binopsbase(3bobcat)            Binary Operators            binopsbase(3bobcat)



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.

BOBCAT PROJECT FILES
       o      https://fbb-git.gitlab.io/bobcat/: gitlab project page;

       o      bobcat_6.02.02-x.dsc: detached signature;

       o      bobcat_6.02.02-x.tar.gz: source archive;

       o      bobcat_6.02.02-x_i386.changes: change log;

       o      libbobcat1_6.02.02-x_*.deb: debian package containing the
              libraries;

       o      libbobcat1-dev_6.02.02-x_*.deb: debian package containing the
              libraries, headers and manual pages;


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).

libbobcat-dev_6.02.02              2005-2022               binopsbase(3bobcat)