Need help: about OOP inheritance/abstract class

[Tee]

Hi,

I have a base usercontrol with a method (blank method, no code), I have
another few usercontrols that will inherit this base usercontrol, but I want
to force all the usercontrol that inheriting this base usercontrol to
override the method with its own code. How do I do it?

I have tried to make the base usercontrol an abstract class (mustinherits +
mustoverrides), this works, but all the usercontrols that inherit it will
not able to open in VS designer because of inherting an abstract class.

I have also tried to use interface, this works as well, but I can't force
those usercontrols that inherit base usercontrol MUST have the interface.

Anyone has a solution for this?


Thanks,
Tee

[Elementary Penguin]

Re: Need help: about OOP inheritance/abstract class

Tee wrote:
[color=blue]
> Hi,
>
> I have a base usercontrol with a method (blank method, no code), I have
> another few usercontrols that will inherit this base usercontrol, but I
> want to force all the usercontrol that inheriting this base usercontrol to
> override the method with its own code. How do I do it?[/color]

If you are going to /force/ them to override it ( polymorphism ) why have it
in the first place?

You should define an *interface* with a stub method and force them to
implement it.

I do this in one of my web service applications. There are two interfaces
and a base abstract class. The interface accounts for methods that must
be implemented in the derived classes, but which have no default method in
the abstract class. So each derived class has one abstract class and two
interfaces to inherit from.


--

http://texeme.com

Textcasting Technology
Incognito Blog

http://incognito.texeme.com

[Elementary Penguin]

Re: Need help: about OOP inheritance/abstract class

Tee wrote:
[color=blue]
> Hi,
>
> I have a base usercontrol with a method (blank method, no code), I have
> another few usercontrols that will inherit this base usercontrol, but I
> want to force all the usercontrol that inheriting this base usercontrol to
> override the method with its own code. How do I do it?[/color]

If you are going to /force/ them to override it ( polymorphism ) why have it
in the first place?

You should define an *interface* with a stub method and force them to
implement it.

I do this in one of my web service applications. There are two interfaces
and a base abstract class. The interface accounts for methods that must
be implemented in the derived classes, but which have no default method in
the abstract class. So each derived class has one abstract class and two
interfaces to inherit from.


--

http://texeme.com

Textcasting Technology
Incognito Blog

http://incognito.texeme.com

[Olorin]

Re: Need help: about OOP inheritance/abstract class

I haven't tried, but have you tried to use inheirtance AND interface
together?

i.e.
* base class with stuff that should be inherited as-is
* interface with the definition of the method that the inheriting
classes should implement/override
* inheriting/implementing classes: they inherit from the base class,
AND they implement the interface.

The children should then get all that the base class provides and Be
Forced to implement the method(s) defined in the interface.
HTH,
F.O.R.

[Olorin]

Re: Need help: about OOP inheritance/abstract class

I haven't tried, but have you tried to use inheirtance AND interface
together?

i.e.
* base class with stuff that should be inherited as-is
* interface with the definition of the method that the inheriting
classes should implement/override
* inheriting/implementing classes: they inherit from the base class,
AND they implement the interface.

The children should then get all that the base class provides and Be
Forced to implement the method(s) defined in the interface.
HTH,
F.O.R.

[Tee]

Re: Need help: about OOP inheritance/abstract class

I have tried it.
[color=blue]
> The children should then get all that the base class provides and Be
> Forced to implement the method(s) defined in the interface.
> HTH,
> F.O.R.[/color]

The base class that implements the interface will automatically has the
method in the class (just an empty method, no code).
And yes, the children get all the base class provided, and they inherit the
empty method as well ... the problem is it won't force the children to
overrides it.


Thanks.


"Olorin" <francesco.rizz i@gmail.com> wrote in message
news:1106795597 .572258.201360@ c13g2000cwb.goo glegroups.com.. .[color=blue]
> I haven't tried, but have you tried to use inheirtance AND interface
> together?
>
> i.e.
> * base class with stuff that should be inherited as-is
> * interface with the definition of the method that the inheriting
> classes should implement/override
> * inheriting/implementing classes: they inherit from the base class,
> AND they implement the interface.
>
> The children should then get all that the base class provides and Be
> Forced to implement the method(s) defined in the interface.
> HTH,
> F.O.R.
>[/color]

[Tee]

Re: Need help: about OOP inheritance/abstract class

I have tried it.
[color=blue]
> The children should then get all that the base class provides and Be
> Forced to implement the method(s) defined in the interface.
> HTH,
> F.O.R.[/color]

The base class that implements the interface will automatically has the
method in the class (just an empty method, no code).
And yes, the children get all the base class provided, and they inherit the
empty method as well ... the problem is it won't force the children to
overrides it.


Thanks.


"Olorin" <francesco.rizz i@gmail.com> wrote in message
news:1106795597 .572258.201360@ c13g2000cwb.goo glegroups.com.. .[color=blue]
> I haven't tried, but have you tried to use inheirtance AND interface
> together?
>
> i.e.
> * base class with stuff that should be inherited as-is
> * interface with the definition of the method that the inheriting
> classes should implement/override
> * inheriting/implementing classes: they inherit from the base class,
> AND they implement the interface.
>
> The children should then get all that the base class provides and Be
> Forced to implement the method(s) defined in the interface.
> HTH,
> F.O.R.
>[/color]

[Bruce Wood]

Re: Need help: about OOP inheritance/abstract class

This is not just a problem with user controls; it is also a problem
with inheriting Forms.

You cannot use an abstract base class for the reasons you mentioned.
There is no way around it at present.

The best you can do is write the methods in the base class to throw a
NotImplementedE xception. Then if the child class does not override them
it will blow up at run time. There is no way to enforce the override
via a compile-time check.

[Bruce Wood]

Re: Need help: about OOP inheritance/abstract class

This is not just a problem with user controls; it is also a problem
with inheriting Forms.

You cannot use an abstract base class for the reasons you mentioned.
There is no way around it at present.

The best you can do is write the methods in the base class to throw a
NotImplementedE xception. Then if the child class does not override them
it will blow up at run time. There is no way to enforce the override
via a compile-time check.

[Dennis Myrén]

Re: Need help: about OOP inheritance/abstract class

Why not just(shortened) :

abstract class Abstract
{
public abstract void MustOverrideThi sAbstractMethod ( ) ;
}

class Concrete : Abstract
{
override public void MustOverrideThi sAbstractMethod ( )
{
//Implement something here.
}

}

Declaring a method as abstract within an abstract class means the base class
will demand an implementation of that method from the concrete derived
class.


--
Regards,
Dennis JD Myrén
Oslo Kodebureau
"Tee" <thy@streamyx.c om> wrote in message
news:unWQZ0BBFH A.380@TK2MSFTNG P10.phx.gbl...[color=blue]
> Hi,
>
> I have a base usercontrol with a method (blank method, no code), I have
> another few usercontrols that will inherit this base usercontrol, but I
> want
> to force all the usercontrol that inheriting this base usercontrol to
> override the method with its own code. How do I do it?
>
> I have tried to make the base usercontrol an abstract class (mustinherits
> +
> mustoverrides), this works, but all the usercontrols that inherit it will
> not able to open in VS designer because of inherting an abstract class.
>
> I have also tried to use interface, this works as well, but I can't force
> those usercontrols that inherit base usercontrol MUST have the interface.
>
> Anyone has a solution for this?
>
>
> Thanks,
> Tee
>
>[/color]

[Dennis Myrén]

Re: Need help: about OOP inheritance/abstract class

Why not just(shortened) :

abstract class Abstract
{
public abstract void MustOverrideThi sAbstractMethod ( ) ;
}

class Concrete : Abstract
{
override public void MustOverrideThi sAbstractMethod ( )
{
//Implement something here.
}

}

Declaring a method as abstract within an abstract class means the base class
will demand an implementation of that method from the concrete derived
class.


--
Regards,
Dennis JD Myrén
Oslo Kodebureau
"Tee" <thy@streamyx.c om> wrote in message
news:unWQZ0BBFH A.380@TK2MSFTNG P10.phx.gbl...[color=blue]
> Hi,
>
> I have a base usercontrol with a method (blank method, no code), I have
> another few usercontrols that will inherit this base usercontrol, but I
> want
> to force all the usercontrol that inheriting this base usercontrol to
> override the method with its own code. How do I do it?
>
> I have tried to make the base usercontrol an abstract class (mustinherits
> +
> mustoverrides), this works, but all the usercontrols that inherit it will
> not able to open in VS designer because of inherting an abstract class.
>
> I have also tried to use interface, this works as well, but I can't force
> those usercontrols that inherit base usercontrol MUST have the interface.
>
> Anyone has a solution for this?
>
>
> Thanks,
> Tee
>
>[/color]

[Tee]

Re: Need help: about OOP inheritance/abstract class

Hi Dennis,

See my previous post:[color=blue]
>I have tried to make the base usercontrol an abstract class (mustinherits +[/color]
mustoverrides), this works, but all the usercontrols that inherit it will
not able to open in VS designer because of inherting an abstract class.

This just won't work on forms or usercontrols ... it won't effect runtime,
but it's trouble enough if you can't open it in VS Designer.


Thanks,
Tee


"Dennis Myrén" <dennis@oslokb. no> wrote in message
news:dN1Kd.6183 $Sl3.148441@new s4.e.nsc.no...[color=blue]
> Why not just(shortened) :
>
> abstract class Abstract
> {
> public abstract void MustOverrideThi sAbstractMethod ( ) ;
> }
>
> class Concrete : Abstract
> {
> override public void MustOverrideThi sAbstractMethod ( )
> {
> //Implement something here.
> }
>
> }
>
> Declaring a method as abstract within an abstract class means the base[/color]
class[color=blue]
> will demand an implementation of that method from the concrete derived
> class.
>
>
> --
> Regards,
> Dennis JD Myrén
> Oslo Kodebureau
> "Tee" <thy@streamyx.c om> wrote in message
> news:unWQZ0BBFH A.380@TK2MSFTNG P10.phx.gbl...[color=green]
> > Hi,
> >
> > I have a base usercontrol with a method (blank method, no code), I have
> > another few usercontrols that will inherit this base usercontrol, but I
> > want
> > to force all the usercontrol that inheriting this base usercontrol to
> > override the method with its own code. How do I do it?
> >
> > I have tried to make the base usercontrol an abstract class[/color][/color]
(mustinherits[color=blue][color=green]
> > +
> > mustoverrides), this works, but all the usercontrols that inherit it[/color][/color]
will[color=blue][color=green]
> > not able to open in VS designer because of inherting an abstract class.
> >
> > I have also tried to use interface, this works as well, but I can't[/color][/color]
force[color=blue][color=green]
> > those usercontrols that inherit base usercontrol MUST have the[/color][/color]
interface.[color=blue][color=green]
> >
> > Anyone has a solution for this?
> >
> >
> > Thanks,
> > Tee
> >
> >[/color]
>
>[/color]

[Tee]

Re: Need help: about OOP inheritance/abstract class

Hi Dennis,

See my previous post:[color=blue]
>I have tried to make the base usercontrol an abstract class (mustinherits +[/color]
mustoverrides), this works, but all the usercontrols that inherit it will
not able to open in VS designer because of inherting an abstract class.

This just won't work on forms or usercontrols ... it won't effect runtime,
but it's trouble enough if you can't open it in VS Designer.


Thanks,
Tee


"Dennis Myrén" <dennis@oslokb. no> wrote in message
news:dN1Kd.6183 $Sl3.148441@new s4.e.nsc.no...[color=blue]
> Why not just(shortened) :
>
> abstract class Abstract
> {
> public abstract void MustOverrideThi sAbstractMethod ( ) ;
> }
>
> class Concrete : Abstract
> {
> override public void MustOverrideThi sAbstractMethod ( )
> {
> //Implement something here.
> }
>
> }
>
> Declaring a method as abstract within an abstract class means the base[/color]
class[color=blue]
> will demand an implementation of that method from the concrete derived
> class.
>
>
> --
> Regards,
> Dennis JD Myrén
> Oslo Kodebureau
> "Tee" <thy@streamyx.c om> wrote in message
> news:unWQZ0BBFH A.380@TK2MSFTNG P10.phx.gbl...[color=green]
> > Hi,
> >
> > I have a base usercontrol with a method (blank method, no code), I have
> > another few usercontrols that will inherit this base usercontrol, but I
> > want
> > to force all the usercontrol that inheriting this base usercontrol to
> > override the method with its own code. How do I do it?
> >
> > I have tried to make the base usercontrol an abstract class[/color][/color]
(mustinherits[color=blue][color=green]
> > +
> > mustoverrides), this works, but all the usercontrols that inherit it[/color][/color]
will[color=blue][color=green]
> > not able to open in VS designer because of inherting an abstract class.
> >
> > I have also tried to use interface, this works as well, but I can't[/color][/color]
force[color=blue][color=green]
> > those usercontrols that inherit base usercontrol MUST have the[/color][/color]
interface.[color=blue][color=green]
> >
> > Anyone has a solution for this?
> >
> >
> > Thanks,
> > Tee
> >
> >[/color]
>
>[/color]

[Dennis Myrén]

Re: Need help: about OOP inheritance/abstract class

Sorry, i should probably read the posts fully before replying them.

I had a bunch of webforms once which all needed common extra features in
order
to provide the functionality of a step in a wizard.
There was no way i could force those webforms to implement my custom
interface
in addition to inherit System.Web.UI.P age.
But i myself though, knew which ones of them should provide that
functionality,
and had them implement that interface.
class WizardStep1 : System.Web.UI.P age, IWizardStep



--
Regards,
Dennis JD Myrén
Oslo Kodebureau
"Tee" <thy@streamyx.c om> wrote in message
news:%23K7ha9EB FHA.2624@TK2MSF TNGP11.phx.gbl. ..[color=blue]
> Hi Dennis,
>
> See my previous post:[color=green]
>>I have tried to make the base usercontrol an abstract class (mustinherits
>>+[/color]
> mustoverrides), this works, but all the usercontrols that inherit it will
> not able to open in VS designer because of inherting an abstract class.
>
> This just won't work on forms or usercontrols ... it won't effect runtime,
> but it's trouble enough if you can't open it in VS Designer.
>
>
> Thanks,
> Tee
>
>
> "Dennis Myrén" <dennis@oslokb. no> wrote in message
> news:dN1Kd.6183 $Sl3.148441@new s4.e.nsc.no...[color=green]
>> Why not just(shortened) :
>>
>> abstract class Abstract
>> {
>> public abstract void MustOverrideThi sAbstractMethod ( ) ;
>> }
>>
>> class Concrete : Abstract
>> {
>> override public void MustOverrideThi sAbstractMethod ( )
>> {
>> //Implement something here.
>> }
>>
>> }
>>
>> Declaring a method as abstract within an abstract class means the base[/color]
> class[color=green]
>> will demand an implementation of that method from the concrete derived
>> class.
>>
>>
>> --
>> Regards,
>> Dennis JD Myrén
>> Oslo Kodebureau
>> "Tee" <thy@streamyx.c om> wrote in message
>> news:unWQZ0BBFH A.380@TK2MSFTNG P10.phx.gbl...[color=darkred]
>> > Hi,
>> >
>> > I have a base usercontrol with a method (blank method, no code), I have
>> > another few usercontrols that will inherit this base usercontrol, but I
>> > want
>> > to force all the usercontrol that inheriting this base usercontrol to
>> > override the method with its own code. How do I do it?
>> >
>> > I have tried to make the base usercontrol an abstract class[/color][/color]
> (mustinherits[color=green][color=darkred]
>> > +
>> > mustoverrides), this works, but all the usercontrols that inherit it[/color][/color]
> will[color=green][color=darkred]
>> > not able to open in VS designer because of inherting an abstract class.
>> >
>> > I have also tried to use interface, this works as well, but I can't[/color][/color]
> force[color=green][color=darkred]
>> > those usercontrols that inherit base usercontrol MUST have the[/color][/color]
> interface.[color=green][color=darkred]
>> >
>> > Anyone has a solution for this?
>> >
>> >
>> > Thanks,
>> > Tee
>> >
>> >[/color]
>>
>>[/color]
>
>[/color]

[Dennis Myrén]

Re: Need help: about OOP inheritance/abstract class

Sorry, i should probably read the posts fully before replying them.

I had a bunch of webforms once which all needed common extra features in
order
to provide the functionality of a step in a wizard.
There was no way i could force those webforms to implement my custom
interface
in addition to inherit System.Web.UI.P age.
But i myself though, knew which ones of them should provide that
functionality,
and had them implement that interface.
class WizardStep1 : System.Web.UI.P age, IWizardStep



--
Regards,
Dennis JD Myrén
Oslo Kodebureau
"Tee" <thy@streamyx.c om> wrote in message
news:%23K7ha9EB FHA.2624@TK2MSF TNGP11.phx.gbl. ..[color=blue]
> Hi Dennis,
>
> See my previous post:[color=green]
>>I have tried to make the base usercontrol an abstract class (mustinherits
>>+[/color]
> mustoverrides), this works, but all the usercontrols that inherit it will
> not able to open in VS designer because of inherting an abstract class.
>
> This just won't work on forms or usercontrols ... it won't effect runtime,
> but it's trouble enough if you can't open it in VS Designer.
>
>
> Thanks,
> Tee
>
>
> "Dennis Myrén" <dennis@oslokb. no> wrote in message
> news:dN1Kd.6183 $Sl3.148441@new s4.e.nsc.no...[color=green]
>> Why not just(shortened) :
>>
>> abstract class Abstract
>> {
>> public abstract void MustOverrideThi sAbstractMethod ( ) ;
>> }
>>
>> class Concrete : Abstract
>> {
>> override public void MustOverrideThi sAbstractMethod ( )
>> {
>> //Implement something here.
>> }
>>
>> }
>>
>> Declaring a method as abstract within an abstract class means the base[/color]
> class[color=green]
>> will demand an implementation of that method from the concrete derived
>> class.
>>
>>
>> --
>> Regards,
>> Dennis JD Myrén
>> Oslo Kodebureau
>> "Tee" <thy@streamyx.c om> wrote in message
>> news:unWQZ0BBFH A.380@TK2MSFTNG P10.phx.gbl...[color=darkred]
>> > Hi,
>> >
>> > I have a base usercontrol with a method (blank method, no code), I have
>> > another few usercontrols that will inherit this base usercontrol, but I
>> > want
>> > to force all the usercontrol that inheriting this base usercontrol to
>> > override the method with its own code. How do I do it?
>> >
>> > I have tried to make the base usercontrol an abstract class[/color][/color]
> (mustinherits[color=green][color=darkred]
>> > +
>> > mustoverrides), this works, but all the usercontrols that inherit it[/color][/color]
> will[color=green][color=darkred]
>> > not able to open in VS designer because of inherting an abstract class.
>> >
>> > I have also tried to use interface, this works as well, but I can't[/color][/color]
> force[color=green][color=darkred]
>> > those usercontrols that inherit base usercontrol MUST have the[/color][/color]
> interface.[color=green][color=darkred]
>> >
>> > Anyone has a solution for this?
>> >
>> >
>> > Thanks,
>> > Tee
>> >
>> >[/color]
>>
>>[/color]
>
>[/color]