This is really a petty thing, so please excuse me, ... but I'm occasionally troubled by not knowing how a class is being derived. There is no quick way to tell if the first identifier after the ':' is another class or an interface. It probably doesn't matter, of course.

Anyhow, although the documentation states that the syntax is ...

 ClassDeclaration:
 'class' Identifier [SuperClass {, InterfaceClass }] ClassBody

 SuperClass:
 ':' Identifier

 InterfaceClass:
 Identifier


it should really be more like ...

 ClassDeclaration:
 'class' Identifier [ClassDerivation] ClassBody

 ClassDerivation:
 ':' (SuperClass | InterfaceClass) {',' InterfaceClass}

 SuperClass:
 Identifier

 InterfaceClass:
 Identifier

Because the first item can be either a class or an interface. The current syntax documentation implies that it can only be a class, but that is not correct.

I was thinking that the production ClassDerivation could be changed slightly to ...

 ClassDerivation:
 ':' [(SuperClass | InterfaceClass)] {',' InterfaceClass}

such that we could write ...

  class Foo : ,iOne, iTwo {}

and thus explicitly show that the first identifier in the derivation list is an interface. Of course, this wouldn't help with code written under the current syntax rule.

Or if one really wants to get wordy...

  class Foo: parent BaseFoo, interface iOne, iTwo {}

This might also help get over the apparent confusion that a D interface is like a lightweight abstract class, which it is not.

-- 
Derek
Melbourne, Australia
30/Jul/04 2:07:43 PM

Derek Parnell wrote:
> Or if one really wants to get wordy...
> 
>   class Foo: parent BaseFoo, interface iOne, iTwo {}
> 
> This might also help get over the apparent confusion that a D interface is
> like a lightweight abstract class, which it is not.

Hmm, does this look familiar to anybody:

class Foo extends BaseFoo implements iOne, iTwo {}

???

There are a hundred ways of doing this.  I know C++ doesn't care one way
or the other what the parent classes are (assuming you equate a pure
virtual base class to an interface).

Honestly, I think it is clumsy to force a comma for a placeholder of
whether the first element of the dirivation list is not an interface.

What is so bad about the way it currently _works_?  If nothing, then
just change the text that describes it.

> Or if one really wants to get wordy...
>
>   class Foo: parent BaseFoo, interface iOne, iTwo {}

Nah, but almost right ;-) All interfaces names should be previxed with 'I'.

interface IMessageBoxInvoker
{
  MessageBox(char[] message);
}

class MessageBoxInvoker : IMessageBoxInvoker
{
  MessageBox(char[] message) {...}
}

That will prevent name clashes too...

Matt

In article <ceeu8i$e0s$1@digitaldaemon.com>, me says...
>
>Nah, but almost right ;-) All interfaces names should be previxed with 'I'.

Yuck. That is so Microsoft! Interfaces in Java don't all start with "I". The only place this I-rule apprears to be true is in the Microsoft COM world,

Well, the D style guide says "just say no" to hungarian notation, and I rather agree with that.

Arcane Jill

Arcane Jill wrote:

> In article <ceeu8i$e0s$1@digitaldaemon.com>, me says...
> 
>>Nah, but almost right ;-) All interfaces names should be previxed with 'I'.
> 
> 
> Yuck. That is so Microsoft! Interfaces in Java don't all start with "I". The
> only place this I-rule apprears to be true is in the Microsoft COM world,
> 
> Well, the D style guide says "just say no" to hungarian notation, and I rather
> agree with that.

Their .NET coding standard says to prefix interfaces with I as well.

(a peculiar exception to the rule, incidently: except for IInterfaces, pretty much everything is to be written using PascalCase, except for privateAttributes and functionParameters)

 -- andy

"Arcane Jill" <Arcane_member@pathlink.com> wrote in message news:ceiu0n$245s$1@digitaldaemon.com...
> In article <ceeu8i$e0s$1@digitaldaemon.com>, me says...
> >
> >Nah, but almost right ;-) All interfaces names should be previxed with 'I'.
>
> Yuck. That is so Microsoft! Interfaces in Java don't all start with "I". The only place this I-rule apprears to be true is in the Microsoft COM world,
>
> Well, the D style guide says "just say no" to hungarian notation, and I rather agree with that.
>
> Arcane Jill

First, AFAIK, 'I' is also used for interfaces in .NET, so your assertion is not correct. (And I've seen plenty of non-COM C++ code in various clients' code bases.)

If something emanates from Microsoft (or any other specific vendor), does that make it automatically bad? That is a pathetic attitude.

Finally, Hungarian is about decorating _variable_ names with type. The 'I' is part of the _type_ name.