On Wednesday, 11 January 2017 at 19:23:10 UTC, Razvan Nitu wrote:
Hi,
I am currently trying to create a function
makeMultidimensionalArray which allocates memory for a
multidimensional array. It is very similar with [1],
the difference being that it is uninitialized. Here is the code:
auto makeMultidimensionalArray(T, Allocator)(auto ref Allocator
alloc, size_t[] lengths)
{
if (lengths.length == 1)
{
return makeArray!T(alloc, lengths[0]);
}
else
{
alias E = typeof(makeMultidimensionalArray!T(alloc,
lengths[1..$]));
auto ret = makeArray!E(alloc, lengths[0]);
foreach (ref e; ret)
e = makeMultidimensionalArray!T(alloc,
lengths[1..$]);
return ret;
}
}
The lengths[] specifies the lengths for each dimension. The
problem with this code is that auto is going to be evaluated to
T[] for the first time and when it
recurs, creating T[][] I get the error "mismatched function
return type inference of T[][] and T[]". Is there a way to
surpass that? I saw that in [1]
the recursive call is done by prefixing the function name with
a '.'; I tried that but it doesn't work. I must be missing
something, any ideas?
Thanks,
RazvanN
[1]
https://github.com/dlang/phobos/blob/master/std/experimental/ndslice/slice.d#L834
This is probably not possible. You are trying to have multiple
return types for the same function. You are thinking that each
recursive call is a new template but that doesn't seem to be the
case.
Instead, maybe try using string mixins to generate the
allocations. Should be quite easy and will work.
You could also try to use a helper function that you pass the
fully declared array(all dimensions) and the helper function then
allocates each dimension recursively... The difference is that
you are not passing around/returning sub-arrays so you don't have
to worry about type mismatches.
