Hello,

I have a group of custom controls and each control is derived from a
base class that performs some standard operations and enforces an
interface by having some abstract methods. Ideally, I don't want my
base class visible outside the assembly; also no instantiation, and no
access by nonderived types. Since C# does not allow multiple
inheritance, I derive my CBaseCtrl from System.Window.Forms.UserControl
and then derive each control from that, e.g. CButtonCtrl : CBaseCtrl.

My initial idea was to make the CBaseCtrl internal abstract and the
CButtonCtrl public but this results in a CS0060 inconsistent
accessibility error. Even if I change the base class to public
abstract so compilation succeeds, when I try to show the designer it
complains that the base class cannot be loaded (because it is
abstract). What is the best way out of this apparent conundrum?

Thanks,

Jeff

Hi,

Define a constructor in CBaseCtrl as private:

private CBaseCtrl(){}

This will prevent the creation of an instance of this class and you do not
have to mark it as abstract.

Ps:
You could declare it as protected if needed.


--
--
Ignacio Machin,
ignacio.machin AT dot.state.fl.us
Florida Department Of Transportation



<(E-Mail Removed)> wrote in message
news:(E-Mail Removed)...
> Hello,
>
> I have a group of custom controls and each control is derived from a
> base class that performs some standard operations and enforces an
> interface by having some abstract methods. Ideally, I don't want my
> base class visible outside the assembly; also no instantiation, and no
> access by nonderived types. Since C# does not allow multiple
> inheritance, I derive my CBaseCtrl from System.Window.Forms.UserControl
> and then derive each control from that, e.g. CButtonCtrl : CBaseCtrl.
>
> My initial idea was to make the CBaseCtrl internal abstract and the
> CButtonCtrl public but this results in a CS0060 inconsistent
> accessibility error. Even if I change the base class to public
> abstract so compilation succeeds, when I try to show the designer it
> complains that the base class cannot be loaded (because it is
> abstract). What is the best way out of this apparent conundrum?
>
> Thanks,
>
> Jeff
>

Hello Ignacio,

Thanks for the quick response. I should have mentioned that I had made
the constructor protected. However, I need to enforce an interface
with some abstract methods within CBaseCtrl so I still need to keep the
class abstract.

Thanks,

Jeff

Ignacio Machin ( .NET/ C# MVP ) wrote:
> Hi,
>
> Define a constructor in CBaseCtrl as private:
>
> private CBaseCtrl(){}
>
> This will prevent the creation of an instance of this class and you do not
> have to mark it as abstract.
>
> Ps:
> You could declare it as protected if needed.
>
>
> --
> --
> Ignacio Machin,
> ignacio.machin AT dot.state.fl.us
> Florida Department Of Transportation
>
>
>
> <(E-Mail Removed)> wrote in message
> news:(E-Mail Removed)...
> > Hello,
> >
> > I have a group of custom controls and each control is derived from a
> > base class that performs some standard operations and enforces an
> > interface by having some abstract methods. Ideally, I don't want my
> > base class visible outside the assembly; also no instantiation, and no
> > access by nonderived types. Since C# does not allow multiple
> > inheritance, I derive my CBaseCtrl from System.Window.Forms.UserControl
> > and then derive each control from that, e.g. CButtonCtrl : CBaseCtrl.
> >
> > My initial idea was to make the CBaseCtrl internal abstract and the
> > CButtonCtrl public but this results in a CS0060 inconsistent
> > accessibility error. Even if I change the base class to public
> > abstract so compilation succeeds, when I try to show the designer it
> > complains that the base class cannot be loaded (because it is
> > abstract). What is the best way out of this apparent conundrum?
> >
> > Thanks,
> >
> > Jeff
> >