Object design

Ruby
1

Hi,

Just to make sure, I’d like to know from your as OO programmers if I
did the ‘object thinking’ right.
The idea is the following:

1.- I have different development servers (Unix) where the developers
of various sites have their files to be processed, those files are
application server archives and web server archives, and maybe other
files/archives in the future.
2.- I have a software library server where the software needs to be
placed for processing via certain tool. Ruby is installed on this
server.
3.- When I know the -site name-, I know the source server, source
directory, destination directory, filename and naming convention, and
perhaps more necessary info later.
4.- I have made a list with all this info (I’ve put it in a 2
dimensional array now) related to a certain site
eg. [sitename,
type,src_server,src_dir,dest_dir,appl_archive,web_archive,dest_server]
5.- I need to find out the version number of the last file from a
certain site after copying. Because then I can give the new file the
correct follow-up numer (and some other tweaking)
6.- The same thing applies to the directory on this software library
server, they also have a follow up name according to the date
7.- After this I can call this special tool non-interactively and
import these archives and check if it all worked out.
8.- Sometimes in the request they want to have the web archive and the
application archive to be processed, and sometimes only one of them.

There is a little bit more to this, but those are technicalities which
are not relevant for the object design question I have, or so I think
(some checking, file tweaking, comparing, user switching, ssh and scp
use and so on).

I was thinking at the following objects:

Site object --> where the methods are at least able to serve all
the attribute from this list (see point 3 ). This object is called
with this array (from the list) as an argument

File object --> where methods are able to give the name, change
the file name, changing the permissions of the file name

Directory object --> where methods are able to do the same sort of
things as with the file name. This object can be a parent of the File
object maybe.

SiteList object --> I now have this array just in my front-end code,
but it could better be in an object? However, it is data, and should I
put data in an object? It only changes when a site is added, which
happens two times a year at a maximum.

ThisSpecialTool object --> Do I need to make an object from this
special tool which I use non-interactively?

Some sort of Ruby front-end is initializing the the objects and needs
to be simple, the real code will be in the Site.class.rb,
File.class.rb and Directory.class.rb

Is this the correct way? I hope you can give me some directions if I
am doing things correctly.
How to decide if more objects need to be defined, or some of the
mentioned objects are not necessary at all?

Many thanks for any help, directions, code examples or whatever!
Krekna

2

On Jan 3, 2007, at 9:21 AM, Krekna M. wrote:

2.- I have a software library server where the software needs to be
certain site after copying. Because then I can give the new file the
are not relevant for the object design question I have, or so I think
the file name, changing the permissions of the file name
ThisSpecialTool object --> Do I need to make an object from this

Many thanks for any help, directions, code examples or whatever!
Krekna

Well you already have a File and Directory that will handle what you
need in Ruby. You could probably just add some stuff to them. But
otherwise, it seems reasonable to me.

However, I wonder if you might not need some objects just to marshal
data around. What I see here are mainly data objects with some
operations. That might be enough. But if you find yourself having a
lot of repetition when coding it up, be on the lookout for some sort
of controller object. Something like ServerConnection comes to mind,
but it’ll depend on the details of your implementation.
-Mat

3

On 1/3/07, Krekna M. [email protected] wrote:

File object → where methods are able to give the name, change
the file name, changing the permissions of the file name

Directory object → where methods are able to do the same sort of
things as with the file name. This object can be a parent of the File
object maybe.

Use the ruby classes for this, adding a few things if needed. If you
need more than a few things, you can probably just subclass them, or
use Forwardable to avoid duplicating effort.

SiteList object → I now have this array just in my front-end code,
but it could better be in an object? However, it is data, and should I
put data in an object? It only changes when a site is added, which
happens two times a year at a maximum.

Is your SiteList anything more special than an Array? If it isn’t
there is nothing wrong with an array. If it is, you can preserve
much of your functionality by implementing a meaningful SiteList#each
and including Enumerable

ThisSpecialTool object → Do I need to make an object from this
special tool which I use non-interactively?

Not necessary, but good for organization, future use, and of course,
unit tests.

Some sort of Ruby front-end is initializing the the objects and needs
to be simple, the real code will be in the Site.class.rb,
File.class.rb and Directory.class.rb

site.rb, file.rb, directory.rb

but there is no need for file.rb / diretory.rb unless the ruby classes
are too far from the mark.