Re: [Jython-users] How to interrupt interpreter

[Ype K. <yk...@xs...>]

Eric,

On Tuesday 12 November 2002 12:13, Eric Jain wrote:
> Is there any way to stop an Interpreter that is executing code from wit=
hin
> a Java program? I am aware of InteractiveInterpreter.interrupt(), but t=
hat
> only seems to work for waking up blocked or sleeping threads. Having th=
e
> Interpreter regularly check whether its thread was interrupted would be=
 a
> very useful feature, as far as I am concerned!

A java thread running a jython interpreter is no more and no less than a =
java=20
thread.
Interrupting such a thread is just as difficult as interrupting a java=20
thread, because the jython interpreter does not check for thread interrup=
ted=20
status. You might extend the interpreter to do this check, but then it wo=
uld=20
run slower. Since the interpreter can call any java code that does not=20
necessarily check the interrupted status, such a check would not be a str=
ong=20
guarantee anyway.

You can use the deprecated way to stop a java thread because it is the=20
simplest; see the docs of java.lang.Thread on why you might want to avoid=
=20
this. This way is used in Console.py in the swing examples in the demo=20
directory of your jython installation.

A cleaner way is to write a function that checks for some status and call=
 it=20
at the beginning of every possibly unbound loop, ie. as the first stateme=
nt=20
in each deepest level 'while' statement. Sometimes it makes sense to use =
it=20
in deepest level 'for' statements, too.

The status check function can simply throw an exception, which you may or=
 may=20
not catch.

Anyway, make sure to use try/finally where necessary to release locks and=
/or=20
send ending signals to other waiting threads.

Have fun,
Ype