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RFE: Replacing os:argv

From: Sean B. Palmer <sean+cwm@infomesh.net>
Date: Mon, 09 Aug 2004 19:17:10 +0100
Message-ID: <4117BFA6.5040603@infomesh.net>
To: public-cwm-bugs@w3.org

Daniel Biddle [+BCC] has come up with an excellent suggestion [1], which
I've augmented marginally with his agreement, as to a replacement for
the os:argv builtin property.

The localname "argv" is a counter-intuitive misnomer anyway given that
the property really means "indexOfArg", but the suggestion is for
os:Argv to be a list of the arguments (since it is a list anyway), and
to instead devise a powerful Lisp-esque builtins module for CWM.

CWM would therefore, instead of generating {"1" os:argv "bar". "2"
os:argv "baz"} using the example in [2], have to generate {os:Argv
rdf:first "bar"; rdf:rest ("2")}.

The N3 to get command line arguments would become, for example:

    (os:Argv "1") list:get ?arg .

There are many benefits. For example, this would also enable one to get
the argument count simply by doing something such as:

    os:Argv list:length ?argc .

Or to get a slice of the argv list using:

    (os:Argv "3" "7") list:slice ?someArgs .

It would also maintain consistency with the majority of programming
language libraries throughout time that make the arguments passed on the
command line available in an array.

The os:argv builtin could become merely sugar for {(os:Argv ?subj)
list:index ?objt}, but I suggest that it be deprecated in favour of an
os:indexOfArg property, or deprecated entirely. The rationale--almost
enough to consider this a bug, not an RFE--is that os:argv is extremely
difficult to learn to use for newcomers to the language, and has no
particular mnemonic for remembering it.

I implemented a list builtins module for CWM called "lexp" ([3], [4])
back in 2002, but you'll probably want to use a module with a different
specification. If one of you (DanC, Sir. timbl, or yosi) were to
document the properties you'd like, and suggest a namespace, I'd be
happy to implement the module--it should be trivial anyway.

As a real world example of how os:Argv would change things, here's a
redrafting of a line from the Trust [5] document. The original:

    "1"!os:argv!os:baseAbsolute^log:uri log:semantics :F.

becomes:

    (os:Argv "1").list:get.os:baseAbsolute^log:uri log:semantics :F .

(don't forget to change the "!" forward traversals to "." if that's
what's been decided upon) which I don't think is too heavy a burden to
bear given the benefits, and I hope you agree!

Many thanks,

[1] http://swhack.com/logs/2004-08-09#T17-20-13
[2] http://www.w3.org/2000/10/swap/os
[3] http://lists.w3.org/Archives/Public/www-archive/2002Mar/0002
[4] lexp.py the module ->
http://lists.w3.org/Archives/Public/www-archive/2002Mar/att-0004/lexp.py
[5] http://www.w3.org/2000/10/swap/doc/Trust

-- 
Sean B. Palmer, http://inamidst.com/
Received on Monday, 9 August 2004 18:17:41 UTC

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