Re: Good design
thanks Dan and Scott for improving my design .
in my case:- I am using this to send a message from a subclased control
to another subclassed control i.e,
View->listctrl1->tabctrl->dialog->listcontrol2.SendMessage(...)
which is ugly.
As you said
"The parent should simply call its child with information and let the
child
implementation be responsible for figuring out what to do with it."
Now using GetParent()->SendMessage I m concerned of
1.Parameters in sendMessage-
2.how will the child control will know it received a notification from
the parent. (Ofcourse through OnMessage)
Are we passing parameters specifically related to that control that
will get notified.
I worked yesterday but the other control does not get notifiaction.
void CMyListCtrlOne::OnNMClick(NMHDR *pNMHDR, LRESULT *pResult)
{
// TODO: Add your control notification handler code here
*pResult = 0;
GetParent()->SendMessage(WM_INSERT_ITEMS,0,0);//This message is
registered in teh second class list control using ON_MESSAGE
}
I look forward in further improving my code and standards from you
guys.
thanks
Tom
Dan Bloomquist wrote:
Scott McPhillips [MVP] wrote:
The goal of "good" design is not ease of communication, it is to reduce
inter-dependencies, so that the app can evolve without having to make
widespread changes. This improves maintainability, which is typically
the largest cost element in a program's life cycle.
Well said. And once the discipline is in place, I think the ease of
communication follows.
for nicetom786@yahoo.com:
Get to know:
TN062: Message Reflection for Windows Controls
And here is what scott is getting at. Say you start building a list
control that handles item(s) drag and drops. You need to let your parent
know what is going on. You do a pMyParent->Member( ). Now you are stuck,
your code is no good anywhere else. You have to duplicate it every time
you want to use it. Or it means your parent is derived from an
intermediate class that has such a members. Your app evolves to where
you have a dozen list controls that support drag and drop. Later you
want to start a new project, the same goes.
You could instead just drop your super duper control in, set the
properties that apply in one line, let it move to a dll some day, and
only handle the messages that you need. Your new super duper control can
almost work in a vacuum, all by it self without the need of a superclass.
It can handle the drag and drop all by itself because the parent doesn't
need to know until destruction, or the parent can know, or the parent
can say no by setting *pResult= 1; And you only had to write it once and
for all.
Best, Dan.
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