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From: brianw@gazooch.Sun.COM (Brian Warkentine)
Newsgroups: comp.windows.x
Subject: Re: Defining Callbacks from resource files
Message-ID: <129425@sun.Eng.Sun.COM>
Date: 19 Dec 89 18:45:23 GMT
References: <38@guug.UUCP> <8912191502.AA22891@LYRE.MIT.EDU>
Sender: news@sun.Eng.Sun.COM
Reply-To: brianw@sun.UUCP (Brian Warkentine)
Organization: Sun Microsystems, Mountain View
Lines: 31

In article <8912191502.AA22891@LYRE.MIT.EDU> swick@ATHENA.MIT.EDU (Ralph R. Swick) writes:
>
>    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.
> [ ... ]
>To allow portable specification of procedure bindings in resource
>files, Xt provides another facility very similar to callbacks known
>as Action procedures.  
>-Ralph R. Swick


	You're contradicting yourself.  Since one can already bind action proc 
	names to "real functions", why would it be operating system dependent 
	to bind callback names to "real functions?"

	Suppose that callbacks could be registered in a fashion similar 
	to action proc registration.  The difference is subtle but its a 
	win:  A user could specify a callback in .Xdefaults (or where ever)
	without having to worry about what sequence of events are required 
	to trigger that callback.

-brian warkentine
brianw@sun.com