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







error - Generate an error








error message ?info? ?code?












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 -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.








Generate an error if a basic mathematical operation fails:




if {1+2 != 3} {


    error "something is very wrong with addition"
}












catch(n), return(n)










error







  

    
    Tcl