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



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NAME
     error - Generate an error

SYNOPSIS
     error _m_e_s_s_a_g_e ?_i_n_f_o? ?_c_o_d_e?
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DESCRIPTION
     Returns a TCL_ERROR code, which causes  command  interpreta-
     tion to be unwound.  _M_e_s_s_a_g_e is a string that is returned to
     the application to indicate what went wrong.

     If the _i_n_f_o argument is provided and  is  non-empty,  it  is
     used to initialize the global variable errorInfo.  errorInfo
     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  _i_n_f_o
     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 con-
     taining the error command will not appear in  errorInfo;  in
     its place will be _i_n_f_o.  This feature is most useful in con-
     junction with the catch command:  if a caught  error  cannot
     be  handled successfully, _i_n_f_o 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 _c_o_d_e 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 format for the  variable.
     If  the  _c_o_d_e  argument  is  not  present, then errorCode is
     automatically reset to ``NONE'' by the  Tcl  interpreter  as
     part of processing the error generated by the command.


KEYWORDS
     error, errorCode, errorInfo









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