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 18:44:38

In my specific case there actually ended up being one small
modification I had to make because bind copied the object:

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

Cheers!
Andrew Hundt

On Thu, Mar 1, 2012 at 6:13 PM, Andrew Hundt <athundt_at_[hidden]> wrote:
> 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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