From: Peter Dimov (pdimov_at_[hidden])
Date: 2006-07-04 19:25:52
Bronek Kozicki wrote:
> Peter Dimov wrote:
>> I suspect there is something I'm missing. Let's use examples:
>>
>> // file1
>>
>> struct tag1;
>> set<tag1>();
>>
>> // file2
>>
>> struct tagl;
>> get<tagl>(); // NULL
>>
>> How can the compiler know that you misspelled tag1 as tagl? It can't.
>
> Indeed, but you can put tag1 in a separate header file and then
> include it. Had you used name nested into namespace (or type) that
> solution would be more obvious. To force it I even proposed to
> require complete type, but I do not insist that it's better (it's
> just different). The point of using tag is that compiler CAN help you
> to guarantee name uniqueness and provide name check. Compiler will
> not help you if you do not ask for it (like in your example). But at
> least you CAN use it, it will provide benefits and will NOT force you
> to use centralized location for all tags or build complex
> infrastructure - simple C++ design with nested names will suffice.
>
> If you use string, compiler will NOT help at all - no name check and
> no uniqueness warranties, unless you have single centralized location
> to store all strings and/or build complex infrastructure to manage
> their uniqueness.
How does your compiler help you spot duplicate tags? Most don't diagnose ODR
violations, and if your tags aren't complete, there isn't even an ODR
violation.