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# frozen_string_literal: true
class Object
# Provides a way to check whether some class acts like some other class based on the existence of
# an appropriately-named marker method.
#
# A class that provides the same interface as <tt>SomeClass</tt> may define a marker method named
# <tt>acts_like_some_class?</tt> to signal its compatibility to callers of
# <tt>acts_like?(:some_class)</tt>.
#
# For example, Active Support extends <tt>Date</tt> to define an <tt>acts_like_date?</tt> method,
# and extends <tt>Time</tt> to define <tt>acts_like_time?</tt>. As a result, developers can call
# <tt>x.acts_like?(:time)</tt> and <tt>x.acts_like?(:date)</tt> to test duck-type compatibility,
# and classes that are able to act like <tt>Time</tt> can also define an <tt>acts_like_time?</tt>
# method to interoperate.
#
# Note that the marker method is only expected to exist. It isn't called, so its body or return
# value are irrelevant.
#
# ==== Example: A class that provides the same interface as <tt>String</tt>
#
# This class may define:
#
# class Stringish
# def acts_like_string?
# end
# end
#
# Then client code can query for duck-type-safeness this way:
#
# Stringish.new.acts_like?(:string) # => true
#
def acts_like?(duck)
case duck
when :time
respond_to? :acts_like_time?
when :date
respond_to? :acts_like_date?
when :string
respond_to? :acts_like_string?
else
respond_to? :"acts_like_#{duck}?"
end
end
end
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84 entries across 80 versions & 12 rubygems