NAME

       BinopsBase - Class template offering class-type binary operators

SYNOPSIS

       #include <bobcat/binopsbase>

DESCRIPTION

       Classes  may  overload  binary operators. A class named Derived may overload binary operators to suit its
       own needs. It could, e.g., allow two Derived class objects to be added together, or  it  could  define  a
       shift-operation given a size_t right-hand side (rhs) argument.

       The  available  binary  operators  are  *,  /,  %,  +,  -, <<, >>, &, |, and ^ (in this man-page they are
       generically indicated as the `@’ operator). In addition, overloaded operator<< and operator>> for  stream
       insertion and extraction are frequently defined.

       If  a  class  Derived  supports  copy  and/or  move  construction  and  if  it offers a swap member (void
       Derived::swap(Derived &rhs)), and is publicly derived from  FBB::BinopsBase<Derived>  then  once  Derived
       defines a member

           void Class::operator@=(Rhs const &rhs) &&

       defining  the  compound  @-operator  for  anonymous,  temporary  Derived  objects  and a Rhs type for its
       right-hand side operand the following operators are also available:

           Derived &operator@=(Rhs const &rhs) &

           Derived operator@(Derived &&lhs, Rhs const &rhs);
           Derived operator@(Derived const &lhs, Rhs const &rhs);

       A similar procedure applies to the insertion and extraction operators. Insertion and extraction operators
       become  available  once BinopsBase<Derived> is declared a friend class of Derived.  To make the insertion
       operator available a private member

           void Derived::insert(std::ostream &out) const

       must then also be defined, inserting the calling object into out. Analogously,  to  make  the  extraction
       operator available a private member

           void Derived::extract(std::istream &in)

       must be defined extrating the calling object from in.

INHERITS FROM

       --

OVERLOADED OPERATORS

       For  each  defined  Derived  &&operator@=(Rhs  const &rhs) &&, defined in the class Derived the following
       operators are automatically also available:

           Derived operator@(Derived &&lhs, Rhs const &rhs);
           Derived operator@(Derived const &lhs, Rhs const &rhs);

       and

           Derived &operator@=(Rhs const &rhs) &;

       The insertion operator becomew available once

           void Derived::insert(std::ostream &out) const

       (inserting the calling object into out) has been defined. Analogously, the  extraction  operator  becomes
       available after defining a private member

           void Derived::extract(std::istream &in)

       (extracting the calling object from in).

FRIEND DECLARATION

       To make the insertion and/or extraction operators available the class Derived must also declare

           friend FBB::BinopsBase<Derived>;

EXAMPLE

       #include <iostream>
       #include <bobcat/binopsbase>

       class Demo1: public FBB::BinopsBase<Demo1>
       {
           friend FBB::BinopsBase<Demo1>;            // for insert/extract

           public:
               void swap(Demo1 &other)
               {}

               Demo1 &&operator+=(Demo1 const &rhs) &&
               {
                   std::cout << "adding two Demo1 objects\n";
                   return std::move(*this);
               }

       //  Explicit definitions take precedence over functions templates
       //  instantiated from definitions in bobcat/binopsbase.
       //        Demo1 &operator+=(Demo1 const &rhs) &
       //        {
       //            std::cout << "adding (self-defined) two Demo1 objects\n";
       //            return *this;
       //        }

               Demo1 &&operator-=(Demo1 const &rhs) &&
               {
                   std::cout << "subtracting two Demo1 objects\n";
                   return std::move(*this);
               }

               Demo1 &&operator<<=(Demo1 const &rhs) &&
               {
                   std::cout << "shiftleft on two Demo1 objects\n";
                   return std::move(*this);
               }

               Demo1 &&operator<<=(size_t rhs) &&
               {
                   std::cout << "shiftleft Demo1 object size_t bits\n";
                   return std::move(*this);
               }

               void insert(std::ostream &out) const        // requires friend
               {
                   out << "inerting a Demo1 object\n";
               }

               void extract(std::istream &in)              // requires friend
               {
                   std::cout << "extracting a Demo1 object\n";
               }
       };

       class Demo2: public FBB::BinopsBase<Demo2>
       {
           public:
               void swap(Demo2 &other)
               {}

               Demo2 &&operator+=(Demo2 const &rhs) &&
               {
                   std::cout << "adding two Demo2 objects\n";
                   return std::move(*this);
               }

               Demo2 &operator+=(Demo2 const &rhs) &
               {
                   std::cout << "adding (self-defined) two Demo2 objects";
                   return *this;
               }

               Demo2 &&operator^=(Demo2 const &rhs) &&
               {
                   std::cout << "xor-ing two Demo2 objects\n";
                   return std::move(*this);
               }

               Demo2 &&operator|=(Demo2 const &rhs) &&
               {
                   std::cout << "or-ing two Demo2 objects\n";
                   return std::move(*this);
               }

       };

       int main()
       {
           Demo1 d1a, d1b;
           Demo1 d1c = d1a + d1b;
           d1a += d1b;
           d1c = Demo1{} + d1b;

           std::cout << "Here we are " << d1c << ’\n’;
           std::cin >> d1c;

           d1a <<= d1a;
           d1a <<= 5;

           Demo2 d2a, d2b;
           Demo2 d2c = d2a + d2b;
           d2a ^= d2b;
           d2c = Demo2{} ^ d2b;

           d2c = d2c | d2b;
       }

FILES

       bobcat/binopsbase - defines the binary operator function templates

SEE ALSO

       bobcat/binops(3), bobcat(7)

BUGS

       None Reported.

DISTRIBUTION FILES

       o      bobcat_4.08.02-x.dsc: detached signature;

       o      bobcat_4.08.02-x.tar.gz: source archive;

       o      bobcat_4.08.02-x_i386.changes: change log;

       o      libbobcat1_4.08.02-x_*.deb: debian package holding the libraries;

       o      libbobcat1-dev_4.08.02-x_*.deb: debian package holding the libraries, headers and manual pages;

       o      http://sourceforge.net/projects/bobcat: public archive location;

BOBCAT

       Bobcat is an acronym of `Brokken’s Own Base Classes And Templates’.

COPYRIGHT

       This is free software, distributed under the terms of the GNU General Public License (GPL).

AUTHOR

       Frank B. Brokken (f.b.brokken@rug.nl).