Re: (variadic) templates and storing pointers to (arbitrary) member functions

From:
SG <s.gesemann@gmail.com>
Newsgroups:
comp.lang.c++
Date:
Thu, 25 Jun 2009 00:15:48 -0700 (PDT)
Message-ID:
<6145d075-3a6a-4b75-a99e-08e5833c7e09@m18g2000vbi.googlegroups.com>
On 25 Jun., 08:54, Michael Haupt <mha...@gmail.com> wrote:

I've asked this on the gcc-help mailing list already but was
redirected to this group as the question seemed to be too C++
specific. So, apologies to all that have seen this already.

What I would like to do is create a map<s, f> mapping some symbol type
to functions (the latter are member functions of classes).

My problem is that I am stuck defining the correct type for f. It
should be able to represent member functions of arbitrary classes,
with arbitrary parameter lists.


How would you use such a map (and call the functions?)

  iter_t it = map.find("my symbol");
  if (it!=map.end()) {
    it->second(); // <-- like this?
  }

My understanding of the problem is that what I really want is a
partial instantiation of the template that still leaves the A...
unbound, creating a more generic type.

Is that possible at all?


No. Instead, try runtime polymorphism:

  map<std::string,std::tr1::function<void()> > map;

You can initialize a function<> object with pretty much any kind of
functor object as long as the "signature is compatible". This includes
functors like bind1st(mem_fun(&T::foo),&t).

Cheers!
SG

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