I'm positively childishly pleased to report that my simple
implementation of a history-list for a single stack or substack
works. It confines itself to that stack alone (unlike the Rev-
internal commands relevant to "recent" -- but thanks to Jacque for
her suggestions that made me learn more about those). Assuming that
each card in the relevant stack has a Back button whose mouseUp
handler just sends the command 'backButton' and a Forward button that
sends 'forwardButton', the handler's in the stack's script that I've
copied below seem to do the trick.
I don't know if anybody else needs this -- or if, as I'd be glad to
hear, there's a better way to do it. It turned out to be a pretty
design problem; the crux is what to do when the user navigates to
card *not* using the Back or Forward buttons. In that case I've opted
for deleting everything in the list after the present "Ptr" position.
This has the disadvantage of making some visited cards not accessible
through "Back". (Visit Able then Baker then Charlie, then go back to
Baker, then visit Delta. Charlie is not in the history path any
more.) Getting around that requires, as far as I can see, adding
every visit to every card (through a button or not) to the list, and
keeping a potentially very complicated tree-based set of pointers to
it. The only complete implementation of *that* kind of history I know
of is the thorough, branch-preserving Undo facility of MOTU's Digital
Performer. Certainly beyond me -- so it's a good thing it's beyond my
needs.
Charles
======== handlers for script of stack to be "historicized"
=================
global gHistList, gHistPtr, gFromButton
on preOpenStack
put empty into gHistList
put 0 into gHistPtr
put false into gFromButton
end preOpenStack
on backButton
if gHistPtr > 1 then
put true into gFromButton
subtract 1 from gHistPtr
put line gHistPtr of gHistList into tDest
go to tDest
end if
end backButton
on forwardButton
put the number of lines of gHistList into tLast
if gHistPtr < tLast then
put true into gFromButton
add 1 to gHistPtr
put line gHistPtr of gHistList into tDest
go to tDest
end if
end forwardButton
on preOpenCard
if not gFromButton then
repeat with n = the number of lines of gHistList down to
gHistPtr + 1
delete line n of gHistList
end repeat
put the name of this card & return after gHistList
add 1 to gHistPtr
end if
put false into gFromButton
if exists(btn "Back") then
disable btn "Back"
if gHistPtr > 1
then enable btn "Back"
end if
if exists(btn "Forward") then
disable btn "Forward"
if gHistPtr < the number of lines of gHistList
then enable btn "Forward"
end if
end preOpenCard
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