error(3Tcl)							   error(3Tcl)

NAME    [Toc]    [Back]

     error - Generate an error

SYNOPSIS    [Toc]    [Back]

     error message ?info? ?code?

DESCRIPTION    [Toc]    [Back]

     Returns a TCL_ERROR code, which causes command interpretation to be
     unwound.  Message is a string that	is returned to the application to
     indicate what went	wrong.

     If	the info argument is provided and is non-empty,	it is used to
     initialize	the global variable errorInfo.	errorInfo is used to
     accumulate	a stack	trace of what was in progress when an error occurred;
     as	nested commands	unwind,	the Tcl	interpreter adds information to
     errorInfo.	 If the	info argument is present, it is	used to	initialize
     errorInfo and the first increment of unwind information will not be added
     by	the Tcl	interpreter.  In other words, the command containing the error
     command will not appear in	errorInfo; in its place	will be	info.  This
     feature is	most useful in conjunction with	the catch command:  if a
     caught error cannot be handled successfully, info can be used to return a
     stack trace reflecting the	original point of occurrence of	the error:

	  catch	{...} errMsg
	  set savedInfo	$errorInfo
	  ...
	  error	$errMsg	$savedInfo


     If	the code argument is present, then its value is	stored in the
     errorCode global variable.	 This variable is intended to hold a machinereadable
 description of the error in cases	where such information is
     available;	see the	tclvars	manual page for	information on the proper
     format for	the variable.  If the code argument is not present, then
     errorCode is automatically	reset to ``NONE'' by the Tcl interpreter as
     part of processing	the error generated by the command.

KEYWORDS    [Toc]    [Back]

     error, errorCode, errorInfo


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