Re: [Boost-users] [Accumulators] Errors compiling the "Hello, World!" example

Subject: Re: [Boost-users] [Accumulators] Errors compiling the "Hello, World!" example
From: Eric Niebler (eric_at_[hidden])
Date: 2010-01-11 05:37:37

On 1/11/2010 10:05 AM, Marco Guazzone wrote:
> Hello!
>
> I'm new to Accumulators.
> I've tried to compile the "Hello, World!" example (found in the User
> Guide) but it fails:
>
> --- [error] ---
> $ g++ -ansi -Wall -o accumulators_test1 accumulators_test1.cpp
>
> /usr/include//boost/accumulators/statistics_fwd.hpp: In function ‘int main()’:
> /usr/include//boost/accumulators/statistics_fwd.hpp:87: error:
> ‘template<int N>  struct boost::accumulators::tag::moment’ is not a
> function,
> /usr/include//boost/accumulators/statistics/moment.hpp:104: error:
> conflict with ‘template<int T2, class Arg1, class A0, class A1, class
> A2, class A3, class A4, class A5, class A6, class A7, class A8, class
> A9, class A10, class A11, class A12, class A13, class A14>  typename
> boost::accumulators::detail::extractor_result<Arg1,
> boost::accumulators::tag::moment<T2>  >::type
> boost::accumulators::extract::moment(const Arg1&, const A0&, const
> A1&, const A2&, const A3&, const A4&, const A5&, const A6&, const A7&,
> const A8&, const A9&, const A10&, const A11&, const A12&, const A13&,
> const A14&)’
> accumulators_test1.cpp:22: error:   in call to ‘moment’
> --- [/error] ---

<snip>

> Where I am wrong?

Marco,

You are not wrong. With my hello world example, I have inadvertently led 
you into the murky waters of C++ name look-up. GCC does it one way, the 
rest of the world does it another, and you are caught in the fray. If 
you qualify the call to moment (accumulators::moment<2>(acc)), the 
problem will go away.

I'll fix the docs for 1.42 and see if there's something can be done in 
the library to obviate the need for qualification in the future.

Sorry for the trouble,

-- 
Eric Niebler
BoostPro Computing
http://www.boostpro.com