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From Steve Loughran <>
Subject Re: javax scripting for ant 1.7.0
Date Wed, 29 Nov 2006 13:14:31 GMT
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:

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.

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