Shouldn't AAs be using a range interface instead of opApply these days? Is really there any reason for a foreach over an AA not to be nothrow?

On Sunday, 21 July 2024 at 16:44:56 UTC, IchorDev wrote:

Probaly history, ranges were d2, aa's in d1 look basically the same https://digitalmars.com/d/1.0/hash-map.html

On Sunday, 21 July 2024 at 16:44:56 UTC, IchorDev wrote:

The range interface doesn’t really support key–value pair iteration. An AA can be iterated by values or keys and values. A range interface can’t do that. The issue is that iteration isn’t nothrow, but I don’t know why. It makes no sense.

On Monday, 22 July 2024 at 11:11:53 UTC, Quirin Schroll wrote:

Yes it does?

Indeed, only one or the other. We should really fix this somehow though, because opApply sucks with all of D’s different function attributes.

I guess because the function calls an un-marked delegate? I’m not even sure how I’m able to call it in @safe code though, and yet it supposedly uses the GC just for iteration? And heaven forbid C code tries to call it, since it’s extern(C) but supposedly throws…

On Monday, 22 July 2024 at 15:28:45 UTC, H. S. Teoh wrote:

The struct has one loop value instead of two though, so you have to rewrite code to use .key and .value, which is not as good as being able to name the key & value yourself. It would’ve been possible for it to be implemented differently though: https://dlang.org/spec/statement.html#front-seq

On Monday, 22 July 2024 at 15:49:54 UTC, IchorDev wrote:

front can't return a tuple, because the range has to store a pointer to a value so front.value can be mutated.

On Monday, 22 July 2024 at 15:25:32 UTC, IchorDev wrote:

See https://issues.dlang.org/show_bug.cgi?id=21236.

It's @safe for the compiler to generate a call to it if the loop body is @safe. If the body wasn't safe, there would be an error anyway.

Do you have an example? The following compiles:

void main() @nogc
{
    int[string] aa;
    foreach (k, v; aa)
        assert(v);
}

On Monday, 22 July 2024 at 15:28:45 UTC, H. S. Teoh wrote:

Not in the way it’s supposed to. foreach (v; aa) is supposed to run over values and foreach (k, v; aa) over keys k and values v. From the range interface, front can only return one thing. If it’s a tuple that can decay into two values, sure the k, v one works, but the v one gives you tuples, not values.

On Monday, 22 July 2024 at 16:00:05 UTC, Nick Treleaven wrote:

This won’t be an issue anymore once we have ref fields.