Patch `Delegator` to work with `#try`

`Delegator` inherits from `BasicObject`, which means that it will not
have `Object#try` defined. It will then delegate the call to the
underlying object, which will not (necessarily) respond to the method
defined in the enclosing `Delegator`.

This patches `Delegator` with the `#try` method to work around the
surprising behaviour.

Fixes #5790

1 files changed, 57 insertions, 17 deletions

diff --git a/activesupport/lib/active_support/core_ext/object/try.rb b/activesupport/lib/active_support/core_ext/object/try.rb
index e0f70b9caa..6605771d90 100644
--- a/activesupport/lib/active_support/core_ext/object/try.rb
+++ b/activesupport/lib/active_support/core_ext/object/try.rb
@@ -1,4 +1,36 @@
+require 'delegate'
+
+module ActiveSupport
+  module Try #:nodoc:
+    def try(*a, &b)
+      try!(*a, &b) if a.empty? || respond_to?(a.first)
+    end
+
+    def try!(*a, &b)
+      if a.empty? && block_given?
+        if b.arity.zero?
+          instance_eval(&b)
+        else
+          yield self
+        end
+      else
+        public_send(*a, &b)
+      end
+    end
+  end
+end
+
+[Object, Delegator].each do |klass|
+  klass.include(ActiveSupport::Try)
+end
+
 class Object
+  ##
+  # :method: try
+  #
+  # :call-seq:
+  #   try(*a, &b)
+  #
   # Invokes the public method whose name goes as first argument just like
   # +public_send+ does, except that if the receiver does not respond to it the
   # call returns +nil+ rather than raising an exception.
@@ -56,30 +88,38 @@ class Object
   #
   # Please also note that +try+ is defined on +Object+. Therefore, it won't work
   # with instances of classes that do not have +Object+ among their ancestors,
-  # like direct subclasses of +BasicObject+. For example, using +try+ with
-  # +SimpleDelegator+ will delegate +try+ to the target instead of calling it on
-  # the delegator itself.
-  def try(*a, &b)
-    try!(*a, &b) if a.empty? || respond_to?(a.first)
-  end
+  # like direct subclasses of +BasicObject+.
 
+  ##
+  # :method: try!
+  #
+  # :call-seq:
+  #   try!(*a, &b)
+  #
   # Same as #try, but raises a NoMethodError exception if the receiver is
   # not +nil+ and does not implement the tried method.
   #
   #   "a".try!(:upcase) # => "A"
   #   nil.try!(:upcase) # => nil
   #   123.try!(:upcase) # => NoMethodError: undefined method `upcase' for 123:Fixnum
-  def try!(*a, &b)
-    if a.empty? && block_given?
-      if b.arity.zero?
-        instance_eval(&b)
-      else
-        yield self
-      end
-    else
-      public_send(*a, &b)
-    end
-  end
+end
+
+class Delegator
+  ##
+  # :method: try
+  #
+  # :call-seq:
+  #   try(a*, &b)
+  #
+  # See Object#try
+
+  ##
+  # :method: try!
+  #
+  # :call-seq:
+  #   try!(a*, &b)
+  #
+  # See Object#try!
 end
 
 class NilClass