Inverting 2 conditionals in one function

Question

I'm not sure if this is the best title to describe what I'm looking to achieve, but I essentially have 2 conditionals:

1. current_file.early?
2. required_file.early?

if current_file.early? && !required_file.early? do
...
end

if !current_file.early? && required_file.early? do
...
end

I think I've been looking at this too long, but I just want to know if there's an easier way for me to simplify this, as they are essentially the inverse of each other. I know I can do a nested if,

current_file.early?
 !required_file.early? && do_something
 required_file.early? && do_something_else

but that's not what I'm looking for either. I'm trying to find something a little more elegant if it exists.

Answer 1

Build a truth table for all the possible conditions as follow:

Horizontal: current_file.early?
Vertical: requited_file.early?

        true    false
true    noop    first
false   second  noop

So there is actually 3 different outcomes: when first condition is true, when second condition is true, otherwise - no operation (noop).

To make your code clear it would be better to define each condition as separate method with meaningful name.

def first_cond?
  current_file.early? && !requited_file.early?
end

def second_cond?
  !current_file.early? && requited_file.early?
end

if first_cond?
  # when first condition
elsif second_cond?
  # when second condition
else
  # noop
end

And yes, there is no shorter nor elegant way to simplify the given pair of conditions (in terms of formal logic and its rules).