自作複合型に対する演算子オーバーロード

20200915_0648.jl

module Coordinate

    export Rect2d

    mutable struct Rect2d{T} 
        x :: T
        y :: T
    end

    function Base.:+(coordinate_left::Rect2d{T}, coordinate_right::Rect2d{T}) where T <: Core.Number
        return Rect2d(coordinate_left.x + coordinate_right.x, coordinate_left.y + coordinate_right.y)
    end

    function Base.:*(scalar_left::T, coordinate_right::Rect2d{T}) where T <: Core.Number
        return Rect2d(scalar_left * coordinate_right.x, scalar_left * coordinate_right.y)
    end

    function Base.:*(coordinate_left::Rect2d{T}, scalar_right::T) where T <: Core.Number
        return Rect2d(coordinate_left.x * scalar_right, coordinate_left.y * scalar_right)
    end

    function Base.:(==)(coordinate_left::Rect2d, coordinate_right::Rect2d)
        return (coordinate_left.x == coordinate_right.x) && (coordinate_left.y == coordinate_right.y)
    end

    function test_coordinate()
        
        coordinate_a = Rect2d( 1.0, 0.0 )
        coordinate_b = Rect2d( 0.0, 1.0 )
        coordinate_c = coordinate_a + coordinate_b

        Base.@assert coordinate_a + coordinate_b == coordinate_c

        coordinate_a = Rect2d( 1.0, 2.0 )
        coordinate_b = 2.0 * coordinate_a
        coordinate_c = coordinate_a * 2.0
        coordinate_d = Rect2d( 2.0, 4.0 )

        Base.@assert coordinate_b == coordinate_d
        Base.@assert coordinate_c == coordinate_d

    end

end

README.md

reference

1. How to overload the ==? - Usage - JuliaLang