Path: utzoo!attcan!uunet!samsung!think!mintaka!bloom-beacon!ATHENA.MIT.EDU!swick
From: swick@ATHENA.MIT.EDU (Ralph R. Swick)
Newsgroups: comp.windows.x
Subject: Re: Defining Callbacks from resource files
Message-ID: <8912191502.AA22891@LYRE.MIT.EDU>
Date: 19 Dec 89 15:02:09 GMT
References: <38@guug.UUCP>
Sender: daemon@athena.mit.edu (Mr Background)
Organization: DEC/MIT Project Athena
Lines: 24


    I am having a problem setting up callback functions from a resource file.
    ...
    X Toolkit Warning: No type converter registered for 'String' to 'Callback'
    conversion.


Not too surprising.  While not impossible to accomplish, writing a
procedure which would permit you to specify real function names
in a resource file requires a considerable amount of operating-system-
specific support.  It has not been implemented (nor is it documented
to be implemented or likely to be implemented in the near future :-)
in any MIT release.

To allow portable specification of procedure bindings in resource
files, Xt provides another facility very similar to callbacks known
as Action procedures.  See chapter 10 of the Xt document.  While
not a replacement for callbacks, action procedures are most
definitely intended to be used to do what you want:

    I would like to be able to choose which function is called from a particular
    menu item at run time and not compile it into the program. 

-Ralph R. Swick