hump Helper Utilities for More Productivity

Arithmetic (+, -, *, /) and comparative operators (==, <=, <) are defined:

• + and - only work on vectors. - is also the unary minus (e.g. print(-vector(1,2)) -- prints (-1,-2))
• a * b works on vectors and numbers:
  • If a is a number and b is a vector (or vice versa), the result the scalar multiplication.
  • If a and b both are vectors, then the result is the dot product.
• a / b is only defined for a being a vector and b being a number. Same as a * 1/b.

<= and < sort lexically, i.e. a < b is true if it holds: a.x < b.x or a.y < b.y if a.x == b.x

Warning: This will change the state of all references to this vector.

Warning: This will change the state of all references to this vector.

super's constructor can be accessed via super.construct(self). See example below.

Feline = Class{name = "Feline", function(self, size, weight)
    self.size = size self.weight = weight
end}

function Feline:stats()
    return string.format("size: %.02f, weight %.02f", self.size, self.weight) 
end

function Feline:speak() print("meow") end


Cat = Class{name = "Cat", function(self, name, size, weight)
    Feline.construct(self, size, weight)
    self.name = name
end}
Inherit(Cat, Feline)

function Cat:stats()
    return string.format("name: %s, %s", self.name, Feline.stats(self))
end


Tiger = Class{name = "tiger", function(self, size, weight)
    Feline.construct(self, size, weight)
end}
Inherit(Tiger, Feline)

function Tiger:speak() print("ROAR!") end

felix = Cat("Felix", .8, 12)
hobbes = Tiger(2.2, 68)

print(felix:stats(), hobbes:stats())
felix:speak()
hobbes:speak()

Be careful when using metamethods like __add or __mul: When subclass inherits those methods from a superclass, but does not overwrite them, the result of the operation may be of the type superclass. Consider the following:

A = Class(function(self, x) self.x = x end)
function A:__add(other) return A(self.x + other.x) end
function A:print() print("A:", self.x) end

B = Class(function(self, x, y) A.construct(self, x) self.y = y end)
Inherit(B, A)
function B:print() print("B:", self.x, self.y) end
function B:foo() print("foo") end

one, two = B(1,2), B(3,4)
result = one + two
result:print()  -- prints "A:    4"
result:foo()    -- error: method does not exist