Compilable Recursive Data Structure ( was: Recursive data structure using template won't compile)

[Nick Sabalausky]

On Sat, 10 Nov 2012 10:33:39 +0000 (UTC)
Manfred Nowak <svv1999 at hotmail.com> wrote:

> Nick Sabalausky wrote:
> 
> > I really don't see the relevance
> 
> Please look at the definition of R:
> struct R
> {
>     int value;
>     d_list!R Rlist;
> }
> 
> If no recursion was wanted the OP should have written:
>     d_list!(R*) Rlist;
> 

Ok, I see what you're saying, but you're mistaken: That line "d_list!R
Rlist;" is not a problematic recursion.

Imagine if d_list had been defined like this:

struct d_list(T)
{
    int i;
}

Then would this still be problematic recursion?:

struct R
{
    d_list!R Rlist;
}

No, because R is never actually used anywhere in that d_list (only
int is used). In this case, R is nothing more that part of the *name* of
a particular instantiation of the d_list template.

And indeed, just like the above example, the OP's definition of d_list
also does *not* use R:

struct d_list( T )
{
    node* head;
    node* tail;
}

Now, yes, that "node" type does use R (instead of R*), *but* "head"
and "tail" are merely pointers to "node", so it's ok.

> In digitalmars.D.learn:40990 I already asked for an explanation.
> 

Actually, my newsreader is kinda shitty, and (AFAIK) doesn't give me
any way to lookup a message by ID, so I'm not really sure which message
you're referring to :/