What does this mean? (nested abstracts...)

15 Apr 2005 10:42 AM

HAM

One of my friends asked if the followings have any meanings?

'-------------
Public Interface IRenderable
    Sub Render()
    MustInherit Class Engine
        MustOverride Sub TurnOn()
        Interface IAutomatic
            Sub Start()
        End Interface
    End Class
End Interface

Public Class RenderMan
    Inherits IRenderable.Engine
    Implements IRenderable, IRenderable.Engine.IAutomatic

    Public Sub Render() Implements IRenderable.Render
        'Code for implementation
    End Sub

    Public Sub Start() Implements IRenderable.Engine.IAutomatic.Start
        'Code for implementation
    End Sub

    Public Overrides Sub TurnOn()
        'Code for implementation
    End Sub
End Class
'-------------

Does this all comply with the specification of OOP? Just curious...

15 Apr 2005 1:42 PM

Brian Gideon

It will not compile. Interfaces cannot declare types.

Brian

HAM wrote:
Show quoteHide quote

> One of my friends asked if the followings have any meanings?
>
> '-------------
> Public Interface IRenderable
>     Sub Render()
>     MustInherit Class Engine
>         MustOverride Sub TurnOn()
>         Interface IAutomatic
>             Sub Start()
>         End Interface
>     End Class
> End Interface
>
> Public Class RenderMan
>     Inherits IRenderable.Engine
>     Implements IRenderable, IRenderable.Engine.IAutomatic
>
>     Public Sub Render() Implements IRenderable.Render
>         'Code for implementation
>     End Sub
>
>     Public Sub Start() Implements IRenderable.Engine.IAutomatic.Start
>         'Code for implementation
>     End Sub
>
>     Public Overrides Sub TurnOn()
>         'Code for implementation
>     End Sub
> End Class
> '-------------
>
> Does this all comply with the specification of OOP? Just curious...

15 Apr 2005 4:38 PM

HAM

IT WILL! Try it for yourself in VS 2003....
(And probably it is better to look it up in the Object Browser...you'll see
that there is no type in "IRenderable")

(PS: Intellisense went wrong when i first entered the code into the text
editor. Then,
when i complied the class , everything went ok...)

Show quoteHide quote

"Brian Gideon" <briangid***@yahoo.com> wrote in message
news:1113572536.042541.273490@g14g2000cwa.googlegroups.com...
> It will not compile. Interfaces cannot declare types.
>
> Brian
>
> HAM wrote:
>> One of my friends asked if the followings have any meanings?
>>
>> '-------------
>> Public Interface IRenderable
>>     Sub Render()
>>     MustInherit Class Engine
>>         MustOverride Sub TurnOn()
>>         Interface IAutomatic
>>             Sub Start()
>>         End Interface
>>     End Class
>> End Interface
>>
>> Public Class RenderMan
>>     Inherits IRenderable.Engine
>>     Implements IRenderable, IRenderable.Engine.IAutomatic
>>
>>     Public Sub Render() Implements IRenderable.Render
>>         'Code for implementation
>>     End Sub
>>
>>     Public Sub Start() Implements IRenderable.Engine.IAutomatic.Start
>>         'Code for implementation
>>     End Sub
>>
>>     Public Overrides Sub TurnOn()
>>         'Code for implementation
>>     End Sub
>> End Class
>> '-------------
>>
>> Does this all comply with the specification of OOP? Just curious...
>

15 Apr 2005 6:46 PM

Brian Gideon

You are correct. It does compile. I should be more careful about
assuming things about VB.NET based on my experiences with C#.
Actually, Engine is nested inside the interface. You can verify that
with ildasm. It is odd that it is legal in VB.NET, but not C#. It may
have been part of an effort to avoid making C# unnecessarily complex.

Brian

HAM wrote:
Show quoteHide quote

> IT WILL! Try it for yourself in VS 2003....
> (And probably it is better to look it up in the Object Browser...
> you'll see that there is no type in "IRenderable")
>
> (PS: Intellisense went wrong when i first entered the code into the
> text editor. Then, when i complied the class , everything went
> ok...)
>

15 Apr 2005 2:38 PM

Nick Malik [Microsoft]

Your friend is being very colorful and creative.

However, the code below is not legal. It doesn't make much sense either.

Classes inherit interfaces.
By creating an interface that declares a class in it, what intent is the
programmer attempting to describe in the code? Is it the intent that the
object which implement the interface must "have a" member class completely
declared within them? Why not just define that a child class returns an
object of a particular type from a member method? The same structural
purpose would be served.

In this case, the Interface can simply refer to another interface for a
member method.

This allows you to have composition without the byzantine declaration syntax
below.

--
--- Nick Malik [Microsoft]
    MCSD, CFPS, Certified Scrummaster
    http://blogs.msdn.com/nickmalik

Disclaimer: Opinions expressed in this forum are my own, and not
representative of my employer.
   I do not answer questions on behalf of my employer. I'm just a
programmer helping programmers.
--

Show quoteHide quote

"HAM" <hmdzxx5x@hotmaildotcom> wrote in message
news:e3x36faQFHA.924@TK2MSFTNGP14.phx.gbl...
> One of my friends asked if the followings have any meanings?
>
> '-------------
> Public Interface IRenderable
>    Sub Render()
>    MustInherit Class Engine
>        MustOverride Sub TurnOn()
>        Interface IAutomatic
>            Sub Start()
>        End Interface
>    End Class
> End Interface
>
> Public Class RenderMan
>    Inherits IRenderable.Engine
>    Implements IRenderable, IRenderable.Engine.IAutomatic
>
>    Public Sub Render() Implements IRenderable.Render
>        'Code for implementation
>    End Sub
>
>    Public Sub Start() Implements IRenderable.Engine.IAutomatic.Start
>        'Code for implementation
>    End Sub
>
>    Public Overrides Sub TurnOn()
>        'Code for implementation
>    End Sub
> End Class
> '-------------
>
> Does this all comply with the specification of OOP? Just curious...
>
>
>
>

15 Apr 2005 4:37 PM

HAM

"Nick Malik [Microsoft]" <nickmalik@hotmail.nospam.com> wrote in message
news:ZuOdnQ9ymKxJTMLfRVn-gQ@comcast.com...

>the code below is not legal. It doesn't make much sense either.

Well, any illegal code (except for logical bugs) must be trapped by the
compiler I guess...

> Classes inherit interfaces.
> By creating an interface that declares a class in it, what intent is the
> programmer attempting to describe in the code?

I am not going to say that this is a good coding practice or not. However,
there is probably a way to know that If class "RenderMan" has inherited the
"Engine" Class of the IRenerable Interface through "IRenderable.Engine" , it
must also implement the IRenderable interface either. And why not declaring
the whole methods of "IRenderable" in the "Engine" class in the first place?
Probably because the "Render" method will be able to be implemented in
classes that "Also"
happen to have implemented from other interfaces, just one like
"IRenderable.Engine.Automatic"
....

> object which implement the interface must "have a" member class completely
> declared within them? Why not just define that a child class returns an
> object of a particular type from a member method? The same structural
> purpose would be served.

you're right....

> In this case, the Interface can simply refer to another interface for a
> member method.

that's a nice idea, just maybe the nested naming of Interfaces could help to
be more specific of where an interface come or sth.. I don't know!....Wow...
I'm messing up...

> This allows you to have composition without the byzantine declaration
> syntax below.

I 'll tell this to my friend.
Thanks for the help anyway