From: dblack@...
Date: 2002-12-28T00:06:41+09:00
Subject: Re: viral arguments

Hi --

On Fri, 27 Dec 2002, Tom Sawyer wrote:

> thanks for all the response on the float problem. alot of people jumped on
> that one. guess everyone but me knew the answer. :-)
>
> anyway, i'm sitting here coding my billy-bad-ass cgi accounting system, in
> yours truly, ruby, and i'm running into small sticky spots in which i want to
> keep a library i created pure for general use, yet i run into particular
> situations where the behavior needs a minor tweak to work. upon looking at
> these recoccuring catches, i started to develop a notion of "virus-like"
> arguments.
>
> the idea is that rather then pass simple argumments, one could pass a little
> piece of code that would execute in the context of the method.
>
> here's a foo example (vproc is like proc but viral):
>
> 	def foo(x)
> 		i = 1
> 		puts "#{x + i}"
> 	end
>
> 	puts foo(4) --> 5
> 	puts foo(vproc {i + 1}) --> 3
>
> any thoughts? can ruby achieve something like this already?

It's not clear to me why executing "i+1" at the top of the method
would do anything but raise an exception (unless the object has an #i
method)... but in any case, see Kent's answer about blocks.  Also,
consider the impossibility of maintaining and debugging code where the
names of a method's local variables have to be known outside the
method.  That's why they're local :-)


David

-- 
David Alan Black
home: dblack@candle.superlink.net
work: blackdav@shu.edu
Web:  http://pirate.shu.edu/~blackdav