Hi there,

in C++, it is very common to return references to allow assignment. I would like to do something similar in D:

--------------------------
class Vector(T) {
        T[] data;
        this(int size) { data.length = size; }
        T& operator(int idx) { return data[idx]; };
};

int
main() {
        Vector!(int) a(3);
        a(2) = 5;
};
--------------------------

However, that T& is not defined in D. What do I do?

Ciao,
Nobbi

Norbert Nemec wrote:

>Hi there,
>
>in C++, it is very common to return references to allow assignment. I would
>like to do something similar in D:
>
>Ciao,
>Nobbi
>  
>
Use a pointer.

-- 
-Anderson: http://badmama.com.au/~anderson/

"Norbert Nemec" <Norbert.Nemec@gmx.de> wrote in message news:c6db59$24t0$1@digitaldaemon.com...
> Hi there,
>
> in C++, it is very common to return references to allow assignment. I
would
> like to do something similar in D:

I would like to be able to do that too!
This way there are inconsistenties between user defined types (like class)
and non-reference types. This could be a problem in templates and generic
algorithms that should work both for builtin types and for user defined
types
the same way :(

> --------------------------
> class Vector(T) {
>         T[] data;
>         this(int size) { data.length = size; }
>         T& operator(int idx) { return data[idx]; };
> };
>
> int
> main() {
>         Vector!(int) a(3);
>         a(2) = 5;
> };
> --------------------------
>
> However, that T& is not defined in D. What do I do?
>
> Ciao,
> Nobbi

"J Anderson" <REMOVEanderson@badmama.com.au> wrote in message news:c6dcii$28jj$2@digitaldaemon.com...
> Norbert Nemec wrote:
>
> >Hi there,
> >
> >in C++, it is very common to return references to allow assignment. I
would
> >like to do something similar in D:
> >
> >Ciao,
> >Nobbi
> >
> >
> Use a pointer.

Pointer has to be dereferenced == more complex code!


> --
> -Anderson: http://badmama.com.au/~anderson/

From: "Norbert Nemec" <Norbert.Nemec@gmx.de>

> Hi there,
>
> in C++, it is very common to return references to allow assignment. I
would
> like to do something similar in D:
>
> --------------------------
> class Vector(T) {
>         T[] data;
>         this(int size) { data.length = size; }
>         T& operator(int idx) { return data[idx]; };
> };
>
> int
> main() {
>         Vector!(int) a(3);
>         a(2) = 5;
> };
> --------------------------
>
> However, that T& is not defined in D. What do I do?
>
> Ciao,
> Nobbi


Why not use opIndex? That's what it's there for...
Type1 opIndex(Type2 index, Type1 value);


--
Christopher E. Miller

Vathix wrote:
> Why not use opIndex? That's what it's there for...
> Type1 opIndex(Type2 index, Type1 value);

a) It is limited to just one index, so it will fail for multidimensional arrays

b) it can only be used for assignments but not for inout parameters etc.

"Norbert Nemec" <Norbert.Nemec@gmx.de> wrote in message news:c6ddf1$2b63$2@digitaldaemon.com...
> Vathix wrote:
> > Why not use opIndex? That's what it's there for...
> > Type1 opIndex(Type2 index, Type1 value);
>
> a) It is limited to just one index, so it will fail for multidimensional arrays
>
> b) it can only be used for assignments but not for inout parameters etc.

I understand. If there were array literals, the index type of opIndex could
be int[], and you could specify like:  arr[[3, 4, 5]] = 4;
:)