try that try

lib/motion_support/core_ext/object/try.rb

@@ -0,0 +1,2 @@
+require 'bubble-wrap/loader'
+BubbleWrap.require('motion/core_ext/object/try.rb')

motion/core_ext/object/try.rb

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+class Object
+  # Invokes the public method identified by the symbol +method+, passing it any arguments
+  # and/or the block specified, just like the regular Ruby <tt>Object#public_send</tt> does.
+  #
+  # *Unlike* that method however, a +NoMethodError+ exception will *not* be raised
+  # and +nil+ will be returned instead, if the receiving object is a +nil+ object or NilClass.
+  #
+  # If try is called without a method to call, it will yield any given block with the object.
+  #
+  # Please also note that +try+ is defined on +Object+, therefore it won't work with
+  # subclasses of +BasicObject+. For example, using try with +SimpleDelegator+ will
+  # delegate +try+ to target instead of calling it on delegator itself.
+  #
+  # Without +try+
+  #   @person && @person.name
+  # or
+  #   @person ? @person.name : nil
+  #
+  # With +try+
+  #   @person.try(:name)
+  #
+  # +try+ also accepts arguments and/or a block, for the method it is trying
+  #   Person.try(:find, 1)
+  #   @people.try(:collect) {|p| p.name}
+  #
+  # Without a method argument try will yield to the block unless the receiver is nil.
+  #   @person.try { |p| "#{p.first_name} #{p.last_name}" }
+  #
+  # +try+ behaves like +Object#public_send+, unless called on +NilClass+.
+  def try(*a, &b)
+    if a.empty? && block_given?
+      yield self
+    else
+      public_send(*a, &b)
+    end
+  end
+end
+
+class NilClass
+  # Calling +try+ on +nil+ always returns +nil+.
+  # It becomes specially helpful when navigating through associations that may return +nil+.
+  #
+  #   nil.try(:name) # => nil
+  #
+  # Without +try+
+  #   @person && !@person.children.blank? && @person.children.first.name
+  #
+  # With +try+
+  #   @person.try(:children).try(:first).try(:name)
+  def try(*args)
+    nil
+  end
+end
+
+

spec/core_ext/object/try_spec.rb

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+describe "ObjectTry"do
+  before do
+    @string = "Hello"
+  end
+
+  it "nonexisting method" do
+    method = :undefined_method
+    @string.respond_to?(method).should.not == true
+    lambda{  @string.try(method)}.should.raise(NoMethodError)
+  end
+
+  it "nonexisting method with arguments" do
+    method = :undefined_method
+    @string.respond_to?(method).should.not == true
+    lambda{ @string.try(method, 'llo', 'y') }.should.raise(NoMethodError)
+  end
+
+  it "valid method" do
+    @string.try(:size).should == 5
+  end
+
+  it "argument forwarding" do
+     @string.try(:sub, 'llo', 'y').should.equal("Hey")
+  end
+
+  it "block forwarding" do
+    @string.try(:sub, 'llo') { |match| 'y' }.should.equal("Hey")
+  end
+
+  it "nil to type" do
+    nil.try(:to_s).should == nil
+    nil.try(:to_i).should == nil
+  end
+
+  it "false try" do
+    false.try(:to_s).should == 'false'
+  end
+
+  it "try only block" do
+    @string.try { |s| s.reverse }.should == @string.reverse
+  end
+
+  it "try only block nil" do
+    ran = false
+    nil.try { ran = true }
+    ran.should == false
+  end
+
+  it "try with private method" do
+    klass = Class.new do
+      private
+
+      def private_method
+        'private method'
+      end
+    end
+
+    lambda{ klass.new.try(:private_method) }.should.raise(NoMethodError)
+  end
+end