From: Just Another Victim of the Ambient Morality <ihatespam@...>
Date: 2007-12-09T09:55:04+09:00
Subject: How much would variable declarations in Ruby make you wince?

    So, I had a conversation with a colleague of mine and he brought up a 
feature request for another language that is a lot like Ruby but is not 
Ruby.  It was an interesting request and, after I had thought about it a 
bit, I discovered that I would like this feature, too!

    The two most popular sources of bugs for me when programming in Ruby 
are:

1)  Passing the wrong object as a parameter to a method.
2)  Accidentally creating a new variable.

    Unfortunately for me, very little can be done about my first point.  I 
understand and enjoy the power of duck-typing, which specifically allows me 
to exercise this bug.
    However, something can be done about the second point.  Let me exemplify 
the problem:


list = create_useful_list

if should_modify_list(list)
    # I meant to modify the variable "list" here...
    liist = modify_list(list)
end

use_list(list)


    ...obviously, this is a seriously contrived example but it should 
clarify my point.  I so amazingly meant to assign to the pre-existing 
variable "list" but I accidentally created a new variable.  It's not even 
typos with me.  I often thought I named a variable something descriptive 
when I actually named it something else equally descriptive.  This can be a 
surprisingly annoying bug to track...
    A solution to my problem would be to require variable declarations. 
Something like the "my" keyword of a strict PERL script.  Ruby would 
probably not use "my," despite its PERL roots.  Maybe "var?"


var list = create_useful_list

if should_modify_list(list)
    # A compile time error will occur here...
    # ...after 1.9 is released...
    liist = modify_list(list)
end

use_list(list)


    What do you all think?
    Thank you...