ant (meaning you don't need Ant-contrib or any third
party libraries)...

To use:

<default property="SomeProperty" default="Some Default Value"/>

Post by ritchie
My ant script takes a value for a property at runtime(-Denv=xxx), if the
argument is not passed i want the value to be set as a default arbitary
value. How to accomplish this?

--
Scot P. Floess

RHCT (Certificate Number 605010084735240)

Chief Architect FlossWare http://sourceforge.net/projects/flossware
http://flossware.sourceforge.net
https://github.com/organizations/FlossWare

Chief Architect JPlate http://sourceforge.net/projects/jplate
Chief Architect JavaPIM http://sourceforge.net/projects/javapim
Chief Architect Keros http://sourceforge.net/projects/keros

Scot P. Floess

2010-11-30 19:20:45 UTC

Permalink

Clearly my snippet is wrong:

<macrodef name="default">
<attribute name="property"/>
<attribute name="default"/>
<attribute name="description" default=""/>

<sequential>
<condition property="@{property}" value="@{default}">
<not>
<isset property="@{property}"/>
</not>
</condition>
</sequential>
</macrodef>

----- Call to <isset> was using the wrong attribute

Here is something I like to use... I macrodef'd it out so I can call it for
many properties that require default values...
<macrodef name="default">
<attribute name="property"/>
<attribute name="default"/>
<attribute name="description" default=""/>
<sequential>
<not>
</not>
</condition>
</sequential>
</macrodef>
This works with stock Ant (meaning you don't need Ant-contrib or any third
party libraries)...
<default property="SomeProperty" default="Some Default Value"/>

Post by ritchie
My ant script takes a value for a property at runtime(-Denv=xxx), if the
argument is not passed i want the value to be set as a default arbitary
value. How to accomplish this?

Alexander Enrique Urieles Nieto

2010-11-30 19:24:53 UTC

Permalink

What may it be wrong about simply using:

<project name="Foo" default="foo" basedir=".">
<property name="bar" value="default"/>
<target name="foo" description="foo">
<echo message="${bar}" />
</target>
</project>

Since properties are immutable and if it was set in the command line
call it won't change?

Best regards,

Alexander.

<macrodef name="default">
<attribute name="property"/>
<attribute name="default"/>
<attribute name="description" default=""/>
<sequential>
<not>
</not>
</condition>
</sequential>
</macrodef>
----- Call to <isset> was using the wrong attribute

Here is something I like to use... I macrodef'd it out so I can call it
for many properties that require default values...
<macrodef name="default">
<attribute name="property"/>
<attribute name="default"/>
<attribute name="description" default=""/>
<sequential>
<not>
</not>
</condition>
</sequential>
</macrodef>
This works with stock Ant (meaning you don't need Ant-contrib or any third
party libraries)...
<default property="SomeProperty" default="Some Default Value"/>

My ant script takes a value for a property at runtime(-Denv=xxx), if the
argument is not passed i want the value to be set as a default arbitary
value. How to accomplish this?

--
Scot P. Floess
RHCT (Certificate Number 605010084735240)
Chief Architect FlossWare http://sourceforge.net/projects/flossware
http://flossware.sourceforge.net
https://github.com/organizations/FlossWare
Chief Architect JPlate http://sourceforge.net/projects/jplate
Chief Architect JavaPIM http://sourceforge.net/projects/javapim
Chief Architect Keros http://sourceforge.net/projects/keros
---------------------------------------------------------------------

Niklas Matthies

2010-11-30 19:25:37 UTC

Permalink

How is this different from just

<property name="SomeProperty" value="Some Default Value"/>

?

-- Niklas Matthies

Post by Scot P. Floess
Here is something I like to use... I macrodef'd it out so I can call it
for many properties that require default values...
<macrodef name="default">
<attribute name="property"/>
<attribute name="default"/>
<attribute name="description" default=""/>
<sequential>
<not>
</not>
</condition>
</sequential>
</macrodef>
This works with stock Ant (meaning you don't need Ant-contrib or any
third party libraries)...
<default property="SomeProperty" default="Some Default Value"/>

Post by ritchie
My ant script takes a value for a property at runtime(-Denv=xxx), if the
argument is not passed i want the value to be set as a default arbitary
value. How to accomplish this?

--
Scot P. Floess
RHCT (Certificate Number 605010084735240)
Chief Architect FlossWare http://sourceforge.net/projects/flossware
http://flossware.sourceforge.net
https://github.com/organizations/FlossWare
Chief Architect JPlate http://sourceforge.net/projects/jplate
Chief Architect JavaPIM http://sourceforge.net/projects/javapim
Chief Architect Keros http://sourceforge.net/projects/keros
---------------------------------------------------------------------

Scot P. Floess

2010-11-30 19:30:53 UTC

Permalink

Actually, nothing at all... I swear at one time I thought a warning was
emitted when doing that... It was at that time I started using the
enclosed macrodef... Perhaps I am just remembering wrong...

Post by Niklas Matthies
How is this different from just
<property name="SomeProperty" value="Some Default Value"/>
?
-- Niklas Matthies

Post by ritchie
My ant script takes a value for a property at runtime(-Denv=xxx), if the
argument is not passed i want the value to be set as a default arbitary
value. How to accomplish this?

--
Scot P. Floess
RHCT (Certificate Number 605010084735240)
Chief Architect FlossWare http://sourceforge.net/projects/flossware
http://flossware.sourceforge.net
https://github.com/organizations/FlossWare
Chief Architect JPlate http://sourceforge.net/projects/jplate
Chief Architect JavaPIM http://sourceforge.net/projects/javapim
Chief Architect Keros http://sourceforge.net/projects/keros
---------------------------------------------------------------------

---------------------------------------------------------------------

Niklas Matthies

2010-11-30 20:00:06 UTC

Permalink

I don't think this (emitting a warning) was ever the case. Setting and
overriding defaults this way is one of the basic techniques in Ant. It
should probably be made more explicit in the manual.

-- Niklas Matthies

Post by Scot P. Floess
Actually, nothing at all... I swear at one time I thought a warning was
emitted when doing that... It was at that time I started using the
enclosed macrodef... Perhaps I am just remembering wrong...

Post by Niklas Matthies
How is this different from just
<property name="SomeProperty" value="Some Default Value"/>
?
-- Niklas Matthies

Post by ritchie
My ant script takes a value for a property at runtime(-Denv=xxx), if the
argument is not passed i want the value to be set as a default arbitary
value. How to accomplish this?

Scot P. Floess

2010-11-30 20:05:47 UTC

Permalink

Honestly, its quite possible I am remembering wrong...

I'm looking over some of my old code...it looks like I wanted to emit a
warning if overriding - its me...again ;)

Post by Niklas Matthies
I don't think this (emitting a warning) was ever the case. Setting and
overriding defaults this way is one of the basic techniques in Ant. It
should probably be made more explicit in the manual.
-- Niklas Matthies

Post by Niklas Matthies
How is this different from just
<property name="SomeProperty" value="Some Default Value"/>
?
-- Niklas Matthies

Post by ritchie
My ant script takes a value for a property at runtime(-Denv=xxx), if the
argument is not passed i want the value to be set as a default arbitary
value. How to accomplish this?

---------------------------------------------------------------------

ritchie

2010-11-30 21:04:51 UTC

Permalink

Thanks all for your replies, i tried some thing like this and it worked.

<property name = "version" value="23"/>
...
..
<replacefilter token="${XYZ}" value="${version}"/>

and when i ran the command ant -Dversion=25 it worked. Actually my ant task
is replacing a regular expression with the version value. When i dont pass
the arguments -Dversion=xxx it sets the token value as 23.

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View this message in context: http://ant.1045680.n5.nabble.com/Set-a-default-value-to-property-tp3286574p3286768.html
Sent from the Ant - Users mailing list archive at Nabble.com.

David Weintraub

2010-11-30 19:44:36 UTC

Permalink

Post by ritchie
My ant script takes a value for a property at runtime(-Denv=xxx), if the
argument is not passed i want the value to be set as a default arbitary
value. How to accomplish this?

What do you mean "arbitrary" value? Do you mean some value that you
chose, or it should chose some value on its own, either from a list or
at random?

If you simply want a default property, just set a property in your build.xml.

There's a hierarchy of where property values are set. If you include a
properties file, the values there override whatever values you set in
the build.xml itself, and values from the command line overrided
values set in both the build.xml and property files.

I do this all the time:


<property name="env" value="some_value"/>

--
David Weintraub
***@gmail.com