• Cheng Wei (14/14) Oct 13 2011 import std.c.stdio
• bearophile (5/16) Oct 13 2011 _aaApply2 is the function used to iterate on the associative array. It i...
• Cheng Wei (3/3) Oct 13 2011 Thanks.
• bearophile (4/6) Oct 13 2011 I see. Now in D there is purity/"throwbility" inference for templates. I...
• Cheng Wei (6/6) Oct 13 2011 Yeah, the problem could be solved if _aaApply2 was a template instead of
• Steven Schveighoffer (6/11) Oct 13 2011 No, but I see no reason why _aaApply2 couldn't be overloaded with

Cheng Wei <rivercheng gmail.com> writes:

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.

bearophile <bearophileHUGS lycos.com> writes:

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

Cheng Wei <rivercheng gmail.com> writes:

Thanks.

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

bearophile <bearophileHUGS lycos.com> writes:

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

Cheng Wei <rivercheng gmail.com> writes:

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.

"Steven Schveighoffer" <schveiguy yahoo.com> writes:

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