gistfile1.txt

class A                                                                                                                                                                                                 
  def foo                                                                                                                                                                                               
    raise "error from old"                                                                                                                                                                              
  end                                                                                                                                                                                                   
end                                                                                                                                                                                                     
                                                                                                                                                                                                        
class A                                                                                                                                                                                                 
  def new_foo                                                                                                                                                                                           
    raise "error from new method"                                                                                                                                                                       
  end                                                                                                                                                                                                   
  alias_method :old_foo, :foo                                                                                                                                                                           
  alias_method :foo, :new_foo                                                                                                                                                                           
end                                                                                                                                                                                                     
                                                                                                                                                                                                        
                                                                                                                                                                                                        
begin                                                                                                                                                                                                   
  A.new.foo                                                                                                                                                                                             
rescue => e                                                                                                                                                                                             
  puts e.backtrace.join("\n") # => stack trace from the new method                                                                                                                                      
end                                                                                                                                                                                                     
                                                                                                                                                                                                        
class A                                                                                                                                                                                                 
  alias_method :foo, :old_foo                                                                                                                                                                           
end                                                                                                                                                                                                     
                                                                                                                                                                                                        
begin                                                                                                                                                                                                   
  A.new.foo                                                                                                                                                                                             
rescue => e                                                                                                                                                                                             
  puts e.backtrace.join("\n") # => stack trace from the old method                                                                                                                                      
end