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What does the following code mean in Ruby?
||= Does it have any meaning or reason for the syntax?
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Greater Than(>) operator checks whether the first operand is greater than the second operand. If so, it returns true. Otherwise it returns false. For example, 6>5 will return true.
If a class defines a method named + , for example, then that changes the meaning of abbreviated assignment with += for all instances of that class.
The: or operator has a lower precedence than || . or has a lower precedence than the = assignment operator. and and or have the same precedence, while && has a higher precedence than || .
Triple Equals Operator (More Than Equality) Our last operator today is going to be about the triple equals operator ( === ). This one is also a method, and it appears even in places where you wouldn't expect it to. Ruby is calling the === method here on the class.
a ||= b is a conditional assignment operator. It means:
a is undefined or falsey, then evaluate b and set a to the result.a is defined and evaluates to truthy), then b is not evaluated, and no assignment takes place.For example:
a ||= nil # => nil a ||= 0 # => 0 a ||= 2 # => 0 foo = false # => false foo ||= true # => true foo ||= false # => true Confusingly, it looks similar to other assignment operators (such as +=), but behaves differently.
a += b translates to a = a + b a ||= b roughly translates to a || a = b It is a near-shorthand for a || a = b. The difference is that, when a is undefined, a || a = b would raise NameError, whereas a ||= b sets a to b. This distinction is unimportant if a and b are both local variables, but is significant if either is a getter/setter method of a class.
Further reading:
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