From: Robert Klemme <shortcutter@...>
Date: 2008-02-16T21:29:55+09:00
Subject: Re: Code organization and modules

On 16.02.2008 08:48, Brad Ottoson wrote:
> I'm working on an application for generating code skeletons from xml 
> template files and have run into a snag.  I'm trying to organize a set 
> of code in a directory and inside that use modules.  I have a set of 
> files in a subdirectory of my project directory called lang_cpp.  I'll 
> paste in some code to show what I'm trying.
> 
> --method_constructor.rb(in lang_cpp directory):
> 
> module XTECpp::MethodConstructor
>   def getDeclaration(codeClass)
>     return "        " + codeClass.name + "();\n"
>   end
> end
> 
> --method_destructor.rb(in lang_cpp directory):
> module XTECpp::MethodDestructor      
>   def getDeclaration(codeClass)
>     return "        ~" + codeClass.name + "();\n"
>   end
> end
> 
> Later in some other code I include the files using:
> require 'lang_cpp/method_constructor.rb'
> require 'lang_cpp/method_destructor.rb'
> 
> which seems to work fine.  Later on I try the following:
>           case funItem.name
>             when "empty_constructor"
>               headerString << 
> XTECpp::MethodConstructor::getDeclaration(codeClass)
>             when "empty_destructor"
>               headerString << 
> XTECpp::MethodDestructor::getDeclaration(codeClass) 
>             when "operator_equality_assignment"
>               headerString << 
> XTECpp::MethodEqualityAssign::getDeclaration(codeClass)
>             when "readugp"
>               headerString << 
> XTECpp::MethodReadUGP::getDeclaration(codeClass)
>           end
> 
>  and when I run it I get the error:
> 
> C:\code\Ruby\XMLTemplateEngine\lib/lang_cpp/method_constructor.rb:5: 
> uninitialized constant XTECpp (NameError)
>         from C:\code\Ruby\XMLTemplateEngine\lib/lang_cpp.rb:6:in `require'
>         from C:\code\Ruby\XMLTemplateEngine\lib/lang_cpp.rb:6
>         from C:/code/Ruby/XMLTemplateEngine/lib/main.rb:6:in `require'
>         from C:/code/Ruby/XMLTemplateEngine/lib/main.rb:6
> 
> I tried changing the module names to the form XTECpp_MethodConstructor 
> so each function was in it's own unique module but I got errors doing 
> that too.  I'm not sure if you can ever do things this way in Ruby but 
> I'd like to since this organization appeals to me.

You want to use modules as namespaces but actually you define instance 
methods in modules.  A small change will provide what you want:

module XTECpp::MethodConstructor
   def self.getDeclaration(codeClass)
     return "        " + codeClass.name + "();\n"
   end
end

A few other remarks: if you have just one method per module then the 
idea with namespaces does not really make sense.

You use camelCase for method names while in Ruby code this_style is 
conventionally used.

Your methods return leading whitespace which I assume serves to do some 
indentation (and also a trailing linefeed).  I would not do that but let 
the invoking code make sure indentation is properly - otherwise you 
limit yourself to a single level of indentation.  Also modularity of 
your code suffers because now your getXXX methods return a piece of code 
*and* do indentation.

Kind regards

	robert