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From: swick@ATHENA.MIT.EDU (Ralph Swick)
Newsgroups: comp.windows.x
Subject: Re: arguments to action procs
Message-ID: <9012271736.AA00442@lyre.MIT.EDU>
Date: 27 Dec 90 17:36:39 GMT
References: <1990Dec26.153059.16975@bellcore.bellcore.com>
Sender: daemon@athena.mit.edu (Mr Background)
Organization: The Internet
Lines: 21


    I would like to use the params argument of an Xt action procedure to
    pass a pointer to a structure.  Is this possible?

Well, the argument is declared to be a list of Strings, and Strings
are expected to be character pointers, but in principle you could
cast any kind of pointer you wanted and include it in the list.

However, the translation table parser only understands how to generate
character strings params so the only way you could invoke an action
procedure with a different type of pointer is to call it directly in
your own code.

When translations were initially designed, some thought was given
to using full argument descriptors so that other types of action
parameters could be specified but the idea was dropped in favor
of simplicitly.

There are several ways to associate your structure pointer with
the widget id, if you really need to access dynamic data from within
the action procedure.