vwait (n)
Process events until a variable is written
SYNOPSIS
DESCRIPTION
This command enters the Tcl event loop to process events, blocking
the application if no events are ready. It continues processing
events until some event handler sets the value of variable
varName. Once varName has been set, the vwait
command will return as soon as the event handler that modified
varName completes.
In some cases the vwait command may not return immediately
after varName is set. This can happen if the event handler
that sets varName does not complete immediately. For example,
if an event handler sets varName and then itself calls
vwait to wait for a different variable, then it may not return
for a long time. During this time the top-level vwait is
blocked waiting for the event handler to complete, so it cannot
return either.
KEYWORDS
event, variable, wait
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