Re: [Boost-users] Having trouble with a callback function (converted to a class) in Regex

Subject: Re: [Boost-users] Having trouble with a callback function (converted to a class) in Regex
From: Ramon F Herrera (ramon_at_[hidden])
Date: 2009-09-17 18:20:51

It seems that the problem I am having is related to this:

http://www.parashift.com/c++-faq-lite/pointers-to-members.html

Still, I would appreciate your kind assistance...

TIA,

-Ramon

Ramon F Herrera wrote:
> 
> Hello,
> 
> This is my first non-trivial, multi-file C++ program with classes and I 
> bumped into a problem. See example from the Regex library below.
> 
> The problem occurred after I converted the simple code below to a class 
> (called "Pairs"). The troublesome statement is this one, where we 
> attempt to take the address of a function.
> 
> std::for_each(m1, m2, &regex_callback);
> 
> My first compilation attempt produces an error message from the 
> compiler, which is nice enough to offer a solution:
> 
> pairs.cpp:247: error: ISO C++ forbids taking the address of an 
> unqualified or parenthesized non-static member func
> tion to form a pointer to member function.  Say 
> `&Pairs::assignment_callback'
> 
> So, following the compiler's suggestion, I changed the line above to this:
> 
> std::for_each(m1, m2, &Pairs::assignment_callback);
> 
> Now, I am getting an inscrutable (for me, anyway) error message:
> 
> stl_algo.h:158: error: must use .* or ->* to call pointer-to-member 
> function in `__f (...)'
> 
> Thanks for your kind assistance,
> 
> -Ramon
> 
> 
> ===================================================
> 
> int main(int argc, const char** argv)
> {
>   std::string text;
>   for(int i = 1; i < argc; ++i)
>   {
>   cout << "Processing file " << argv[i] << endl;
>   std::ifstream fs(argv[i]);
>   load_file(text, fs);
>   // construct our iterators:
>   boost::sregex_iterator m1(text.begin(), text.end(), expression);
>   boost::sregex_iterator m2;
>   std::for_each(m1, m2, &regex_callback);
>   // copy results:
>   cout << class_index.size() << " matches found" << endl;
>   map_type::iterator c, d;
>   c = class_index.begin();
>   d = class_index.end();
>   while(c != d)
>   {
>   cout << "class \"" << (*c).first << "\" found at index: " << 
> (*c).second << endl;
>  ++c;
>  }
>   class_index.erase(class_index.begin(), class_index.end());
>   }
> return 0;
> }