Initialization of std.typecons.RefCounted objects

[Christophe Travert]

Matthias Walter , dans le message (digitalmars.D:172673), a écrit :
> I looked at Bug #6153 (Array!(Array!int) failure) and found that the
>
> This exactly is what makes the following code fail:
> 
> Array!(Array!int) array2d;
> array2d.length = 1;
> array2d[0].insert(1);
> 
> The inner array "array2d[0]" was not initialized and hence the reference
> pointer is null. Since Array.opIndex returns by value, the 'insert'
> method is called on a temporary object and does not affect the inner
> array (still being empty) which is stored in the outer array.
> 
> What do you think about this?
> 
> Must the user ensure that the Array container is always initialized
> explicitly? If yes, how shall this happen since the only constructor
> takes a (non-empty) tuple of new elements. Or shall opIndex return by
> reference?

I think opIndex should return by reference. opIndexAssign is of no help 
when the user want to use a function that takes a reference (here 
Array.insert). It is normal that Array uses default construction when 
someone increases the array's length.

Besides that point, I don't see why default-constructed Array have an 
uninitialised Payload. This makes uninitialised Array behaves 
unexpectedly, because making a copy and using the copy will not affect 
the original, which is not the intended reference value behavior.

Correcting default-initialization of Array would correct your bug, but 
would not correct the wrong behavior of Array when the value returned by 
opIndex is used with a non-const method with other objects (dynamic 
arrays?). So both have to be changed in my opinion.

-- 
Christophe