From: Mike Stok <mike@...>
Date: 2006-09-11T04:25:32+09:00
Subject: Re: patching strings together to make a variable


On 10-Sep-06, at 1:57 PM, Sy Ali wrote:

> On 9/10/06, Mike Stok <mike@stok.ca> wrote:
>> > Previously, I've been duplicating methods and just renaming a  
>> single
>> > variable.. (just to ensure that method1 works the same as  
>> method2) a
>> > variation of this would be cleaner I think.
>> >
>> > My code is still quite hackish, so it's likely that I'll figure  
>> things
>> > out in some time, and will be able to evolve towards even cleaner
>> > code, perhaps dropping this trick.
>>
>> What are you actually trying to do?  Sometimes stepping back from a
>> particular obstacle can give a fresh point of view which sometimes
>> leads to "nicer" code.
>>
>> Mention of duplicating methods and renaming a single variable hints
>> strongly there may be more ways to skin this cat.
>
> I was just looking for an alternative to the classic if/then/else.
>
> My original method would do this:
>
> def test1
>  puts "#{@something_something}"
> end
>
> def test2
>  puts "#{@something_something_else}"
> end
>
> or maybe I could have done this:
>
> def test(string)
>  if string == "something" then
>    puts "#{@something_something}"
>  elsif string == "something_else" then
>    puts "#{@something_something_else}"
>  end
> end
>
> What if I wanted to expand this a thousand-fold?  I'd have to do this:
>
> def test(string)
>  case string
>    when "something" : puts "#{@something_something}"
>    when "something_else" : puts "#{@something_something_else}"
>    # ... repeated many more times
>  end
> end
>
> But that thousand-line case could be replaced with a one-liner:
>
> def test(string)
>  puts "#{instance_variable_get("@#{string + "_something"}")}"
> end
>
>
> I got here because I was looking at my inelegant code and wanted to
> know how it could be simplified when faced with greater use.
>
> Thinking in infinites.. yes, it's optimising early, but I wanted to
> learn something new.

Depending on what's in your instance variables and how you call test  
you might be able to throw away some punctuation e.g.

   def test(string)
     puts instance_variable_get('@something_' + string)
   end

Mike

-- 

Mike Stok <mike@stok.ca>
http://www.stok.ca/~mike/

The "`Stok' disclaimers" apply.