3.4 KiB
Operator Overloading
Operator overloading is supported, but strongly discouraged. Operator overloading should only be used for types that represent mathematical concepts that users can be reliably expected to understand how they behave with math operators, and for which the implementations are extremely efficient. Operator overloading should not be used to hide expensive computations or to create domain-specific syntax to make certain operations more concise. Examples of good candidates for operator overloading would include:
- Mathematical vectors
- Matrices
- Quaternions
- Complex numbers
Bad candidates would include:
- Arbitrarily sized datastructures
- Objects that represent regular expressions
- Objects that represent filesystem paths
Available Operator Overloads
When performing a math operation between any two types that are not both numerical or boolean, the compiler will look up the appropriate method and insert a function call to that method. Math overload operations are all assumed to return a value that is the same type as the first argument and the second argument must be either the same type as the first argument or a number, depending on the specifications of the specific operator.
Addition
func plus(T, T)->T
The + operator invokes the plus() method, which takes two objects of the
same type and returns a new value of the same type.
Subtraction
func minus(T, T)->T
The - operator invokes the minus() method, which takes two objects of the
same type and returns a new value of the same type.
Multiplication
func times(T, T)->T
The * operator invokes the times() method, which takes two objects of the
same type and returns a new value of the same type. This should not be used
to implement either a dot product or a cross product. Dot products and cross
products should be implemented as explicitly named methods.
func scaled_by(T, N)->T
In a multiplication expression, a*b, if either a or b has type T and
the other has a numeric type N (either Int8, Int16, Int32, Int,
Num32, or Num), then the method scaled_by() will be invoked.
Division
func divided_by(T, N)->T
In a division expression, a/b, if a has type T and b has a numeric
type N, then the method divided_by() will be invoked.
Exponentiation
func power(T, N)->T
In an exponentiation expression, a^b, if a has type T and b has a
numeric type N, then the method power() will be invoked.
Modulus
func mod(T, N)->T
func mod1(T, N)->T
In a modulus expression, a mod b or a mod1 b, if a has type T and b
has a numeric type N, then the method mod() or mod1() will be invoked.
Negative
func negative(T)->T
In a unary negative expression -x, the method negative() will be invoked.
Bit Operations
func left_shift(T, Int)->T
func right_shift(T, Int)->T
func bit_and(T, T)->T
func bit_or(T, T)->T
func bit_xor(T, T)->T
In a bit shifting expression, a >> b or a << b, if a has type T and b
is an Int, then the method left_shift() or right_shift() will be invoked.
In a bitwise binary operation a and b, a or b, or a xor b, then the
method bit_and(), bit_or(), or bit_xor() will be invoked.
Bitwise Negation
func negated(T)->T
In a unary bitwise negation expression not x, the method negated() will be
invoked.