NAME
    newerror - create or recall a user defined error condition

SYNOPSIS
    newerror([str])

TYPES
    str         string

    return      error-value

DESCRIPTION
    If str is not "" and has not earlier been used as an argument for
    this function, newerror(str) creates a new described error-value so
    that any future use of newerror(str) with the same str will return
    the same error-value.

    When this function is called, the  global calc error count (see
    help errcount) is incremented.  If the global calc error count
    exceeds the maximum count (see help errmax), any ongoing calc
    execution is aborted.

    If x = newerror(str), both strerror(x) and strerror(iserro(x)) will
    return str and iserror(x) will return the error code value of the
    new error.

    The null cases newerror() and newerror("") are equivalent to
    newerror("???").

EXAMPLE
    Note that by default, errmax() is 0 so unless errmax() is
    increased you will get:

    ; ba = newerror("curds n' whey");
    Error 20000 caused errcount to exceed errmax

    ; errmax(errcount()+5)
            0
    ; e1 = newerror("triangle side length <= 0")
    ; iserror(e1)
            20000
    ; error(20000)
            Error E_20000
    ; strerror(error(20000))
            "triangle side length <= 0"
    ; strerror(e1);
            "triangle side length <= 0"
    ; strerror(error(iserror(e1)))
            "triangle side length <= 0"

    ; define area(a,b,c) {
    ;;  local s;
    ;;  if (!(a > 0) || !(b > 0) || !(c > 0)) return e1;
    ;;  s = (a + b + c)/2;
    ;;  if (s <= a || s <= b || s <= c) return newerror("Non-triangle sides");
    ;;  return sqrt(s * (s - a) * (s - b) * (s - c));
    ;; }
    "area" defined

    ; A = area(8,2,5);
    ; if (iserror(A)) print strerror(A) : ":", iserror(A);
    Non-triangle sides: 20001

    ; A = area(-3,4,5)
    ; if (iserror(A)) print strerror(A) : ":", iserror(A);
    triangle side length <= 0: 20000

LIMITS
    The number of new described error-values is not to exceed E__USERMAX-E__USERDEF
    (which is usually 12767 calls to the newerror function).

LINK LIBRARY
    none

SEE ALSO
    errcount, errmax, errno, errorcodes, errsym, iserror, stoponerror, strerror

## Copyright (C) 1999-2006,2023  Landon Curt Noll
##
## Calc is open software; you can redistribute it and/or modify it under
## the terms of the version 2.1 of the GNU Lesser General Public License
## as published by the Free Software Foundation.
##
## Calc is distributed in the hope that it will be useful, but WITHOUT
## ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
## or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Lesser General
## Public License for more details.
##
## A copy of version 2.1 of the GNU Lesser General Public License is
## distributed with calc under the filename COPYING-LGPL.  You should have
## received a copy with calc; if not, write to Free Software Foundation, Inc.
## 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
##
## Under source code control:   1996/04/30 03:39:56
## File existed as early as:    1996
##
## chongo <was here> /\oo/\     http://www.isthe.com/chongo/
## Share and enjoy!  :-)        http://www.isthe.com/chongo/tech/comp/calc/
