On 8/2/17 11:52 AM, H. S. Teoh via Digitalmars-d-learn wrote:
On Wed, Aug 02, 2017 at 08:20:23AM -0400, Steven Schveighoffer via
Digitalmars-d-learn wrote:
On 8/1/17 7:44 PM, H. S. Teoh via Digitalmars-d-learn wrote:
[...]
You can iterate a const AA, but if you want to iterate a non-const AA,
you need a different type.
For instance, if your AA is int*[string], you will get const(int*) out
of it, which may not be what you want.
Unless your range is a slice or a pointer, then you can't do it
properly without having separate types for const, immutable, mutable
ranges. You can use templates to build them, but it's not
straightforward or pleasant.
[...]
Hmm. This seems like a perfect use case for inout, though I'm not
confident the current implementation of inout can handle this. You'd do
something like this:
auto byPair(AA)(inout(AA) aa)
{
struct Result
{
inout(Slot)* current;
... // range primitives here
}
return Result(aa);
}
What I'm unsure of is whether the current implementation of inout can
handle the inout inside the definition of Result.
It's not currently legal, you can't have inout members of a struct. This
could be added, but it still wouldn't work, because you can't "strip
off" the inout part upon return.
The real answer is to have tail modifiers for structs, so you can do the
same thing an array does. Note that if Result is an array, you CAN use
inout:
auto byPair(AA)(inout(AA) aa)
{
alias Result = inout(X)[];
return Result(...);
}
-Steve
