>Alain: Whatever way you programmers feel is best is
>fine by me. Wouldn't it be better to avoid global
>variables for this recording of user-actions? I think
>that one or more new functions or properties would be
>better.
>
>get the last userAction
>get the prev userAction
>get the next userAction
>get the first userAction
Alain,
we could add a thing like this to interpreter, but internally it would
still be some sort of global, even if it doesn't pollute the scripter's
namespace for globals. But it's really not that hard.
>Alain: It depends on the action taken, doesn't it?
>>From a user's perspective, the "undo" menuItem is
>sometimes disabled (e.g. cannot undo certain actions).
>For the irreversible actions to be made reversible,
>the system will have to keep intermediate versions
>(one for each irreversible action). Please tell me
>that I am wrong.
I have to disappoint you, but you really need to keep information about
every action. Usually this is done e.g. by copying the original image into
RAM or a temp file before modifying it. When undo is initiated, it's simply
copied back. For text it's usually done similarly. So, if we just have a
way to copy text including styles somewhere where we can recover it, and
same for images, we can add undo pretty easily.
OTOH we could add undo for images and text into OpenCard itself, but this
isn't much of a problem. If you can copy and paste, you can implement undo.
>Alain: Is there some fundamental reason why the Mac
>does NOT do memmap? Why isn't it available on the Mac?
>Is the Mac the ideal platform for the development of OpenKard?
It's a rather complicated thing as the OS has to intercept every memory
access to check whether this is in real RAM or in some scrap file. Apple
just haven't gotten around to adding it to the MacOS. AFAIK it's supposed
to become part of MacOS X, but earlier versions will not support it in all
likelihood.
Cheers,
-- M. Uli Kusterer
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