>
> This property controls whether or not the window owned by a stack is freed
> when the stack is closed. To provide best performance, stack windows are
> normally unmapped rather than destroyed. This property may be useful for
> those X servers with inadequate memory. This property is also useful when
> debugging external commands and functions. Externals exit when the window
> they use for communication is destroyed and are restarted when the window is
> recreated. Setting this property allows testing many versions of an external
> without having to exit MetaCard.
Right.... my understanding is that when a stack is opened, two things need to
occur (at least): the data needs to be read from the stack file on disk into
memory, and then a window is created with its definition stored in memory and a
'handle' to that window is made available. If the stack is to be displayed,
that window handle is used to draw the contents of the first card of the stack
based on the stack data that's in memory.
So there's kind of two memory chunks - one for the compressed (I'm assuming)
stack data, and one for the window handle. DestroyStack kills the first, and
destroyWindow kills the second. If you close a stack with neither property
turned on, the stack is "ignored", but both its data and its window handle
remain in memory. If you later need to reopen the stack, all LC has to do is
stop ignoring the stack data/handle and just use what's there. If you have
destroyWIndow = "true", the window handle is purged when the stack closes, but
the data remains in memory. If you have the destroyStack = "true", the data is
purged, but the window handle remains in memory.
If you close a stack with destroyStack = "false", the stack will not appear in
"the openstacks" (aka "the windows"), but it *will* appear in "the mainstacks",
as proof that it's still in memory. This has an interesting side effect with
libraries, BTW: If you 'stop using' a stack, it remains in memory even if it's
destroystack property is true - you didn't really "close" it, so it remains in
memory; to fully remove a library from memory, you need to "delete" that stack
- just make sure that the stack you're destroying is a mainstack and not a
substack, otherwise you actually delete the substack! For that reason, I tend
to use something like this:
stop using "MyLibrary"
if "MyLibrary" is among the lines of the mainstacks then delete stack
"MyLibrary"
Anyway, that's my understanding of how this stuff works - someone from the
mothership can chime in and correct where I may have messed up...
:D
Ken Ray
Sons of Thunder Software, Inc.
Email: [email protected]
Web Site: http://www.sonsothunder.com/
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