Rick McGuire wrote:
2009/4/2 Rony G. Flatscher rony.flatsc...@wu-wien.ac.at:
Hi there,
in news:comp.lang.rexx Erik Duijs posted a problem that relates to an
RXSIO exit.
Use-case:
Using BSF4Rexx a Java program dispatches a Rexx script, which in turn uses
Java to dispatch another Rexx program in the same thread. Each dispatch of a
Rexx program from the Java side has currently the following logic:
RexxRegisterExitExe(..) is used to register an RXSIO exit handler for the
UserArea argument a local character array is used which gets data stuffed
into it in a FIFO-fashion,
RexxStart(...) gets a RXSYSEXIT list supplied that denotes that RXSIO exit
handler,
RexxDeregisterExit() is used to deregister the RXSIO exit handler.
Running under ooRexx 3.2 the invocation of another Rexx script via Java from
the first Rexx script fails upon returning to the first Rexx script and
writing something to stdout.
However, running the same program under the latest build of ooRexx 4.0 will
correctly run the program. It seems that ooRexx 4.0 is able to distinguish
the RexxDerigsterExit() from each other (whereas in the ooRexx 3.2 case it
seems that deregistering affects both interpreter instances and causes the
exit failure by ooRexx).
The different in 4.0 is how Rexx is using the registered exit
information. In 3.2.0, the exit handler was queried on each call to
the handler, so deregistering the handler will cause an error, as you
observed. In 4.0, the information about the handlers is resolved once
at the RexxStart initial startup, and that entry point information is
used for all calls. Deregistering the handler has no effect.
The question would be: can one rely on ooRexx 4.0 to deregister the matching
(nested) exit handler?
No, the interpreter never deregisters a handler.
A second question: removing the RexxDerigsterExit(...) from the code allows
the programs to run correctly under both, 3.2 and 4.0. Are there any
side-effects one should consider if not deregistering the (continuously)
registered exit handlers?
It depends on the type of hander being registered. If you are using
RexxRegisterExitExe() (which you seem to be), then all of those exits
will be deregistered when the process that registeres them terminates.
If you're using the DLL form, then they are persistent.
Thank you very much, indeed!
---rony
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