API

[bearophile via Digitalmars-d]

Andrei Alexandrescu:

> So I'm looking at creation functions and in particular creation 
> functions for arrays.
>
> 1. Follow the new int[n] convention:
>
> auto a = allok.make!(int[])(42);
> assert(a.length == 42);
> assert(a.equal(repeat(0, 42));
>
> 2. Follow the [ literal ] convention:
>
> auto a = allok.make!(int[])(42);
> assert(a.length == 1);
> assert(a[0] == 42);

Both cases are needed. Unfortunately we don't have named 
arguments in D, otherwise you can use the same name for both 
operations, using different arguments.

Also keep in mind that in std.array we have functions like 
assocArray, uninitializedArray, and minimallyInitializedArray.


I suggest to take a look at a similar function in Scala and 
especially in Lisp. Lisp has decades of experience to steal from.

A common desire is to create an array based on a given function 
of its indexes:

immutable a = allok.make!(int[][])(tuple(2, 3), (r, c) => r * 10 
+ c);
==>
[[0, 1, 2], [10, 11, 12]]

This is rather handy when you want to create immutable arrays.


> auto a = allok.make!(int[])(42, uninitialized(5), 44);

 From my experience this is a very uncommon situation, I don't 
remember if I have ever had such need. (In most cases you want an 
initialized or an unitialized array. More rarely you want to 
initialize the first N items and leave M items not initialized).

Bye,
bearophile