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Direct access to object variable (attributes) in Ruby

Rather than writing getters and setters, in many Object Oriented languages you can access the variables within an object directly. That can be dangerous for code flexibility for the future, as it means that you're removing the possibility of interspersing code. However, it can be very convenient.

In Java, you'll mark members you want publicly visible as public; in Ruby you specify attr_accessor (for read and write variables) and attr_reader for read only variables. There's an example [here].

If you try to access an object variable for which you have not set up an appropriate accessor in Ruby, an exception will be thrown (I've put that into the example too!)
(written 2010-02-02)

 
Associated topics are indexed as below, or enter http://melksh.am/nnnn for individual articles
R108 - Ruby - More Classes and Objects
  [4551] Testing your new class - first steps with cucumber - (2015-10-23)
  [4550] Build up classes into applications sharing data types in Ruby - (2015-10-23)
  [4504] Where does Ruby load modules from, and how to load from current directory - (2015-06-03)
  [4366] Changing what operators do on objects - a comparison across different programming languages - (2014-12-26)
  [3782] Standard methods available on all objects in Ruby - (2012-06-23)
  [3781] Private, Protected, Public in Ruby. What about interfaces and abstract classes in Ruby? - (2012-06-23)
  [3760] Why you should use objects even for short data manipulation programs in Ruby - (2012-06-10)
  [3260] Ruby - a training example that puts many language elements together to demonstrate the whole - (2011-04-23)
  [3158] Ruby training - some fresh examples for string handling applications - (2011-02-05)
  [3154] Changing a class later on - Ruby - (2011-02-02)
  [3142] Private and Public - and things between - (2011-01-22)
  [2980] Ruby - examples of regular expressions, inheritance and polymorphism - (2010-10-02)
  [2977] What is a factory method and why use one? - Example in Ruby - (2010-09-30)
  [2717] The Multiple Inheritance Conundrum, interfaces and mixins - (2010-04-11)
  [2623] Object Oriented Ruby - new examples - (2010-02-03)
  [2616] Defining a static method - Java, Python and Ruby - (2010-02-01)
  [2604] Tips for writing a test program (Ruby / Python / Java) - (2010-01-29)
  [2603] Ruby objects - a primer - (2010-01-29)
  [2601] Ruby - is_a? v instance_of? - what is the difference? - (2010-01-27)
  [2292] Object Orientation in Ruby - intermediate examples - (2009-07-16)
  [1587] Some Ruby programming examples from our course - (2008-03-21)
  [1217] What are factory and singleton classes? - (2007-06-04)
  [656] Think about your design even if you don't use full UML - (2006-03-24)
  [184] MTBF of coffee machines - (2005-01-20)

R111 - Ruby - Exceptions.
  [4675] Exceptions in Ruby - throwing, catching and using - (2016-05-17)
  [4008] Reading and checking user inputs - first lessons - Ruby - (2013-02-17)
  [3435] Sorta sorting a hash, and what if an exception is NOT thrown - Ruby - (2011-09-12)
  [3433] Exceptions - a fail-safe way of trapping things that may go wrong - (2011-09-11)
  [3177] Insurance against any errors - Volcanoes and Python - (2011-02-19)
  [2622] Handling unusual and error conditions - exceptions - (2010-02-03)
  [2621] Ruby collections and strings - some new examples - (2010-02-03)
  [2615] String to number conversion with error trapping in Ruby - (2010-02-01)
  [1875] What are exceptions - Python based answer - (2008-11-08)


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