OOP Design in Delphi using VCL
Pier
lot of code in the main form's unit file. I make use of many of the events
of controls on the main form. I want to make the application more modular so
I thought of deriving classes in separate units for some of the controls on
the main form and overriding methods instead of using events. Is this a good
approach or is there a better way of making the application more modular?
Pier
HAROUCHE, David
Another approach is to use TActionList...
DH...
"Pier" <pi...@ramm.co.za> a écrit dans le message de news:
4794759e$1...@newsgroups.borland.com...
Marc Rohloff [TeamB]
I would only override a control if I wanted to change its
functionality and reuse it. I would break the form up into individual
frames, each handling a group of controls. You can add events and
methods to the frame which your main form can call.
--
Marc Rohloff [TeamB]
marc -at- marc rohloff -dot- com
Peter Morris [CapableObjects]
do all the logic, and then have the various Button.Click events execute
methods on an instance of that class.
Qi
>
> Some suggestions,
>
> 1, Put all controls which on the main form to a separate frame, then put
> that frame on the main form. This gives you the chance to add another
> group of controls without modifying current ones' layout.
>
> 2, Use TActionList instead of events.
>
> 3, By using TActionList, instead of write OnExecute handler for each
> actions, write a handler in TActionList.OnExecute then dispatch the
> event as an ID (use actions' tag property to store the IDs). This is so
> called "command model" in refactoring.
> I heavily use this method in my projects. One public project is the
> LeakInspector in Denomo (Google Denomo for it if you want to see the code).
> This method will significantly reduce the even handlers count. But it's
> not a must so you may skip this point if you don't know how to implement
> it.
>
> 4, Don't do any business/data logic in the even handlers (hey, the
> handlers belong to UI logic). You need some business/data logic, then
> connect them with the UI through some simple interfaces or APIs.
> Your business/data logic module should have the most code instead of the
> UI module.
Sorry for the terrible format (long lines).
I was cheated by ThunderBird that it wrapped the lines virutally
instead of inserting a new line break.
Qi
Some suggestions,
Pier
I created a number of frames, but I find that some event handlers in the
frames do not get called. I have to add events to the frames via the main
form. I want the event handlers in the frame units to be called, since I
have now put the event handlers that were in the main form in their own
frames.
Pier
"Marc Rohloff [TeamB]" <ma...@nospam.marcrohloff.com> wrote in message
news:ij7ivno5...@dlg.marcrohloff.com...
Graeme Geldenhuys
A very nice (and quick) way of minimizing code in Forms is to use the
MGM (Module-GUI-Mediator) design pattern. MGM fits nicely between MVC
(Module-View-Controller) and MVP (Model-View-Presenter), but I think
it's the easiest one to implement and fits very nice with today's modern
GUI frameworks without having to create custom components or register
new components in the component palette. I have used MGM successfully
with 3 GUI toolkits - VCL/CLX, LCL and fpGUI.
I have implemented MGM using RTTI and created generic mediators. This is
a more complex implementation, but a much more simplified implementation
with a couple lines of code is also possible.
For more details on MGM. See the the following:
http://www.atug.com/andypatterns/mgm.htm
My my MGM implementation using RTTI is the tiOPF project on SourceForge.
https://tiopf.svn.sourceforge.net/svnroot/tiopf/tiOPF2/Trunk/GUI
Units of interrest:
tiGenericEditMediators, tiGenericListMediators,
tiGenericTreeviewMediator and tiCompositeMediators
Regards,
- Graeme -
_______________________________________________________
fpGUI - a cross-platform GUI toolkit using Free Pascal
http://opensoft.homeip.net/fpgui/