Question

It is possible to define a method in ... = format like this:

class A
  def f= x
    puts x
  end
end

A.new.f = 5

But is it possible to define a method in this format with arguments so that it can be used like the following?

A.new.f(a, b, c) = 5

Edit

You can do this with []=

class A
  def []= x, y, z
    puts x, y, z
  end
end

A.new[1, 2] = 3

Is this an exceptional case?

Answer 1

A.new.f(a, b, c) = 5

is syntax error, so for sure not (this doesn’t make sense too 😉

[] is just sugar for .send(:[]=, …) which is just setter with fancy name.

You can define setter with multiple arguments, but the only way to use it is by

A.new.send(:f=, "first", "second")

because parser doesn’t allow syntax like A.new.foo = “first”, “second”.