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private and protected
this example from a Well House Consultants training course
Source code: current Module: R116
# private and protected
class Train def initialize(length,seats) @length = length @seats = seats end # private means "only without object qualifier" # private # protected means "only in same class or ones that inherit from it protected def getseats() return @length * @seats end # Cancel out ongoing restrictions imposed by previous "private" or "protected" # make the rest public (i.e. return to default permission, which is allow-all) public def getcapacity() # next line FAILS on private because of explicit object being used # but it WORKS if the method called is protected. return (self.getseats * 1.4).to_i # return (getseats * 1.4).to_i # means exactly the same ... works for private too! end def Train.totalpassengers(*choices) so_far = 0 for choice in choices addon = choice.getcapacity so_far += addon end return so_far end end paddington = Train.new(5,78) looe = Train.new(1,73) p paddington.getcapacity p looe.getcapacity overall_capacity = Train.totalpassengers(paddington,looe) puts overall_capacity # Next line will fail at run time - call to protected method from outside class p looe.getseats __END__ munchkin:rpj12 grahamellis$ ruby current 546 102 648 current:47: protected method `getseats' called for #<Train:0x109730c08 @seats=73, @length=1> (NoMethodError) munchkin:rpj12 grahamellis$ Learn about this subject
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