The demise of T[new]

[Leandro Lucarella]

Andrei Alexandrescu, el 19 de octubre a las 11:16 me escribiste:
> >>>I'm missing something? Why this shouldn't work?
> >>It may work, but I was unable to pull it off reasonably well.
> >
> >What problems did you find?
> 
> I thought I explained that above and in several other posts. I have
> the feeling this is going in circles, but let me add one more thing.
> People would want to have a reasonable way of choosing between
> T[new] and T[]. The differences between them are subtle (I have two
> tables showing the primitives of T[] and T[new], which are very
> similar).

If T[new] is "array" and T[] is "slice" as I described them, I see no
subtlety, they are huge differences, one is a dynamic array, the other is
a view on somebody else's memory.

I know you probably hate when people says this (that's what I avoided
doing it before :):
I works very well in Python. You have arrays (well, lists, but the
interface is the same as an array) and slices. I never heard anybody
complaining about that being confusing.

> That static decision concerns future appends to the array,
> which doesn't strike me as something you know from the get-go
> through future iterations of a design. Use of "auto" messes up
> things further: a nice function may choose to return T[new] because
> it just created an array (an implementation detail), but clients may
> find that unexpected.

I don't see much problem. You should always return an array (T[new]) if
you have one, because you can get an slice from it (the inverse is not
true). Because of this, implicit conversion from array to slice can be
a good idea, so people expecting a slice when an array is returned will
never know an array was returned anyways. If you need to keep appending to
the array, you can have the original array and keep appending to it
without any performance hit (no copying, no new allocations).

What's wrong with that?

-- 
Leandro Lucarella (AKA luca)                     http://llucax.com.ar/
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Cuando intenté arrimarle mi brazo
Se puso a hablar de Miller, de Anais Nin y Picasso
Y si osaba intentar robarle un beso
Se ponía a leer de Neruda unos versos
Me hizo mucho mal la cumbiera intelectual