javax scripting for ant 1.7.0

Jesse Glick wrote:
> Peter Reilly wrote:
>> If the attribute is not specified a default path
will be used - all 
>> the scriptapi's that ant known about. - bsf, jsr.
> 
> So why add the API attribute at all? Just do the right
thing without 
> having to be told. Legacy scripts will expect to use
BSF and they will 
> get it. New scripts wishing to use BSF can add it to
the Ant classpath. 
> The behavior of a clean Ant installation in a clean JDK
6 installation 
> will be correct.


So if I have java6 then there's no way to get the javax
stuff is bsf is 
on the classpath. Dubious. i'd need some way of selecting an
engine

engine=bsf : bsf is mandatory
engine=javax: javax is mandatory
engine=auto :javax if found, fallback to bsf on older
systems.  (default)

This may be a 1.7.1 level change, if its done with a new
attribute and 
not a new language string.  This gives us a chance to look
at other 
aspects of scripting, to make it more useful.
  -better fault handing
  -better default values
  -ways of passing params to <scriptcondition>
conditions (and for reuse)

PS, script performance tests from the netkernel team:
http://www.ma
il-archive.com/jruby-devellists.sourceforge.net/msg01110.html

conclusion: use jython if you want speed.


> 
>> the 1.7.0 behaviour would be to find the first
script manager in the
>> classpath and to use that one. Later versions of
ant could check if a
>> particular script manager supported a particular
language and use the
>> first that "reported" that it did.
> 
> Why not just make that enhancement now? Shouldn't be
complicated, right?
> 
>> If asked for, future versions of ant could use
custom defined script
>> managers - using a JAR service specification - or
an ant task.
> 
> The purpose of the JSR is to ensure that there is a
standard for Java so 
> that no one will need to create a new script manager in
the future, and 
> ideally that usage of BSF will monotonically decrease,
so I hope Ant 
> would not need to change its behavior again.
> 
> -J.
> 


------------------------------------------------------------
---------
To unsubscribe, e-mail: dev-unsubscribeant.apache.org
For additional commands, e-mail: dev-helpant.apache.org

On 11/29/06, Steve Loughran <stevelapache.org> wrote:
> Jesse Glick wrote:
> > Peter Reilly wrote:
> >> If the attribute is not specified a default
path will be used - all
> >> the scriptapi's that ant known about. - bsf,
jsr.
> >
> > So why add the API attribute at all? Just do the
right thing without
> > having to be told. Legacy scripts will expect to
use BSF and they will
> > get it. New scripts wishing to use BSF can add it
to the Ant classpath.
> > The behavior of a clean Ant installation in a
clean JDK 6 installation
> > will be correct.
>
>
> So if I have java6 then there's no way to get the javax
stuff is bsf is
> on the classpath. Dubious. i'd need some way of
selecting an engine

exactly.
One may want to use the bsf javascript - it can use a more
up-to-date
version of rhino that that in the used by javax.
The same ant build may want to use the javax javascript.

> engine=bsf : bsf is mandatory
> engine=javax: javax is mandatory
> engine=auto :javax if found, fallback to bsf on older
systems.  (default)

This is my current thinking (except)

auto: bsf if found in the classpath, otherwise fallback to
javax. (default)
  the reason is that the user will have configured up bsf,
  and every thing works, then update to java6 and the
  script tasks stop working.

> This may be a 1.7.1 level change, if its done with a
new attribute and
> not a new language string.

Maybe, but I would still like it for 1.7.0.

> This gives us a chance to look at other
> aspects of scripting, to make it more useful.
>   -better fault handing
>   -better default values
>   -ways of passing params to <scriptcondition>
conditions (and for reuse)

These could be added in incrementally in the 1.7.* series.
One thing that is needed is evaluation support;
   something like:

  <property name="path"
language="beanshell"
eval='System.getenv("path")'/>

>
> PS, script performance tests from the netkernel team:
> http://www.ma
il-archive.com/jruby-devellists.sourceforge.net/msg01110.html
>
> conclusion: use jython if you want speed.

Mmmm ...
jython has its own problems....

Peter

>
>
> >
> >> the 1.7.0 behaviour would be to find the first
script manager in the
> >> classpath and to use that one. Later versions
of ant could check if a
> >> particular script manager supported a
particular language and use the
> >> first that "reported" that it did.
> >
> > Why not just make that enhancement now? Shouldn't
be complicated, right?
> >
> >> If asked for, future versions of ant could use
custom defined script
> >> managers - using a JAR service specification -
or an ant task.
> >
> > The purpose of the JSR is to ensure that there is
a standard for Java so
> > that no one will need to create a new script
manager in the future, and
> > ideally that usage of BSF will monotonically
decrease, so I hope Ant
> > would not need to change its behavior again.
> >
> > -J.
> >
>
>
>
------------------------------------------------------------
---------
> To unsubscribe, e-mail: dev-unsubscribeant.apache.org
> For additional commands, e-mail: dev-helpant.apache.org
>
>

------------------------------------------------------------
---------
To unsubscribe, e-mail: dev-unsubscribeant.apache.org
For additional commands, e-mail: dev-helpant.apache.org