What does &. (ampersand dot) mean in Ruby?

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It is called the Safe Navigation Operator. Introduced in Ruby 2.3.0, it lets you call methods on objects without worrying that the object may be nil(Avoiding an undefined method for nil:NilClass error), similar to the try method in Rails.

So you can write

@person&.spouse&.name

instead of

@person.spouse.name if @person && @person.spouse

From the Docs:

my_object.my_method

This sends the my_method message to my_object. Any
object can be a receiver but depending on the method’s visibility
sending a message may raise a NoMethodError.

You may use &. to designate a receiver, then my_method is not invoked
and the result is nil when the receiver is nil. In that case, the
arguments of my_method are not evaluated.

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