From: Martin Man <Martin.Man@...>
Date: 2002-02-15T08:09:15+09:00
Subject: Keyword arguments (Was: File.open weirdness)


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On Fri, Feb 15, 2002 at 04:59:23AM +0900, Craig Files wrote:
> "David Alan Black" <dblack@candle.superlink.net> wrote:
> >=20
> > Put the permissions after the mode :-)
> >=20
> Thanks, this is contrary to the information in the "Programming Ruby"
> book, where the example for File.new shows the permissions before the
> mode.
>=20

hi all,
	sorry to bother you once again with keyword arguments, but previous
example with File.open clearly shows the need for change. I've searched the
archves and checked TODO in ruby's cvs repository and found
two syntax proposals.

func(:arg1 =3D xx, :arg2 =3D yy)
func(arg1: xx, arg2: yy)

I like the second one more because it's less verbose, but

IMHO (after having worked with Objective-C in the past) the above problem w=
ith
File.open et al, can not be solved by using keyword arguments as proposed
above.

Assuming the arguments of a function must be named,=20
e.g. the symbol for respective argument of a function must always be present

File.open (name: "xxx", mode: 0yyy)

and the old-C-style syntax=20

File.open ("xxx", 0yyy)

is forbidden (just hypothesis), we surely gain a lot, cause these stupid and
time-consuming mistakes like the one above can't happen anymore, because we
force the developer to name the arguments, but at the same time we make a
develper completely confused because he/she still must remember what the ar=
gs
for a function are (because they still can be swapped), e.g.

File.open (mode: 0yyy, name: "xxx")

And now see the beauty of smalltalk's position-fixed-named-arguments syntax
(something that even lisp doesn't have)

[File open: "xxx" withMode: 0yyy]

The general syntax here (that you all obviously know :-))) is

[receiver message: arg1 withArg: arg2 anotherArg: arg3 andYetAnother: arg4]

to compare, in ruby we have

receier.message (arg1, withArg: arg2, andYetAnother: arg4, anotherArg: arg3)

another hypothetical example with GUI

MessageBox.question ("Quit ?", windowTitle: "Are you sure...?")

compared to

[MessageBox question: "Are you sure...?" windowTitle: "Quit ?"]

=2E..what do you think guys about all that stuff, looking forward to hear s=
ome
objections... :)

thanx for reading so far, and
thanx for cool programming language :-)

martin
--=20
1024D/6E060223    2CC0 4AF6 92DA 5CBF 5F09  7BCB 6202 7024 6E06 0223
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