Re: [boost] [bind] private member functions

From: Jeff Flinn (TriumphSprint2000_at_[hidden])
Date: 2008-03-14 08:27:14

Robert Dailey wrote:
> On Thu, Mar 13, 2008 at 5:43 PM, Giovanni Piero Deretta <gpderetta_at_[hidden]>
> wrote:
> 
>> On Thu, Mar 13, 2008 at 11:18 PM, Robert Dailey <rcdailey_at_[hidden]>
>> wrote:
>>> Hi,
>>>
>>>  Currently I have a class named Foo. Foo is using Boost.Bind to bind one
>> of
>>>  its own private methods to *this. However, since the method I'm binding
>> is
>>>  private, boost.bind cannot call it.
>> This compiles for me with gcc:
>>
>> #include <boost/bind.hpp>
>> class foo {
>> private:
>>  void do_bind() {
>>    int i = boost::bind(&foo::m, _1)(this);
>>  }
>>  int m;
>> };
>>
>> in fact the privateness of the member shouldn't matter.
>> Once you extract the pointer to member, access control doesn't matter
>> any longer.
>> Of course you need to extract the pointer to member inside a member
>> function or a friend of the class,
>> but bind shouldn't have nothing to do with that.
>>
>>>  Is there a way to make Boost.Bind a
>>>  friend of my class? What is the recommended solution to such a problem?
>> I
>>>  did some quick searching on google about this issue but I came up with
>> no
>>>  results. Thanks.
>> What is the problem you are encountering exactly?
> 
> 
> The private member function I'm binding is being passed into
> Boost.Signalslibrary, and that is where the function object is being
> evoked. Perhaps that
> is the issue? The function bound by Boost.Bind() is being evoked outside of
> the scope of the owning class. Perhaps Boost.Signals needs to be a friend?
> When I get into work tomorrow I'll give you an exact compiler error message,
> if you require it. The compiler error itself wasn't at all helpful, it was
> simply my assumption that binding a private member function to
> boost.bindwasn't going to work.

Your postings do not clearly specify the compiler error and it's 
context. Could you post the compiler error and the code it's related to?

The only access issue I've encountered is something like(I don't 
remember the exact problem):

struct base
{
...
protected:
    virtual void f(){}
}

struct derived
{
...

    void bind_user()
    {
        bind(&base::f, _1); // compile error

        bind(&derived::f, _1); // ok
    }
}

Jeff Flinn