From: Charles Oliver Nutter <charles.nutter@...>
Date: 2008-07-01T22:02:53+09:00
Subject: Re: Something like import/package in java?

Christoffer Lern旦 wrote:
> Readability, clear division of responsibilities, ease of development.
> 
> - Even with unit test suites I don't feel secure that the test isn't 
> conditional on files included by other tests.
> - If I want to include all classes from a dir, I have to manually scan 
> through the dir.
> - Clear cut organization of files.
> - Crystal clear dependencies between files.
> - Lots of other small worries I can't quite put my finger on.
> 
> There's some breaking point around 20+ files for me (excluding unit 
> tests), when it becomes really important to have a well-defined 
> organization of my classes, and here just heaping classes into different 
> files doesn't quite cut it for me.

Think of require in terms of "load this file" rather than "import 
everything defined in this file". All require does is an exactly-once 
execution of the file it finds to load, which will in most cases add 
methods, modules, or classes to the global namespace.

To namespace your methods modules and classes, you want to embed them 
within other modules. The typical convention is that your x/y/z dir 
hierarchy will be mirrored in the z.rb file with a nested module X; 
module Y; class Z structure.

Coming from Java, the first thing to remember is that Ruby does not 
impose (or gift, depending on your perspective) a mandatory file path == 
package structure, so you're free (or required) to do namespacing 
however you see fit. If you want a 50-deep dir hierarchy of .rb files to 
all dump stuff into the global namespace, you can do so. But you would 
typically apply your own namespacing for exactly the reasons you 
describe above.

The closest rough equivalent to import would be include, which lets you 
pull in a whole module (as a namespace) into a given module or class 
(thereby making the former module's namespaced constants available 
without full qualification).

- Charlie