Add asFlatStaticArray

[denis-sh]

asFlatStaticArray adds an ability to view any abject as a single-dimensional static array which is very useful for template code as it eliminates error-prone need to create branches and recursion for static-arrays support.

asFlatStaticArray isn't a to* function as it doesn't create a copy. It creates a view of object. And it is important that it doesn't require to provide any types explicitly.

Example:

int i;
static assert(is(typeof(asFlatStaticArray(i)) == int[1]));
asFlatStaticArray(i) = 5;
assert(i == 5);

int[1][2][3] mdimSArr;
static assert(is(typeof(asFlatStaticArray(mdimSArr)) == int[6]));
asFlatStaticArray(mdimSArr) = [1, 2, 3, 4, 5, 6];
assert(mdimSArr == [[[1], [2]], [[3], [4]], [[5], [6]]]);

Requires pull #924.

[dnadlinger]

I am not too sure about the general usefulness of this – could you name 2-3 distinct use cases for the function?

[denis-sh]

I am not too sure about the general usefulness of this – could you name 2-3 distinct use cases for the function?

What? It is useful for every function auto func(T, ...)(T t, ...) accepting a template parameter and doing something with its field. As examples: supplemental _initializeFrom for emplace (see #949), setInitialState, callCopyConstructors, and callDestructors (see #928).

[andralex]

I'm also not sure about the utility of this. Why so close attention to the minutiae of multidimensional static arrays?

[denis-sh]

First of all, to avoid branches and tail recursion is templates.

[denis-sh]

But asFlatStaticArray also has an unlimited power to foreach everything:

foreach(ref el, t.asFlatStaticArray())
{
    // `el` isn't a static array.
    // Can `is(typeof(el) == struct)` e.g. to check for structs.
}

[andralex]

But asFlatStaticArray also has an unlimited power to foreach everything:

Problem is, this is an unremarkable power to be had. I have seldom been in the situation of (a) dealing with multidimensional static arrays with so many dimensions looping became an issue; and (b) writing code that needs to do the same exact thing with each element regardless of its row/column/etc.

[denis-sh]

As examples from my previous comment aren't enough to change you mind I'll make it package.

[denis-sh]

@9rnsr, @alexrp, @jmdavis, or @AndrejMitrovic, could any of you confirm useless of this pull and close it? Thanks.