yes, but why not use delegation:
from the delphi 5 help:
type
IMyInterface = interface
procedure P1;
procedure P2;
end;
TMyImplClass = class
procedure P1;
procedure P2;
end;
TMyClass = class(TInterfacedObject, IMyInterface)
FMyImplClass: TMyImplClass;
property MyImplClass: TMyImplClass read FMyImplClass implements
IMyInterface;
procedure IMyInterface.P1 = MyP1;
procedure MyP1;
end;
procedure TMyImplClass.P1;
...
procedure TMyImplClass.P2;
...
procedure TMyClass.MyP1;
...
var
MyClass: TMyClass;
MyInterface: IMyInterface;
begin
MyClass := TMyClass.Create;
MyClass.FMyImplClass := TMyImplClass.Create;
MyInterface := MyClass;
MyInterface.P1; // calls TMyClass.MyP1;
MyInterface.P2; // calls TImplClass.P2;
end;
is in the object pascal help file, designed for exactly this.....
Nic.
----- Original Message -----
From: "Nahum Wild" <[EMAIL PROTECTED]>
To: "Multiple recipients of list delphi" <[EMAIL PROTECTED]>
Sent: Saturday, September 02, 2000 3:19 PM
Subject: RE: [DUG]: Multiple Inheritance?
> If I understand the dilemma correctly an interface could be used, as per
the
> example code below. They key to it is the implements directive. (look up
> the "implements, interfaces" in the delphi help. Its only available in D4
> inwards though.)
>
> -----------------------------
>
> ISharedCode = interface(IUnknown)
> [GUID]
> function DoSomething : integer;
> end;
>
> TSharedCode = class(TInterfacedObject, ISharedCode)
> public
> function DoSomething : integer;
> end;
>
> TSomeOtherClass = class(TComponent, iSharedCode)
> private
> fSharedCode : ISharedCode;
> public
> constructor Create(AOwner: TComponent); override;
>
> property SharedCode : ISharedCode read fSharedCode impliments
ISharedCode;
>
> end;
>
> function TSharedCode.DoSomething : integer;
> begin
> // does something
> end;
>
> constructor TSomeOtherClass.Create(AOwner: TComponent);
> begin
> inherited Create(AOwner);
>
> fSharedCode := TSharedCode.Create;
> end;
>
> -----------------------------
>
> This means that you can call the following - ASomeOtherClass.DoSomething -
> which calls the appropriate method from the instance of TSharedCode within
> the TSomeOtherClass instance directly without having to have stub methods.
>
> NOTE: This is how I believe it works, I've not had a situation where I've
> had to use it yet. After reading the help I believe that the above code
> should work.
>
>
> Hope that helps.
>
> Nahum Wild
> Game Designer
> Realism Ltd
>
> Pre-Register now for the ESDAO beta test!
> http://www.esdao.net
>
>
> > -----Original Message-----
> > From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]]On
> > Behalf Of Mike Mueller
> > Sent: Saturday, September 02, 2000 14:20
> > To: Multiple recipients of list delphi
> > Subject: RE: [DUG]: Multiple Inheritance?
> >
> >
> > You can't have multiple inheritance in Delphi (or Java). You can in
some
> > types of C++. You *can* have interfaces but that doesn't solve your
> > problem. The reason they don't put it in is because of worry about what
> > happens when ancestor methods 'collide' etc..
> >
> > I suggest creating a TSharedCode in each of your other objects but
rather
> > than put stub/proxy methods in, access the methods via a public
read-only
> > reference to TSharedCode
> >
> > ie.
> >
> > TComponent1 = class (TQuery)
> > private
> > FSharedCode : TSharedCode;
> > public
> > property SharedCode : TSharedCode read FSharedCode;
> > ... (create/destroy it of course)
> >
> > and then call the functions with
> >
> > <some TComponent1Object>.SharedCode.SomeFunction
> >
> > Mike "gonna stick with the SQL kludge" Mueller
> >
> > > -----Original Message-----
> > > From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]]On
> > > Behalf Of Mark Derricutt
> > > Sent: Sunday, 3 September 2000 12:39
> > > To: Multiple recipients of list delphi
> > > Subject: [DUG]: Multiple Inheritance?
> > >
> > >
> > > 'lo, question for the masses...
> > >
> > > I have a group of components that all share a common logic, but
> > due to the
> > > nature of the components, I can't put that common logic in a
> > masterclass,
> > > at the moment I have:
> > >
> > > type
> > > TSharedCode = class(TObject)
> > > TComponent1 = class(TQuery)
> > > TComponent2 = class(TADOQuery)
> > > TComponent3 = class(TSomeMemoryTableComponent)
> > >
> > > TSharedCode has a selection of methods and properties that do the
actual
> > > grunt code, TComponent1/2/3 create an instance of TSharedCode in their
> > > constructor, and have stub/proxy methods defined, so I have:
> > >
> > > procedure TSharedCode.SomeFunction;
> > > begin
> > > // do stuff
> > > end;
> > >
> > > procedure TComponent1.SomeFunction; // this is repeated for
> > each component
> > > begin
> > > SharedObject.SomeFunction;
> > > end;
> > >
> > > This makes for some messy code, having all these little stub
> > functions, so
> > > was wondering if I could use multiple inheritance for this? like:
> > >
> > > type
> > > TComponent1 = class(TQuery, TSharedCode);
> > >
> > > This way, if I add functionality to TSharedCode, its instantly
available
> > > to the other classes without adding new stub functions everywhere.
> > >
> > > If I had windows/delphi here at home I'd prolly load it up and
> > try it, but
> > > alas no.
> > >
> > > Mark
> > >
> > > ------------------------------------------------------------------
> > > ---------
> > > New Zealand Delphi Users group - Delphi List -
[EMAIL PROTECTED]
> > > Website: http://www.delphi.org.nz
> > > To UnSub, send email to: [EMAIL PROTECTED]
> > > with body of "unsubscribe delphi"
> >
> > ------------------------------------------------------------------
> > ---------
> > New Zealand Delphi Users group - Delphi List - [EMAIL PROTECTED]
> > Website: http://www.delphi.org.nz
> > To UnSub, send email to: [EMAIL PROTECTED]
> > with body of "unsubscribe delphi"
> >
> >
>
> --------------------------------------------------------------------------
-
> New Zealand Delphi Users group - Delphi List - [EMAIL PROTECTED]
> Website: http://www.delphi.org.nz
> To UnSub, send email to: [EMAIL PROTECTED]
> with body of "unsubscribe delphi"
>
---------------------------------------------------------------------------
New Zealand Delphi Users group - Delphi List - [EMAIL PROTECTED]
Website: http://www.delphi.org.nz
To UnSub, send email to: [EMAIL PROTECTED]
with body of "unsubscribe delphi"
