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Some folks might think: “you still use RCS”?!? And we will say, hey, at least we switched from SCCS to RCS back in … I think it was around 1994 ... at least we are keeping up! :-) :-) :-) Logs say that SCCS version 18 became RCS version 19 on 1994 March 18. RCS served us well. But now it is time to move on. And so we are switching to git. Calc releases produce a lot of file changes. In the 125 releases of calc since 1996, when I started managing calc releases, there have been 15473 file mods!
118 lines
3.9 KiB
Plaintext
118 lines
3.9 KiB
Plaintext
NAME
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custom - custom builtin interface
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SYNOPSIS
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custom([custname [, arg ...]])
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TYPES
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custname string
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arg any
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return any
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DESCRIPTION
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This function will invoke the custom function interface. Custom
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functions are accessed by the custname argument. The remainder
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of the args, if any, are passed to the custom function. The
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custom function may return any value, including null. Calling
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custom with no args is equivalent to the command 'show custom'.
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In order to use the custom interface, two things must happen:
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1) Calc must be built to allow custom functions. By default,
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the master Makefile is shipped with ALLOW_CUSTOM= -DCUSTOM
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which causes custom functions to be compiled in.
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2) Calc must be invoked with an argument of -C as in:
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calc -C
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In other words, explicit action must be taken in order to
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enable the use of custom functions. By default (no -C arg)
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custom functions are compiled in but disabled so that only
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portable calc scripts may be used.
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The main focus for calc is to provide a portable platform for
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multi-precision calculations in a C-like environment. You should
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consider implementing algorithms in the calc language as a first
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choice. Sometimes an algorithm requires use of special hardware, a
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non-portable OS or pre-compiled C library. In these cases a custom
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interface may be needed.
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The custom function interface is intended to make is easy for
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programmers to add functionality that would be otherwise
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un-suitable for general distribution. Functions that are
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non-portable (machine, hardware or OS dependent) or highly
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specialized are possible candidates for custom functions.
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To add a new custom function requires access to calc source.
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For information on how to add a new custom function, try:
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help new_custom
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To serve as examples, calc is shipped with a few custom functions.
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If calc if invoked with -C, then either of the following will
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display information about the custom functions that are available:
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show custom
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or:
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custom()
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A few resource files that uses these function are also provided
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to serve as usage examples.
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We welcome submissions for new custom functions. For information
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on how to submit new custom functions for general distribution, see:
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help contrib
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EXAMPLE
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If calc compiled with ALLOW_CUSTOM= (custom disabled):
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; print custom("sysinfo", "baseb")
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Calc was built with custom functions disabled
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Error 10195
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If calc compiled with ALLOW_CUSTOM= -DCUSTOM and is invoked without -C:
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; print custom("sysinfo", "baseb")
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Calc must be run with a -C argument to use custom function
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Error 10194
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If calc compiled with ALLOW_CUSTOM= -DCUSTOM and is invoked with -C:
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; print custom("sysinfo", "baseb")
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32
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LIMITS
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By default, custom is limited to 100 args.
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LINK LIBRARY
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none
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SEE ALSO
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custom_cal, new_custom, contrib
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## Copyright (C) 1999 Landon Curt Noll
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##
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## Calc is open software; you can redistribute it and/or modify it under
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## the terms of the version 2.1 of the GNU Lesser General Public License
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## as published by the Free Software Foundation.
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##
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## Calc is distributed in the hope that it will be useful, but WITHOUT
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## ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
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## or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General
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## Public License for more details.
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##
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## A copy of version 2.1 of the GNU Lesser General Public License is
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## distributed with calc under the filename COPYING-LGPL. You should have
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## received a copy with calc; if not, write to Free Software Foundation, Inc.
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## 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
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##
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## Under source code control: 1997/03/09 16:33:22
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## File existed as early as: 1997
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##
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## chongo <was here> /\oo/\ http://www.isthe.com/chongo/
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## Share and enjoy! :-) http://www.isthe.com/chongo/tech/comp/calc/
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