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From: GBODSO1@NUSVM.BITNET (HC Eng)
Newsgroups: comp.lang.ada
Subject: MOTIF BINDING
Message-ID: <9009060654.AA09349@ajpo.sei.cmu.edu>
Date: 10 Sep 90 15:32:00 GMT
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X-Unparsable-Date: Thu, 06 Sep 90 14:42:15 SST

Please refer to the item in Vol 90 Issue 168 about JPL coming up with
a Motif binding.  (Please note that I am very new to Ada.)  In the OSF Motif
toolkit, widgets are treated as objects and callbacks are passed as subprogram
pointers.  I am dying to know how this could be implemented in Ada since Ada
does not have a subprogram type.
Presently I am coding my own "Motif" toolkit in Ada for the IBM RS/6000 and
the stumbling block is the lack of the subprogram type (see Ada LI65).  I am
solving the problem very unsatisfactorily by making the interface layer call
a procedure CALLBACK(W) where W is the widget being activated.  Inside CALLBACK
is a giant IF and ELSIF block to cater for every widget declared in my program.
It is unsatisfactory because everytime I add a new widget, I must amend this
block.
Therefore, if there is something that I don't know that would make the Motif
binding possible, I would be very happy to hear it immediately.