invoice object, and so on.
Right now i'm using Delphi's OOP capabilities "just" to create
development objects (controls, componentes, some generic classes, form
inheritance, etc) but not "real world equivalent objects" like persons
and inheriting to create customers, employees, ...
I know it can be done, but from my point of view it could be more a
problem than an improvement on my applications and cronograms
particullary with data bound applications. I'll be comeme reinventing
all what Delphi has gave me (bound controls, datasets, and so on) when
using the "only objects" approach.
I think that the RAD concept relies on OOP for code re-use, component
creation and VCL expansion more than for "real world databound objects"
dessign.
And that a mix of an OOP language but not a completely OOP application's

dessign fits better.
Am i wrong? bye

--
Guillermo Casta?o Acevedo
Gerente de Sistemas - Grupo Millennium Ltda
Guiller...@GrupoMillennium.com
http://www.GrupoMillennium.com

We OO 'purists' do not make work for ourselves, just for the fun of it; we
have found out the advantages of good design, reusability, encapsulation,
etc. and, although we take a lot of time up front to put the various layers
(OPF, MVP) in place, we then start to save time and effort.

Several solutions to using data-aware controls with business objects do
exist; they are good at what they do, but are, of necessity a best fit
solution rather than the ideal.

I am working on a generic MVP framework that will provide an alternative to
the TDataset mentality. It is not an easy thing, because Delphi tends to
lead you into RAD before you get to learn how to do quality.

I have consulted on several projects, and the ones that adopt an OO
approach, take longer to get the initial release in place, then they start
saving a *lot* of time and effort.

Joanna

Joanna, you talk about OPF and MVP. What is this?
Thanks
Udo

Joanna

           regarding your MVP framework that you posted. There would
 seem to be a bug in the way it handles commands.

In the demo provided if you select a string(any but top one), and then
select "move up", from the context menu.

Then instead of clicking on another entry you select the context menu
again, do this until entry is the top one. When you select the context
menu this time, instead of the "move up" menu being disabled it is
enabled. If you now select it the top string disapears!

David Fisher

Thanks,

Terrence Koehn
Orion Law Management System

I will look at it, but see if you can work out how to fix it, this will help
you to understand how it all works.

Joanna

Joanna

I have a final question: in your experience, how much time the OOP approach
saves on future version compared with the initial efforce and compared with the
same process on the hybrid model? Does the initial efforce can be reduced in
future projects?

Thanks a lot for your valuable point of view and experience. bye
--
Guillermo Casta?o Acevedo
Gerente de Sistemas - Grupo Millennium Ltda
Guiller...@GrupoMillennium.com
http://www.GrupoMillennium.com

1. Regardless of future projects, the *current* project will benefit greatly
from a well designed framework. You should see far fewer bugs related to the
overall architecture and changes / enhancements will be much easier to
implement.

2. The framework is what is reusable in its entirety, it will not have to be
developed again (though may continue to be enhanced). Interfaces and classes
such as IListModel/TListModel, ISubject/TSubject, as Joanna describes,
implement a lot of common functionality that can be reused in every future
project.

So in short, it takes a lot more thought initially to implement and learn to
use such a framework, but it will save a great deal of time and help produce
much better quality apps for every subsequent project. You *must* include
the savings in bug-fixing and maintenance that comes *after* development as
well as the savings in development itself.

--
Wayne Niddery (Logic Fundamentals, Inc.)
RADBooks: http://www.logicfundamentals.com/RADBooks/delphibooks.html
Those who disdain wealth as a worthy goal for an individual or a society
seem not to realize that wealth is the only thing that can prevent
poverty. - Thomas Sowell

As both Joanna and Wayne have pointed out, there are up-front costs for OO
analysis and design that you have to be willing to pay. OO is a lot like
computation itself: if a notepad meets your needs, then don't bother writing
a speadsheet.

That being the case, you have to be honest about what you might want to fix
about your current approach, and honest about what it's worth to you to fix
it. There will be a lot of late nights when you have to remind yourself of
those goals. Initially, anyway<g>.

bobD

The kind of interfaces and classes Joanna presents are useful (reusable) in
virtually any application. Specific implementations of Domain classes may or
may not find reuse in subsequent applications.

I also find practically every project I do is vastly different and/or for
different clients. As a result there are many classes I develop that will
never see reuse in future apps. That does not lessen their value and benefit
in the current app. So the answer is yes, OOD is very much applicable to
real-world objects. These real-world objects will be Model objects in
Joanna's framework. E.g. you could create a descendant of the TListModel
that holds TPerson or TAccount objects and create other classes as she
describes to present  and update these objects. IOW, if you do not design
such Domain classes then you will not be able to take advantage of a such a
framework.

It may *seem* unproductive to take a lot more time up front to design all
these domain classes and creating diagrams to describe the relationships
between the classes, but you will end up spending a lot less time in the
actual development phase and even less time bug-fixing later. At worse case
you usually break even on when a project is delivered, but you deliver a
much better app. Even if it takes longer, you will still save time and money
in the long run because of better design and better quality.

--
Wayne Niddery (Logic Fundamentals, Inc.)
RADBooks: http://www.logicfundamentals.com/RADBooks/delphibooks.html
Those who disdain wealth as a worthy goal for an individual or a society
seem not to realize that wealth is the only thing that can prevent
poverty. - Thomas Sowell

Cheers,
Jim Cooper

_____________________________________________

Jim Cooper      jcoo...@tabdee.ltd.uk
Tabdee Ltd      http://www.tabdee.ltd.uk

TurboSync - Writing Palm conduits with Delphi
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