[DrJava] BeanShell

[Peter C. <cen...@ri...>]

I just took another look at BeanShell, a java-like scripting 
environment very similar to DynamicJava.  The website is here:

<http://www.beanshell.org/>

BeanShell has recently added a few features which would be of interest 
to us for DrJava.  In particular, there is a new "Strict Java" mode, 
which forces all variable declarations to be typed and all script 
statements to have Java-legal syntax.  If I remember correctly, this 
feature has already been requested for consistency reasons for teaching 
in DrJava.  In normal mode, BeanShell will use DJ-style loose typing, 
as well as automatic boxing and unboxing of primitives and an enhanced 
print (i.e. System.out) mechanism.

Another feature that would be handy for newbies is a "global import" 
statement: "import *" which maps out the entire classpath.  Ambiguities 
in naming caused by the global import will be reported at runtime and 
can be corrected with (an) additional import statement(s).  This is 
coupled with a "which" command that prints the exact filesystem 
location of any known Java identifier.  Considering the amount of 
difficulty that new students have in understanding the classpath rules, 
this could be extremely helpful.

BeanShell already ships with a Swing-based console which integrates via 
I/O Streams or a custom interface, complete with history completion.  
We could also use a lower level of integration with the engine if we 
chose, a la DynamicJava.  Everything is LGPL, so we'd have full access 
to the code and it would be compatible with our license.

The last advantage would be consistency with other similar tools.  The 
Emacs JDE already integrates with BeanShell, and Sun is planning to use 
it in a future version of Forte and the NetBeans IDE.  As far as I can 
tell, DynamicJava is a strict subset of BeanShell, so there's little 
reason to hold out with an unpopular technology.

Obviously this would take a significant amount of work, but I think it 
would be a worthwhile venture.  What opinions are there from the other 
developers?

--
Peter