As I have always been taught in logic, the and operator means both values must be true, for the entire statement to be true. If you have many statements chained with and, then any one of them being false should make the whole claim false. In Ruby, however, I ran into this scenario:
horizon_flat = true
one_up_and_down = true
magellan_fell = false
flat_earth_thesis = horizon_flat and one_up_and_down and magellan_fell
puts("Hey ruby, doesn't the horizon look flat?")
puts(horizon_flat) # true
puts("Isn't there only one up and one down?")
puts(one_up_and_down) # true
puts("Did Magellan fall off the earth?")
puts(magellan_fell) # false
puts("Is the earth flat?")
puts(flat_earth_thesis) # true
Strangely, if I just run the statement itself, it returns false correctly puts(horizon_flat and one_up_and_down and magellan_fell) # false
But if I store that statement in a variable, and later call it, the variable outputs true. Why does Ruby think the earth is flat?
While you expect this:
flat_earth_thesis = horizon_flat and one_up_and_down and magellan_fell
To be evaluated as:
flat_earth_thesis = (horizon_flat and one_up_and_down and magellan_fell)
It is instead evaluated as:
(flat_earth_thesis = horizon_flat) and one_up_and_down and magellan_fell
You likely wanted:
flat_earth_thesis = horizon_flat && one_up_and_down && magellan_fell
As noted in comments, review operator precedence.