Re: Template: given: the method, searched: the class

From:

Thomas Maeder <maeder@glue.ch>

Newsgroups:

comp.lang.c++.moderated

Date:

Tue, 9 Oct 2007 15:31:27 CST

Message-ID:

<m2zlysxom4.fsf@glue.ch>

t.lehmann@rtsgroup.net writes:

see following code example (working mechanism):
- - -
struct X{ void test(bool); };
std::for_each(xcont.begin(), xcont.end(), use_method<X>(&X::test,
true));
- - -

Is it possible to write the 'use_method' like this:
- - -
std::for_each(cont.begin(), cont.end(), use_method(&X::test, true));
- - -

Something like this?

#include <algorithm>
#include <vector>

struct X
{
    void test(bool) {}
};

template <typename T, typename P>
class method_wrapper
{
  public:
    method_wrapper(void (T::*f)(P), P p)
      : myF(f)
      , myP(p)
    {
    }

    void operator()(T &t)
    {
      (t.*myF)(myP);
    }

  private:
    void (T::*myF)(P);
    P myP;
};

template <typename T, typename P>
method_wrapper<T,P> use_method(void (T::*f)(P), P p)
{
  return method_wrapper<T,P>(f,p);
};

int main()
{
  std::vector<X> cont;
  std::for_each(cont.begin(), cont.end(), use_method(&X::test, true));
}

Similar, more general functionality can be found in the Standard C++
Library and the Boost library.

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