The demise of T[new]

[downs]

Walter Bright wrote:
> The purpose of T[new] was to solve the problems T[] had with passing T[]
> to a function and then the function resizes the T[]. What happens with
> the original?
> 
> The solution we came up with was to create a third array type, T[new],
> which was a reference type.
> 
> Andrei had the idea that T[new] could be dispensed with by making a
> "builder" library type to handle creating arrays by doing things like
> appending, and then delivering a finished T[] type. This is similar to
> what std.outbuffer and std.array.Appender do, they just need a bit of
> refining.
> 
> The .length property of T[] would then become an rvalue only, not an
> lvalue, and ~= would no longer be allowed for T[].
> 
> We both feel that this would simplify D, make it more flexible, and
> remove some awkward corner cases like the inability to say a.length++.
> 
> What do you think?

I think ArrayBuilder can work almost entirely transparently provided the following conditions are met:

1) when trying to cat to an array, the first array automatically promotes to ArrayBuilder

2) Setting .length is, depending on new length, either a slice or a cat operation with the length difference.

2) ArrayBuilders implicitly cast to string.

This should allow a syntax that is almost entirely identical to the one used in D1, aside from typeof("a"~"b").stringof :)

Is this feasible in D2?