From: Robert Klemme <shortcutter@...>
Date: 2011-04-05T22:39:33+09:00
Subject: Re: Seeking advice

On Tue, Apr 5, 2011 at 3:22 PM, Alex Rothbard <alex323@gmail.com> wrote:
> Hi. I am writing a library that will have the ability to access a server
> by many different "transports" (JSON over HTTP, Thrift, etc). Depending
> on which transport the user chooses, different files and classes will
> need to be loaded.
>
> A complete implementation of a transport requires that three classes
> (such as the 'Grid' class below) be implemented from their respective
> base class. Additionally, if the user wants to use JSON over HTTP, they
> shouldn't need to depend on the thrift gem and vice versa. These
> transport classes are used by other classes within the library, and
> should never be used directly by the user.
>
> What is the best way to allow the user of the library to specify a
> transport at runtime? Could I wrap all my implemented transport classes
> in a module and do something like this?:
>
> def initialize(transport)
>  @t = transport
>  @grid = @t::Grid.new
> end
>
> where "transport" could be "MyProject::Transport::Thrift".
>
> Is this a good idea? Is there a better way?

I'd go for factory pattern.

def initialize(transport)
 @t = transport
 @grid = @t.grid
 @grid = @t.grid.new # alternative
end

All transports must implement the particular set of methods of course.

Kind regards

robert

-- 
remember.guy do |as, often| as.you_can - without end
http://blog.rubybestpractices.com/