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error(n)                                    Tcl Built-In Commands                                   error(n)



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NAME
       error - Generate an error

SYNOPSIS
       error message ?info? ?code?
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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 initialize the  -error-info -errorinfo
       info return options and the first increment of unwind information will not be added by the Tcl inter-preter. interpreter.
       preter.  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



Tcl                                                                                                 error(n)