From: darren kirby <bulliver@...>
Date: 2007-06-24T06:28:23+09:00
Subject: Named/positional method args

I have a method here that takes two arguments. Both are optional, with 
appropriate default values. The first is a string which represents a filename 
to write data to. The second is an integer which represents which data from a 
choice of 1 or more should be written to the file. 

So I have:

> def write_picture(outfile = nil, n = 1)

When I call as:

> write_picture()

it does the right thing and uses both defaults.

When I call as:

> write_picture("somefile")

it does the right thing and writes the default data to "somefile"

When I call:

> write_picture("front cover", 1)
> write_picture("back cover", 2)

it does the right thing. However, when I do:

> write_picture(n=1)

I am sure you can guess what happens. I get a picture written to a file 
with "1" as a filename. This seems like non-intuitive behavior. With no 
support for named args shouldn't it error here?

Now: I gather I can do:

> def write_picture(*args)

and perhaps do a type check on each argument, as there must be one each String 
and Integer, and sort them out appropriately. However, this relies too 
heavily, for my comfort, on the users passing sane values to the method.

Is there a clean way to accomplish my goal? Are there plans to give named 
arguments to Ruby in the future? 

Thanks for consideration,
-d
-- 
darren kirby :: Part of the problem since 1976 :: http://badcomputer.org
"...the number of UNIX installations has grown to 10, with more expected..."
- Dennis Ritchie and Ken Thompson, June 1972