Re: [announcement] SYSAPI and SYSSVC for Windows

["Ekkehard Morgenstern" <ekkehard.morgenstern@onlinehome.de>]

"Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de> wrote:
> The problem is to tell the customers, that *their* applications should be
> designed so that *our* DLLs and hardware drivers would not stray into an
> unpredictable state.

What's the problem communicating this to the customer?

> A manual reset event only needed when there could be more than one task
> waiting for the event.

Yes that, and then some. (sorry I don't have time right now to elaborate)

> > C++ is well-defined also, btw. There's already a number of ISO standards
> > for C and C++,
> 
> A *number of* standards, fascinating! (:-))

For Ada, there's also an '83 and a '95 rationale. ;)
 
> Come on! C++ does not have:
> 
> 1. multiple dispatch;

True, except for constructors and destructors. They're always called for all derived classes of an object.

Regular virtual methods have to call the methods of their parent class if so desired.

> 2. dispatch on function result;

True. Not possible w/ C++.

> 3. dispatch on access types;

False. Method overloading based on parameters of different types, even pointer types, is supported.

> 4. differentiation between class-wide and specific types;

Class-wide types in Ada roughly correspond to base classes in C++.

> 5. functions returning class-wide objects on the stack;

True, but you can return a reference to an object. (I'm not sure if passing a reference to a 
temporary object would work)

> 6. streaming / object factory support ('Input, 'Output attributes in Ada);

There are provisions for that in the C++ streams standard library. But I haven't yet read
about the features in Ada you're talking about.

> 7. formal derived type parameter for generics;

False. Of course you can use derived classes or other types in templates.

> Why? The following is OK:
> 
>    type T is limited private;
> private
>    type T is limited record
>       I : aliased Integer;

Yes, but I is an Integer. Discrete types can always be aliased.

In my case, it was an array of aliased types, and I wanted to create an access
to an array element.

> "Aliased" is the keyword for that. Objects of some types are always
> aliased:
> 
>    type T is tagged limited ...;

so I could've just used a tagged limited record?

Like this:

    type T is tagged limited
    record
        A : My_Array_Type;
    end record;

    procedure F ( O : in out T ) is
        Ptr : My_Array_Cell_Ptr;
    begin
        Ptr := O.A(1)'Access;
    end;

Right?

> And finally, if you want to get a pointer in F, then probably
> 
>    procedure F (O : access T);
> 
> is reasonable.

Unfortuantely I cannot pass this on to the entry points of my task. ;)

So I decided to use a regular access types and Limited_Controlled types.