Tcl Built-In Commands - vwait manual page

### NAME

vwait - Process events until a variable is written

### SYNOPSIS

vwait varName

### 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

### KEYWORDS

event, variable, wait

    Copyright © 1995-1996 Sun Microsystems, Inc.
    Copyright © 1995-1997 Roger E. Critchlow Jr.