Re: pass all container elements to member function (for_each and mem_fun_ref)

> class Simple
> {
> };
> 
> class Holder
> {
> 
>      vector<Simple> vec;
> 
>      void Do(const Simple& s) const
>      {
>          // does something with s
>      }
> 
>      void DoAll()
>      {
>          for_each(vec.begin(), vec.end(), mem_fun_ref(&Holder::Do));
>      }
> 
> };
> 
> Here is what I get: term does not evaluate to a function taking 1
> arguments

The third argument of for_each has to be a unary function concept
accepting a ref to element of the container you want to work on.
i.e. a function or functor accepting Simple &.

The mem_fun_ref(class::fun) template returns you a
functor object with a signature (class &,arg1 &). So
it accepts two arguments. A ref to the object and
the argument of the member function. This might be
a bit confusing.

So it looks like you may only build your for_each statement
with pointers to member functions of Simple like:

<snip>

class Simple
{
  void Do() {
   // .. do some on *this
  }
};

....

void DoAll()
{
    for_each(vec.begin(), vec.end(), mem_fun_ref(&Simple::Do));
}

</snip>

If you'd like to have access to the current Holder object
you might want to define a void operator()(Simple &)
and simply call

    for_each(vec.begin(), vec.end(), *this);

or you write a functor (preferable as a inner class)
which holds a reference/pointer to the current Holder
and offers this kind of operator


Hope that helps

O.


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