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throw(3tcl) Tcl Built-In Commands throw(3tcl) 





NAME


throw - Generate a machine-readable error






SYNOPSIS


throw type message








DESCRIPTION


This command causes the current evaluation to be unwound with an
    error. The error created is described by the type and message
    arguments: type must contain a list of words describing the error in
    a form that is machine-readable (and which will form the error-code part of
    the result dictionary), and message should contain text that is
    intended for display to a human being.


The stack will be unwound until the error is trapped by a suitable
    catch or try command. If it reaches the event loop without
    being trapped, it will be reported through the bgerror mechanism. If
    it reaches the top level of script evaluation in tclsh, it will be
    printed on the console before, in the non-interactive case, causing an exit
    (the behavior in other programs will depend on the details of how Tcl is
    embedded and used).


By convention, the words in the type argument should go
    from most general to most specific.






EXAMPLES


The following produces an error that is identical to that produced
    by expr when trying to divide a value by zero.






throw {ARITH DIVZERO {divide by zero}} {divide by zero}








SEE ALSO


catch(3tcl), error(3tcl), errorCode(3tcl), errorInfo(3tcl),
    return(3tcl), try(3tcl)






KEYWORDS


error, exception







  

    8.6
    Tcl