error(n) Tcl Built-In Commands error(n)
NAME
error - Generate an error
SYNOPSIS
error message ?info? ?code?
DESCRIPTION
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.
The -errorinfo return option of an interpreter 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 the -errorinfo
return option. If the info argument is present, it is used to initial-
ize the -errorinfo return options 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 the stack
trace; in its place will be info. Historically, this feature had been
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
When working with Tcl 8.5 or later, the following code should be used
instead:
catch {...} errMsg options ... return -options $options $errMsg
If the code argument is present, then its value is stored in the
-errorcode return option. The -errorcode return option is intended to
hold a machine-readable description of the error in cases where such
information is available; see the return manual page for information on
the proper format for this option's value.
EXAMPLE
Generate an error if a basic mathematical operation fails:
if {1+2 != 3} {
error "something is very wrong with addition" }
SEE ALSO
catch(n), return(n)
KEYWORDS
error, exception
Tcl error(n)
tcl 8.6.0 - Generated Tue Jan 8 16:13:20 CST 2013