Re: [Boost-users] Iterating over the output of a member function in std::for_each

Subject: Re: [Boost-users] Iterating over the output of a member function in std::for_each
From: Andrew Hundt (athundt_at_[hidden])
Date: 2012-03-01 18:13:59

Aha! I had to add:

    typedef void result_type;

to the body of the avg object. Then your example:

    for_each(values.begin(), values.end(),
     bind(avg, bind(&value_wrapper_type::getValue, _1))
    );

Worked perfectly! Thank you very much for the help Mathias, it is
greatly appreciated.

Cheers!
Andrew Hundt

On Thu, Mar 1, 2012 at 2:44 PM, Mathias Gaunard
<mathias.gaunard_at_[hidden]> wrote:
> On 03/01/2012 05:52 PM, Andrew Hundt wrote:
>>
>> I have a class with an accessor member function that I want to call and
>> apply the result to a functor using std::for_each. I have a working
>> version below that uses a for loop and for_each, but the for_each
>> version is cryptic and cumbersome. Is there a way I can make the
>> for_each version more concise?
>>
>>     #if 0
>>        // for loop version:
>>        for(value_vector_type::iterator it = values.begin();
>> it!=values.end(); it++){
>>          avg(it->getValue());  // I want to put this in a for_each loop
>>        }
>>     #else
>>       //  bind version:
>>       std::for_each(values.begin(), values.end(), // iterate over all
>> values
>>         boost::bind(
>>           boost::mem_fn(&average_type::operator()), // attach the
>> averaging functor to the output of the getvalue call
>> &avg,
>>           boost::bind(
>>             boost::mem_fn(&value_wrapper_type::getValue), // bind the
>> getValue call to each element in values
>>             _1
>>           )
>>         )
>>       );
>>     #endif
>
>
> for_each(values.begin(), values.end(),
>  bind(avg, bind(&value_wrapper_type::getValue, _1))
> );
>
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