ruby on rails - Why does Object::try work if it's sent to a nil object? -

if try call method on nil object in ruby, nomethoderror exception arises message:

"undefined method ‘...’ nil:nilclass" 

however, there try method in rails return nil if it's sent nil object:

require 'rubygems' require 'active_support/all'  nil.try(:nonexisting_method) # no nomethoderror exception anymore 

so how try work internally in order prevent exception?

activesupport 4.0.0 defines 2 try methods: one object instances:

class object   def try(*a, &b)     if a.empty? && block_given?       yield self     else       public_send(*a, &b) if respond_to?(a.first)     end   end end 

the other nilclass instances (nil objects):

class nilclass   def try(*args)     nil   end end 

now, suppose have object instance (excluding nil, inherits object, else in ruby), defining method returns nil:

class test   def returns_nil     nil   end end 

so, running test.new.try(:returns_nil) or test.new.not_existing_method, object#try called, check if public method exists (the respond_to?); if call method (the public_send), else return nil (there aren't other lines).

if call try on of these returning nil methods:

test.new.try(:returns_nil).try(:any_other_method) test.new.try(:not_existing_method).try(:any_other_method) 

we call nilclass#try, nil#try, ignores , returns nil. other try called on nil instance , return nil.