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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  com-plete, complete,
       plete, so it cannot return either.


SEE ALSO
       global(n)


KEYWORDS
       event, variable, wait



Tcl                                                  8.0                                            vwait(n)