vwait(n) Tcl Built-In Commands vwait(n)
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NAME
vwait - Process events until a variable is written
SYNOPSIS
vwait varName
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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. varName must globally scoped (either with a call to global for the varName, or with the full
namespace path specification).
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.
SEE ALSO
global(n)
KEYWORDS
event, variable, wait
Tcl 8.0 vwait(n)
