From: Paul van Delst <Paul.vanDelst@...>
Date: 2007-01-09T00:55:10+09:00
Subject: code organisation help request

Hello,

I've written some ruby code that creates Fortran95 code to define and manipulate derived 
types (aka structures) as well as perform "regular" (what I ambiguously refer to as 
"Binary") and netCDF I/O. Via a driver script, I provide a text file with the simple 
structure definition to my ruby code and out pops three modules (fortran95 modules, not 
ruby ones) that I can compile.

The way I do this currently is like so:

f=FDefMod.new
f.read(def_file)     # Parse the file containing an f95 structure definition
f.createDefModule    # Create the structure definition f95 module
f.createBinIOModule  # Create the binary I/O f95 module
f.createNCIOModule   # Create the netCDF I/O f95 module

This creates three compilable f95 modules. (It's all very cool, really :o)

The problem I'm facing is that my ruby class definition file, fdefmod.rb, has grown 
unmanageably large and I want to split the code up into more manageable pieces but I can't 
figure out how best to do it.

I would like all the methods used to create the f95 definition code (i.e. the public 
createDefModule and about 20 private methods) to reside in one file, the methods to create 
the f95 binary I/O in another, and similarly for the methods to create the f95 netCDF I/O 
code. E.g.

   fdefmod.rb      : contains the FDefMod class definition and associated methods
   fdefmod_def.rb  : contains the instance methods that create the f95 structure
                       definition module
   fdefmod_binio.rb: contains the instance methods that create the f95 binary I/O module
   fdefmod_ncio.rb : contains the instance methods that create the f95 netCDF I/O module

The last three files would be included (in the C sense) in the FDefMod class definition 
file. All of the methods in the three "functional categories" (def, binio, and ncio) are, 
of course, instance methods. Currently, the monolithic fdefmod.rb file contains everything 
and it's a nightmare to organise the code itself and associated unit tests -- to say 
nothing of adding new features.

So: how to split up the code? Module mixins? Subclasses?

The way I see it, the above type of organisational structure, while logical, is opposite 
to how one would typically use modules to mixin methods since the methods in question 
aren't generic, they're very specific.

And inheritance doesn't seem right either since each code component I'm trying to separate 
aren't really classes in their own right; they're just a bunch of methods operating on a 
class to create a particular format of output.

In addition, there are a number of class methods that are used by all three "functional 
categories" of code. These class methods are just little utilities for formatting the 
output f95 code are all private to the FDefMod class.

I've been thinking myself in circles for a while now, so my explanation may be malformed. 
If so, I apologise.

Any ideas, suggestions, hints, etc much appreciated.

cheers,

paulv

-- 
Paul van Delst             Ride lots.
CIMSS @ NOAA/NCEP/EMC               Eddy Merckx