New structs

[Andrej Mitrovic]

Is this D1 code? Because in D2:

S2* c = new S1(); //  Error: cannot implicitly convert expression (new
S1) of type S1* to S2*

S2* d = cast(S2*) GC.malloc(S2.sizeof);
d = S2();  // Error: cannot implicitly convert expression (S2(0)) of
type S2 to S2*

Neither of those work.

On Fri, Sep 10, 2010 at 7:27 PM, JMRyan <nospam at nospam.com> wrote:
> Consider this uninspiring pair structs:
>
> struct S1 {int x};
> struct S2
> {
>    int x
>    this(int i) {x = i}
> };
>
> Note that no default constructor is allowed so that S2.init can have a
> consistent value computed at compile time.
>
> Now:
>
> S1 a = S1();       // Quintessinal case works fine
> S2 b = S2();       // Also works, D initializes b with S2.init
> S2* c = new S1();  // Works, D initializes c* with S2.init
> S2* d = new S2();  // Doesn't work: no default consructor
>
> Instead of the last, we need:
>
> S2* d = cast(S2*) GC.malloc(S2.sizeof);
> d = S2();  // or: d = S2.init;
>
> Is there any good reason why "S2* d = new S2();"
> shouldn't be allowed? If allowed, D could initialize d* with S2.init.
>
> S2 really isn't needed since S1(3) and S2(3) have the same effect.
> Also, a final class would at least usually be just as good as a struct
> here.  But still, disallowing "S2* d = new S2();" seems decidedly
> unnecessary, especially since "S2 b = S2();" already works.
>