./graph_structures.d(124): Error: class graph_structures.node(D,
E) is used as a type

I have no idea what this means:( Once we create a class, the
textbook examples show its use as a type which I believe is what
C++ & Java allow. Here's some code:

class node(D, E) {
     int nid;
     D data;
     E[] in_edges; // All edges for undirected graphs go here.
     E[] out_edges; // Only used by directed graphs

     this(D, E)(D data, int n) {
         this.data = data;
         nid = n;
         in_edges = new E[];
         out_edges = new E[];
     }

This is incomplete, but I believe the relevant stuff is my node
template uses 2 parameters corresponding to the data types for
the stored data and the edge types. Here's statement 124 in main:

     auto fee = new node(string, u_edge)("Suck Moose", 1);

I pass the 2 data types in the first parm list and the
constructor required arguments in the second list. I must be
missing something, but I don't see it:(

Thanx for any help - Charlie

On Tue, Jun 03, 2014 at 03:17:09AM +0000, Charles Parker via Digitalmars-d-learn wrote:
> ./graph_structures.d(124): Error: class graph_structures.node(D,
> E) is used as a type
> 
> I have no idea what this means:(

It usually means you tried to use an uninstantiated template as a type.


[...]
>      auto fee = new node(string, u_edge)("Suck Moose", 1);
[...]

You're missing the compile-time argument "!" operator; this line should be written as:

      auto fee = new node!(string, u_edge)("Suck Moose", 1);

Hope this helps.


T

-- 
Too many people have open minds but closed eyes.

On Tuesday, 3 June 2014 at 03:17:10 UTC, Charles Parker wrote:
> ...
> Thanx for any help - Charlie

Well one thing is that you don't need the type parameters on the
this function. You're basically creating a templated this inside
the templated class which is not what you want.

try this:

     class node(D, E) {
         int nid;
         D data;
         E[] in_edges; // All edges for undirected graphs go here.
         E[] out_edges; // Only used by directed graphs

         this(D data, int n) {
             this.data = data;
             nid = n;
             in_edges = new E[];
             out_edges = new E[];
         }

Another thing is that you're missing the ! to instantiate

                        v
     auto fee = new node!(string, u_edge)("Suck Moose", 1);
                        ^

On Tuesday, 3 June 2014 at 03:35:46 UTC, Chris Cain wrote:
> On Tuesday, 3 June 2014 at 03:17:10 UTC, Charles Parker wrote:
>> ...
>> Thanx for any help - Charlie
>
> Well one thing is that you don't need the type parameters on the
> this function. You're basically creating a templated this inside
> the templated class which is not what you want.
>
> try this:
>
>      class node(D, E) {
>          int nid;
>          D data;
>          E[] in_edges; // All edges for undirected graphs go here.
>          E[] out_edges; // Only used by directed graphs
>
>          this(D data, int n) {
>              this.data = data;
>              nid = n;
>              in_edges = new E[];
>              out_edges = new E[];
>          }
>
> Another thing is that you're missing the ! to instantiate
>
>                         v
>      auto fee = new node!(string, u_edge)("Suck Moose", 1);
>                         ^
Chris, that was it I needed to do both things. It then complained
about trying to allocate the in_edges and out_edges arrays in the
constructor which is how I thought dynamic arrays are allocated
on the heap. I removed the 2 new statements, and both compile and
execution of my initial test worked.

Thanx - Charlie

On 03/06/14 05:57, Charles Parker wrote:

> Chris, that was it I needed to do both things. It then complained
> about trying to allocate the in_edges and out_edges arrays in the
> constructor which is how I thought dynamic arrays are allocated
> on the heap. I removed the 2 new statements, and both compile and
> execution of my initial test worked.

You don't really need to allocate the arrays. You can just declare them and start using them:

int[] foo;
foo ~= 4; // append 4 to the array

Arrays in D are a implemented as a struct with a pointer to the data and a field with the length of the array.

-- 
/Jacob Carlborg