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).