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improve calc error code system

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Added help/errorcodes rule to the top level Makefile.

Added E_USERMAX symbol (== 32767) to indicate the maximum value
allowed for user error codes.

Improve help/error.  Added text about error code ranges and
range symbols.
This commit is contained in:
Landon Curt Noll
2023-09-12 14:08:49 -07:00
parent 4c65986502
commit 19819340ff
6 changed files with 105 additions and 17 deletions
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89
help/error
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@@ -5,30 +5,97 @@ SYNOPSIS
error([n])
TYPES
n integer, 0 <= n <= 32767; defaults to errno()
n integer, defaults to errno()
return null value or error value
DESCRIPTION
If n == 0:
If n is zero, error(n) returns the null value.
error(n) returns the null value.
For positive n, error(n) returns a value of error type n.
The "global calc_errno value" is set to 0.
error(n) sets calc_errno to n so that until another error-value
is returned by some function, errno() will return the value n.
The global calc error count is not changed.
For 0 < n <= 32767:
error(n) returns a value that is of a special type called
"error". The "error" return value, when given to iserror()
will cause that function to return a true value that happens
to match the "global calc_errno value".
The "global calc_errno value" is then set to n.
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.
All other values of n are reserved for future use and currently
will generate an error.
The term "global calc_errno value" is an internal calc state.
This is NOT a calc variable called calc_errno.
The "global calc_errno value" be set to some other non-zero
value by other builtin functions and calculations, especially
if they result in an error. Thus, while calling errno(n) may
set calc_errno, some other error may later overwrite the
"global calc_errno value".
By convention, the "global calc_errno value" has the following ranges:
n < 0 Reserved for future use
n == 0 calc_errno cleared: libc errno codes above here
1 <= n <= 9999 system error and libc errno codes
n == 10000 Reserved for "No error" calc internal state
10001 <= n <= E__HIGHEST calc computation error codes
E__HIGHEST < n < 20000 Reserved for future calc error codes
20000 < n <= 32767 User defined error codes start here
n >= 32768 Reserved for future use
The following constants are part of the calc error code mechanism:
E__BASE == 10000
E_USERDEF == 20000
E_USERMAX == 32767
E__BASE < E__HIGHEST < E_USERDEF
E__COUNT == E__HIGHEST - E__BASE
See help errorcodes for the actual values of the above constants.
EXAMPLE
; errmax(errcount()+1)
20
; errcount(0),; errmax(20),;
; print errcount(), errmax()
0 20
; a = error(10009)
; a
Error 10009
; print errcount(), errmax()
1 20
; print a
Error 10009
; print iserror(a)
10009
; strerror(a)
"Bad argument for inverse"
; b = error(0)
; print errcount(), errmax()
1 20
; print isnull(b)
1
LIMITS
none
0 <= n <= 32767
LINK LIBRARY
none
@@ -37,7 +104,7 @@ SEE ALSO
errcount, errmax, errorcodes, iserror, errno, strerror, newerror,
stoponerror
## Copyright (C) 1999-2006 Landon Curt Noll
## 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