Operators

CliPP also allows you full operator support. You can overload almost all C++ operators.
 

    class point : public object {
    public:
	//construction
	point(double x,double y,double z);

	//operators
	point& operator=(const point& point1);
	double operator[](int index); //index=0,1,2 returns x_,y_ or z.
	vector operator-(const point& point1); //Returns the distance between two points
	bool operator!() //Returns true if position lies in origo
	//operations
	...
	//access
	...
    private:
	double x_,y_,z_;
    }; 

Some of the above operators might be rather artificial, but they are useful in illustrating how to expose operators to CliPP:

    cls[self = self];	//assignment
    cls[self[int()]];	//subscript access
    cls[self - self); 	//subtraction
    cls[!self]; 		//not

In the example above, self is used to indicate the class you want to expose. it is required that self is one of the arguments in the expression.
There are four different types of operators:

binary operators

Operators with two arguments that do not change the content of any of its arguments.

• LHS argument will be transferred  as const lhsT&
• RHS argument will be transferred  as const rhsT&

Example of binary operators include

• additive                  (+,-)
• multiplicative        (*,/,%)
• shift operations     (<<,>>)
• comparison            (==,!=,>,>=,<,<=)
• bitwise                    (&,|,^)

In C++ these operators can be written as

    friend operator op(const point& lhs,const point& rhs);
    friend operator op(const point& lhs,const vector& rhs);
    friend operator op(const vector& lhs,const point& rhs);

where op is replaced with the correct operator from the list above.
In CliPP the above operators will be exposed to the class point as:

    cls[self op self];
    cls[self op other<vector>()];
    cls[other<vector>() op self];

The other<T> template When exposing an operator, you use self to indicate the class being exposed. If you have an operator involving another type, you need to give this type in as an argument. You can do this by constructing a dummy-variable of the correct type, as in the subscript example above: self[int()] This is very handy if the type has a default constructor such as int, but breaks down for complex types with no default constructors. This is why the other<T> template exists. It is a helper template that propagates the type supplied to other without constructing an object of that type.

binary inplace operators and assignment

Operators with two arguments that changes the content of its first argument.

• LHS argument will be transferred  as lhsT&
• RHS argument will be transferred  as const rhsT&

Example of binary inplace operators include

• additive                  (+=,-=)
• multiplicative        (*=,/=,%=)
• shift operations     (<<=,>>=)
• bitwise                    (&=,|=,^=)
• assignment            (=)

In C++ these operators can be written as

    point& point::operator op(const point& rhs);
    point& point::operator op(const vector& rhs);

where op is replaced with the correct operator from the list above.
In CliPP the above operators will be exposed to the class point as:

    cls[self op self];
    cls[self op other<vector>()];

unary operators

Operators with one arguments.

• LHS argument will be transferred  as const lhsT&

Example of binary inplace operators include

• +,-,!,~,++,--

In C++ these operators can be written as

    point& point::operator op();

where op is replaced with the correct operator from the list above.
In CliPP the above operators will be exposed to the class point as:

    cls[op self];

other operators

• postfix operators (++,--)
• subscript operator( []) (only subscripts with 1 argument supported)

In C++ these operators can be written as

    point& point::operator ++(int);
    point& point::operator --(int);
    double point::operator [](int);

In CliPP the above operators will be exposed to the class point as:

    cls[self++];
    cls[self--];
    cls[self[int()]];

Copyright © 2003-2005 Peder Holt

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