NAME
error - Generate an error
SYNOPSIS
error message ?info? ?code?
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DESCRIPTION
Returns a TCL_ERROR code, which causes command interpreta
tion 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. error
Info 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 machine-readable description of the
error in cases where such information is available; see
the tclvars manual page for information on the proper for
mat for the variable. If the code argument is not pre
sent, then errorCode is automatically reset to ``NONE'' by
the Tcl interpreter as part of processing the error gener
ated by the command.
SEE ALSO
catch(n), tclvars(n)
KEYWORDS
error, errorCode, errorInfo
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