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Preserving Parameters for Window Procedures

IP.com Disclosure Number: IPCOM000107812D
Original Publication Date: 1992-Mar-01
Included in the Prior Art Database: 2005-Mar-22
Document File: 1 page(s) / 47K

Publishing Venue

IBM

Related People

Weber, OW: AUTHOR

Abstract

This article describes a method of preserving the parameters of a window procedure in an OS/2* Presentation Manager* (PM) application program. The parameters passed to a window procedure are fixed, i.e., a handle, a message, and two message parameters, but the window procedure needs to be able to use the parameters passed to the associated main procedure.

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Preserving Parameters for Window Procedures

       This article describes a method of preserving the
parameters of a window procedure in an OS/2* Presentation Manager*
(PM) application program.  The parameters passed to a window
procedure are fixed, i.e., a handle, a message, and two message
parameters, but the window procedure needs to be able to use the
parameters passed to the associated main procedure.

      Consider the following scenario:  An application program calls
a PM program called APROC.  APROC is a main procedure, and it creates
a window whose associated window procedure is AWINPROC.  The
application passed parameter APARAM to APROC, and that parameter is
needed in AWINPROC as well, but the only parameters for a window
procedure are a handle, a message, and two message parameters.  Since
APARAM cannot be passed as a parameter to AWINPROC, one would like to
be able to store it in persistent storage.  However, this is not
possible either, since the key for the persistent storage is the
handle of the client window to be created. In other words, APROC
needs the persistent storage key to be able to preserve APARAM there
before the new client window is created, and AWINPROC needs the
APARAM before it allocates the persistent storage, so the result is a
stalemate.  This article describes a new method which will enable
both programs to preserve the necessary data.

      The new method of preserving the data includes several steps.
First of all, w...