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Recognising diferent components...

grebov
grebov asked
on
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Last Modified: 2010-04-04
Suppose that I create next components:
TMyDBEdit (from TDBEdit), TMyDBText (from TDBText), etc.
So, what is the best way to ask is some object is one of my
components (not particulaly one but one of all)? But, without casting, becouse some time I can add some new component and don't want to change casting again and again!
Thanks!
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Commented:
F.e. if you gives both components the same onClickevent:

if Sender is TMyDBEdit then
  TMyDBEdit(Sender).something := somethingelse
else if Sender is TMyDBText then
  TMyDBText(Sender).something := somethingelse

If use use propery's that are in both components (f.e. tag), you can use it without casting.

Floris.



Top Expert 2004

Commented:
hi grebov,

what about

if (Control is TMyDBEdit) then
or
if (Component is TMyDBEdit) then
or
if (Object is TMyDBEdit) then

>is there a way to use there DB properties whithout casting
i guess no

meikl
CERTIFIED EXPERT

Commented:
<<<<<

if Sender is TMyDBEdit then
  TMyDBEdit(Sender).something := somethingelse
else if Sender is TMyDBText then
  TMyDBText(Sender).something := somethingelse

>>>>

This won't work quite as desired, since TMyDBText is inherited from TMyDBEdit. It will pass both tests.

A fix up would be to invert the tests, starting from the outmost class (TMyDBEdit) and then to the parent classes (TDBEdit, TCustomEdit, etc).

Yours,

Alex

Author

Commented:
Edited text of question.

Author

Commented:
Adjusted points to 200

Author

Commented:
Adjusted points to 300

Author

Commented:
None of the comments satisfied me,
so I decided to delete my question
and to ask a new one that is similar.

Author

Commented:
This question has a deletion request Pending

Author

Commented:
I found the answer by myself!
Here it is:
All components must implement the
same interface, for ex: IMyI
and, then, just ask:

for i:=0 to ComponentCount-1 do
if Components[i].GetInterface(IMyI,Temp)
then showmessage(Components[i].Name);

And none of your "experts" didn't
know the answer, so PLEASE
give mi my points BACK!!!

Commented:
This question no longer is pending deletion

Commented:
I object, Simonet and I gave you the anser. Do check what you asked here.

errr, none of the experts didn't know = all experts knew. Do check your logic greboy.

Floris.

Commented:
This one is on us!
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