`-=` (subtract assign) operator

The right-associative, binary infix -= operator decrements it's left-hand operand by the amount given by its right-hand operand.

Usage

variable Integer num = 4;
num -= 1; // decrement num by 1
num -= num; // decrement num by 3

The -= operator is defined as follows:

lhs = lhs.minus(rhs)

except that lhs is evaluated only once.

See the language specification for more details.

The -= operator is polymorphic. The definition of the -= operator depends on the Invertible interface.

The result type of the -= operator is the same as the type of its right hand operand.