CLIM mail archive


presentation actions

>If you think you want presentation actions, you are probably wrong.

Like the textbook claim that "if you're calling EVAL, you're probably
making a mistake," this considerably overstates the case. There are
plenty of situations in which a presentation action is precisely the
right thing. Here are a few I've used that don't seem to me to be
peculiar in any way:

1. Adding a presentation menu to a mouse button. Since I often write
interfaces for naive users, I regularly redefined the mouse-right
menu. The default mouse-right menu has too many puzzling entries on it
for naive users.

2. Altering a display in the midst of entering a commmand or filling
out an accepting-values template.

3. Expanding or contracting a dynamic display (eg, a tree display).

>They are used for one thing only: performing some sort of action
>inside of the context of the input editor.  

Not true; see (2) above. Our primary use for this is to allow the user
to alter what's on the screen while s/he's filling out an
accepting-values (for instance, to expose some presentations that the
user wants to select). 

In short, there are perfectly good reasons for using presentation
actions instead of presentation translators (of whatever sort); if
CLIM is missing this facility, that oversight should be corrected.



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