Allowing "fall through" of attributes

Rufus Smith via Digitalmars-d-learn digitalmars-d-learn at puremagic.com
Tue Jul 19 10:05:55 PDT 2016


On Tuesday, 19 July 2016 at 16:59:48 UTC, Lodovico Giaretta wrote:
> On Tuesday, 19 July 2016 at 16:50:56 UTC, Rufus Smith wrote:
>> On Tuesday, 19 July 2016 at 16:09:38 UTC, Lodovico Giaretta 
>> wrote:
>>> [...]
>>
>> But this doesn't create a function with all the attributes of 
>> the original? Just one that has the same return type and 
>> parameters. What if Fun is pure or extern(C) or some other 
>> attributes? I'd like to create a function that is exactly the 
>> same in all regards as the original.
>
> Sorry, I misunderstood your question.
> With the method I showed you, if the function is @safe, pure, 
> @nogc or nothrow, foo will infer those attributes. But only if 
> the operations you do in foo (apart from calling bar) are 
> themselves @safe, pure, @nogc or nothrow.
> For other things, like extern(C), I don't think there's a 
> simple solution; but I'm not an expert, so I hope someone else 
> will give you a better answer.

What is strange is I cannot even pass an extern(C) function to 
foo.

void foo(R, A...)(R function(A) bar);

extern(C) void bar();

foo(&bar)

fails. Remove extern and it passes. I have not figured out how to 
allow for extern(C) functions to be passed.


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