import std.c.stdio

int[int] g_map;

void main() {
    test();
}

nothrow void test() {
    foreach(k, v) {
       printf("%d, %d\n", k, v);
    }
}
Cannot compile with the error:

Error: _aaApply2 is not nothrow

It is not so convenient that we have to use try-catch for all iteration even when we know that it will not throw at all.

Cheng Wei:

> nothrow void test() {
>     foreach(k, v) {
>        printf("%d, %d\n", k, v);
>     }
> }
> Cannot compile with the error:
> 
> Error: _aaApply2 is not nothrow
> 
> It is not so convenient that we have to use try-catch for all iteration even when we know that it will not throw at all.

_aaApply2 is the function used to iterate on the associative array. It is not yet tagged with "nothrow" so you can't yet use it in an nothrow function. This is a known bug that is already in Bugzilla and will be fixed.

I think it's not hard to add those tags, so if you want you will probably be able to create a little pull request that fixes this even if you don't know much about compilers.

Bye,
bearophile

Thanks.

The problem is that if we tag _aaApply2 as nothrow, then can we still put throwable codes in the body of foreach?

Cheng Wei:

> The problem is that if we tag _aaApply2 as nothrow, then can we still put throwable codes in the body of foreach?

I see. Now in D there is purity/"throwbility" inference for templates. Is _aaApply2 allowed to become a template?

Bye,
bearophile

Yeah, the problem could be solved if _aaApply2 was a template instead of a function.

Alternatively, maybe the compiler can skip the purity/throwbility check for __aaApply2 and directly check the statements inside. That means to treat the compiler generated function __aaApply2 differently than the opApply provided by users.

On Thu, 13 Oct 2011 06:16:59 -0400, bearophile <bearophileHUGS@lycos.com> wrote:

> Cheng Wei:
>
>> The problem is that if we tag _aaApply2 as nothrow, then can we still
>> put throwable codes in the body of foreach?
>
> I see. Now in D there is purity/"throwbility" inference for templates. Is _aaApply2 allowed to become a template?

No, but I see no reason why _aaApply2 couldn't be overloaded with nothrow/pure versions.  The underlying code would probably be a template since the actual code is no different.

-Steve