Tease out Object#acts_like? behaviors

1 files changed, 10 insertions, 0 deletions

diff --git a/activesupport/lib/active_support/core_ext/object/acts_like.rb b/activesupport/lib/active_support/core_ext/object/acts_like.rb
new file mode 100644
index 0000000000..fcc8e50f06
--- /dev/null
+++ b/activesupport/lib/active_support/core_ext/object/acts_like.rb
@@ -0,0 +1,10 @@
+class Object
+  # A duck-type assistant method. For example, Active Support extends Date
+  # to define an acts_like_date? method, and extends Time to define
+  # acts_like_time?. As a result, we can do "x.acts_like?(:time)" and
+  # "x.acts_like?(:date)" to do duck-type-safe comparisons, since classes that
+  # we want to act like Time simply need to define an acts_like_time? method.
+  def acts_like?(duck)
+    respond_to? :"acts_like_#{duck}?"
+  end
+end