throw(n) Tcl Built-In Commands throw(n)
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 dis-
play 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 gen-
eral 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(n), error(n), errorCode(n), errorInfo(n), return(n), try(n)
KEYWORDS
error, exception
Tcl 8.6 throw(n)
tcl 8.6.1 - Generated Tue Oct 1 07:43:28 CDT 2013