[boost] [concept_check] addable

Subject: [boost] [concept_check] addable
From: lcaminiti (lorcaminiti_at_[hidden])
Date: 2012-04-20 01:22:18

Dave Abrahams wrote
> 
> on Thu Apr 19 2012, lcaminiti <lorcaminiti-AT-gmail.com> wrote:
> 
>> Hello all,
>>
>> Does this Addable concept definition make sense to you? 
> 
> Well, it "makes sense," but...
> 
>> Is there any error?
> 
> That depends on what concept constraints you're trying to express.  This
> definition tests that x + y is convertible to T.
> 

I wanted to check that there exist an operator+ from T x T to T "T
operator+(T, T)" so I think that is what Addable<T> checks... maybe the
Sun's linker errors below are from something else (I've changed a regression
test to get more info when it cycles tomorrow).

>> #include &lt;boost/concept_check.hpp&gt;
>>
>> template<typename T>
>> struct Addable { // User-defined concept.
>>     BOOST_CONCEPT_USAGE(Addable) {
>>         return_type(x + y); // Check addition `T operator+(T x, T y)`.
>>     }
>>
>> private:
>>     T x;
>>     T y;
>>
>>     void return_type(T const&); // Used to check addition returns type
>> `T`.
>> };
>>
>> It's not making Sun's linker happy:
>>
>> "/opt/sunstudio12.1/bin/CC" -g -library=stlport4 -features=tmplife
>> -features=tmplrefstatic -library=stlport4 -m64 -KPIC   -o
>> "/scratch2/kbelco/boost/results/boost/bin.v2/libs/local_function/test/typeof_seq.test/sun-5.10/debug/address-model-64/stdlib-sun-stlport/typeof_seq"
>> "/scratch2/kbelco/boost/results/boost/bin.v2/libs/local_function/test/typeof_seq.test/sun-5.10/debug/address-model-64/stdlib-sun-stlport/typeof_seq.o" 
>> -Bdynamic -lrt -Bstatic  -Bdynamic
>>
>> Undefined???first referenced
>>  symbol  ???    in file
>> void Addable<int>::return_type(const int&)
>> /scratch2/kbelco/boost/results/boost/bin.v2/libs/local_function/test/typeof_seq.test/sun-5.10/debug/address-model-64/stdlib-sun-stlport/typeof_seq.o
>> ld: fatal: Symbol referencing errors. No output written to
>> /scratch2/kbelco/boost/results/boost/bin.v2/libs/local_function/test/typeof_seq.test/sun-5.10/debug/address-model-64/stdlib-sun-stlport/typeof_seq
>>
>> But the error might also be somewhere else in the program that checks the
>> concept, I'm still debugging...
> 

Thanks,
--Lorenzo

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