error(3tcl) Tcl Built-In Commands error(3tcl)
______________________________________________________________________________
NAME
error - Generate an error
SYNOPSIS
error message ?info? ?code?
______________________________________________________________________________
DESCRIPTION
Returns a TCL_ERROR code, which causes command interpretation to be un-
wound. Message is a string that is returned to the application to in-
dicate 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 in-
formation 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 -er-
rorcode 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(3tcl), return(3tcl)
KEYWORDS
error, exception
Tcl error(3tcl)
Generated by dwww version 1.14 on Thu Jan 23 00:32:49 CET 2025.