From: Richard Kilmer <rich@...>
Date: 2004-06-17T12:53:08+09:00
Subject: Re: [OT] RE: require vs require_gem




On 6/16/04 11:46 PM, "Sean O'Dell" <sean@celsoft.com> wrote:

>> What you describe doesn't quite follow the Ruby 'require' process.
>> 'require' isn't the same as #include of java's import: you do not need
>> to require a library from every file that uses it. Once you have
>> require'd a file everything in it has already been brought in to the
>> interpreter.
>> 
>> For an app/lib type of work you describe, where users will always call
>> through the "base file", you can just put all your requires there (or in
>> one file called from the base). This has the advantage that you can deal
>> with all external libraries and their versions in one place.
> 
> I find it's better to spread out the requires (not too liberally), so you only
> load libraries when they're really needed.  Sometimes a program won't use
> some of the "require" files, so it's possible to avoid unnecessary loading of
> libraries it won't use.
> 

I second that, and actually put some 'require' statements in methods right
before I use them.  That way if a method is called, the library is loaded,
otherwise not:

  def load_from_yaml(filename)
    require 'yaml'
    YAML.load(File.read(filename))
  end

So if this method is called, yaml is loaded (if necessary), otherwise its
not.

-rich