CLIM mail archive


presentation actions

    Date: Thu, 7 Feb 1991 14:05-0500
    From: Scott McKay <>

	Date: Thu, 7 Feb 1991 12:03 EST

	We were suprised to find that CLIM 0.9 did not have
	define-presentation-action, so Jeff Morrill wrote one:

    If you think you want presentation actions, you are probably wrong.
    They are used for one thing only: performing some sort of action
    inside of the context of the input editor.  The only sorts of things
    that are appropriate to do inside the input editor are (1)
    displaying menus, (2) displaying additional information that will be
    helpful in constructing commands, and (3) simple reformatting of
    displayed data (for example, the expansion of ellipses in a list of
    possibilities).  Any use of a presentation action to do something
    application specific is incorrect, and should be recast as an
    application command plus an ordinary translator.

OK, but then what is the canonical way of doing some side effect without
going through a command?  For example, suppose I wanted to have some
mosue-sensitive buttons that control what is being displayed like those
little triangle things in Mac OS 7 directory listings.  I though that
presentation actions would be the way to implement these.  Or is this
kind of usage considered to be OK?

Furthermore, I can think of reasonable interfaces where one would prefer
not to have command lines appearing at all.  For these, I would do all
the work with actions.  (I just realized you might be able to access
application commands via command translators without having some king of
echo area -- is this possible?)

And why is it a bad thing to use actions for other than the uses you

--David Gadbois

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