vwait(n) Tcl Built-In Commands vwait(n)_________________________________________________________________NAMEvwait - Process events until a variable is written
SYNOPSISvwait ?varName?
_________________________________________________________________DESCRIPTION
This command enters the Tcl event loop to process events,
blocking the application if no events are ready. It con-
tinues 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 han-
dler 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
Tcl 7.5 1