Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!sun-barr!newstop!west!runcible.West.Sun.COM!lwake
From: lwake@runcible.West.Sun.COM (Larry Wake)
Newsgroups: comp.windows.open-look
Subject: Re: XView Programming Style
Keywords: XView
Message-ID: <1552@west.West.Sun.COM>
Date: 23 Mar 91 00:06:12 GMT
References: <1991Mar13.193948.16328@sol.UVic.CA> <7207@ecs.soton.ac.uk>
Sender: news@west.West.Sun.COM
Organization: Sun Microsystems, San Diego, CA
Lines: 88

In article <7207@ecs.soton.ac.uk> mrd@ecs.soton.ac.uk (Mark Dobie) writes:
>In <1991Mar13.193948.16328@sol.UVic.CA> awatkins@lager.UVic.CA
(Andrew Watkins) writes:
>>iI have a bunch of popup window (~7) and
>>I'm adding more all the time. At present I create all of my windows
>>when the program starts up and set the visibility off for all the
>>windows I'm not using. Is this bad form? Should I create my windows as
>>they are needed and destroy them when I'm done or does it really
>>matter?
>
>Good question. This is how I do it too, but when I told my friend the
>Microsoft Windows/Presentation Manager programmer he nearly had a
>heart attack. He went on about the memory and the system resources and
>stuff. I reckon this way is neater because you can do things to the
>windows when they are invisible. Besides, creating the windows does seem
>to take a while sometimes.

In the manual "XView Version 2 Reference Manual: Converting SunView
Applications," Appendix B ("Performance Hints") says:

    "As a rule, create resources such as pop-ups only at the time they are
     required."

If you think about it, this makes a lot of sense.  For example, in an
application I'm writing there are nine windows, including the main
window, with more possibly to come.  However, I figure the average user
will use four of those with any frequency; the other four they may never
use.

As Mark mentioned above, these windows will take time to create; they'll
also consume X server resources and application memory.  So, why create
them until they're first needed?  If I don't create them all at once,
the program starts that much faster, and the time taken to create
windows is distributed equitably throughout the total execution time of
the program.

I use DevGuide quite heavily; the code I write to replace the stub
routines looks something like this:

    #include "foowin_ui.h"

    int foo_window_created = FALSE;
    foowin_frame_objects *foowin_p;

    /*
     *  Representative of a function that needs window "foo" visible.
     */
    void
    func_that_frobs_the_foo_window()
    {
	show_foo_window();
	xv_set(foowin_p->bar_item, PANEL_VALUE, "Hi there!", NULL);
	xv_set(blah blah blah);
    }

    /*
     * How we pop up window "foo" -- makes sure it exists, first
     */
    void
    show_foo_window()
    {
	if (!foo_window_created) create_foo_window();

	[ Stuff to set up a window each time it pops up goes here]

	xv_set(foowin_p->frame, XV_SHOW, TRUE, NULL);
    }

    /*
     * How we create window "foo" -- the verbosely-named function is
     * auto-generated by DevGuide and lives in foowin_ui.c
     */
    void
    create_foo_window();
    {
	foowin_p = foowin_frame_objects_initialize(base_frame, NULL);

	[code to pick up stuff DevGuide misses goes here]

	foo_window_created = TRUE;
    }

You can still do stuff to windows while they're not showing if you
want; just put the "if (!created) create_it();" construct in any
function that wants to deal with that window.
--
Larry Wake, Sun Microsystems (larry.wake@west.sun.com)
"Father McGrath!  I thought you were dead!"  "I was!"