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Sample class with accessors and comparator methods
Classes and Objects example from a Well House Consultants training course
More on Classes and Objects [link]
Source code: train.rb Module: R105
about = <<"STUFF" This example defines a class with accessors, some default and some none-default parameters to its constructor. There's also a demonstration of a comparator method that return one of two objects it compares. Below, you'll find a sample program which runs when this class file is called on its own, but is skipped when this file is included in another application - an ideal test harness. STUFF class Train attr_accessor :uclass attr_accessor :nstaff def initialize(ncars,uclass="125",nstaff=3) @length = ncars @uclass = uclass @nstaff = nstaff end def getdftdesiredlength() return @length-1 end def getspc() (@nstaff*1.0)/@length end def betterstaffed(second) # First input - function call # the "self" can be omitted (job protection coding) first_val = self.getspc() # Second input - call the method second_val = second.getspc() # return an OBJECT - not the best ratio # that way - you can report what you want! first_val < second_val ? second : self end end # Test Harness! if __FILE__ == $0 morning = Train.new(2,"150",2) diversion = Train.new(7) evening = Train.new(1,"153",2) # Next line - pretty awful if it expects an int! late = Train.new("Usually 1, sometimes 2") # Following will FAIL - Constructor needs 1 to 3 params # in this case! # ghost = Train.new puts morning.nstaff puts evening.nstaff puts morning.getdftdesiredlength puts evening.getdftdesiredlength puts morning.uclass() puts evening.uclass() puts morning.getspc puts evening.getspc # How to call a comparator in Ruby service1 = morning.betterstaffed(evening) service2 = evening.betterstaffed(morning) # tested both ways to test both bits of logic! print service1.uclass()," - ",service2.uclass(),"\n" end result = <<"EXAMPLE" Sample output: Dorothy:rn grahamellis$ ruby train.rb 2 2 1 0 150 153 1.0 2.0 153 - 153 Dorothy:rn grahamellis$ EXAMPLE Learn about this subject
This module and example are covered on the following public courses:
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