From: "Traveler" <traveler AT netti DOT fi>
Newsgroups: comp.lang.c++,comp.os.msdos.djgpp
Subject: Re: GENERAL DATA TYPE (Do you need one ?)
Date: Wed, 21 Mar 2001 15:21:44 +0200
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To: djgpp AT delorie DOT com
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> A doubly-linked list of anything?  Why?  It doesn't make any
> sense to have everything as a potential member of the list.

> > > > // The following would be possible...
> > > > int    x = f();
> > > > long    y = f();
> > >
> > > What would that do?
> > It depends....
> > What would you like it to do ???
>
> Precisely.  When I need some functionality, I put it there.
> And in most cases the way it is implemented and _named_ must
> make some sense for those who read the code.
>
> > (I certainly know what the "Object& getNode(DWORD index)" will do !!!
> :=))
>
> I don't.  What would it do?  Is that a global function?
Itīs a member function of the list which will return any object stored in
the current index position inside the list.
> the 'getNode' method of class List should return the type
> of the List's element.
Yes, if you want to it the standard way which can only return one and only
one type....
"
template <class T>
class List
{
    class    Node
    {
    public:
        Node*    prev;
        T        data;
        Node*    next;
    }    *first;
public:
    T&    getNode(DWORD index)const;
...
...
...
};"
 But as I stated above, I don't see
> any sense of having a generic "list of anything".
>
I have...
> > >
> > > > // So would this...
> > > > int    x = 10;
> > > > int    y = 20;
> > > > Object    tmp;
> > > > tmp = x;
> > > > x = y;
> > > > y = tmp;    // Now, x has 20 & y has 10
> > >
> > > Why can't 'tml' be 'int'?
> > That was just an example....
>
> Bad example, as it turns out.
I addmit....
>
> > Point is it works and it can handle ALL the basic data types
>
> Again, what for?  The whole idea of type-specific programming is
> to make object distinguishable not only by their name (address)
> but by their type as well.
I know, but there might be a need sometimes in the future where you need a
generic type.
When you do give me a call :)
>
> >
> > You can also use it on those of your own work.
>
> But why?  I will use the type I need, not a generic one.
>
> >
> > The only catch is that A) you have to use inheritance & B) you have to
> > define conversion function that returns some value from your object
>
> There is no need.  A generic "replacement for everything" object
> will be _unable_ to do anything -- it simply will not be able to
> have _any_ functionality.
Are you sure ??? :)
Besides, we already have a type for
> that.  It's called "pointer to void".
>
Yeah, if you want to do those type conversions by hand...
void*    p;
p = (int*)new int[500];