OOP
in [OOP]
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From: Jordan Marr on 4 Apr 2008 11:43 I just took one of those online programming tests (where you have a few minutes to answer each question, multiple choice). One of the OOP questions threw me for a loop. The code sample showed three classes: car, engine and piston. The car 'had an' engine, and the engine 'had a' collection of pistons. Then the car class had a Start() void that delegated work to the engine class, which delegated work to the pistons. None of the three classes had a base class. The question asked what OO concept was being demonstrated in the code sample: delegation, composition, polymorphism, combination, or inheritance. It seemed to me that the answer could be either delegation or composition. Generally, the two go hand in hand, but there was only one "correct" answer. I went with "composition", because it seemed likely to be listed before delegation as an OOP concept. Thoughts? Jordan
From: lbonafide on 4 Apr 2008 13:43 On Apr 4, 11:43 am, Jordan Marr <jnm...(a)hotmail.com> wrote: > I just took one of those online programming tests (where you have a > few minutes to answer each question, multiple choice). One of the OOP > questions threw me for a loop. Was this a Brainbench ("Braindead") test? > > The code sample showed three classes: car, engine and piston. The car > 'had an' engine, and the engine 'had a' collection of pistons. Then > the car class had a Start() void that delegated work to the engine > class, which delegated work to the pistons. None of the three classes > had a base class. > > The question asked what OO concept was being demonstrated in the code > sample: > delegation, composition, polymorphism, combination, or inheritance. > > It seemed to me that the answer could be either delegation or > composition. Generally, the two go hand in hand, but there was only > one "correct" answer. I went with "composition", because it seemed > likely to be listed before delegation as an OOP concept. I think you chose correctly, though I see your point. An example of delegation without composition would be if one of your methods or member functions constructed an object (e.g. a std::string), used it for some task, and then let it go out of scope when the function returned. Anyway, I hate those tests. Was this for a job?
From: H. S. Lahman on 5 Apr 2008 10:00 Responding to Marr... > I just took one of those online programming tests (where you have a > few minutes to answer each question, multiple choice). One of the OOP > questions threw me for a loop. > > The code sample showed three classes: car, engine and piston. The car > 'had an' engine, and the engine 'had a' collection of pistons. Then > the car class had a Start() void that delegated work to the engine > class, which delegated work to the pistons. None of the three classes > had a base class. > > The question asked what OO concept was being demonstrated in the code > sample: > delegation, composition, polymorphism, combination, or inheritance. > > It seemed to me that the answer could be either delegation or > composition. Generally, the two go hand in hand, but there was only > one "correct" answer. I went with "composition", because it seemed > likely to be listed before delegation as an OOP concept. It depends upon whose definition of 'composition' you use. In an OO context it usually refers either: (A) to aggregation through one object being embedded in another's implementation; or (B) to an object's definition being defined (composed) through multiple inheritance. So I would go with delegation. FWIW, I don't like the example. For example, association roles like "had" are very often a symptom of lazy problem space abstraction. Also, at the level of abstraction where Piston is important, Car should probably be collaborating with a StarterMotor rather than Engine. -- There is nothing wrong with me that could not be cured by a capful of Drano. H. S. Lahman hsl(a)pathfindermda.com Pathfinder Solutions http://www.pathfindermda.com blog: http://pathfinderpeople.blogs.com/hslahman "Model-Based Translation: The Next Step in Agile Development". Email info(a)pathfindermda.com for your copy. Pathfinder is hiring: http://www.pathfindermda.com/about_us/careers_pos3.php. (888)OOA-PATH
From: Jordan Marr on 9 Apr 2008 14:55 On Apr 4, 2:43 pm, lbonaf...(a)yahoo.com wrote: > On Apr 4, 11:43 am, Jordan Marr <jnm...(a)hotmail.com> wrote: > > > I just took one of those online programming tests (where you have a > > few minutes to answer each question, multiple choice). One of the OOP > > questions threw me for a loop. > > Was this a Brainbench ("Braindead") test? > > > > > The code sample showed three classes: car, engine and piston. The car > > 'had an' engine, and the engine 'had a' collection of pistons. Then > > the car class had a Start() void that delegated work to the engine > > class, which delegated work to the pistons. None of the three classes > > had a base class. > > > The question asked what OO concept was being demonstrated in the code > > sample: > > delegation, composition, polymorphism, combination, or inheritance. > > > It seemed to me that the answer could be either delegation or > > composition. Generally, the two go hand in hand, but there was only > > one "correct" answer. I went with "composition", because it seemed > > likely to be listed before delegation as an OOP concept. > > I think you chose correctly, though I see your point. An example of > delegation without composition would be if one of your methods or > member functions constructed an object (e.g. a std::string), used it > for some task, and then let it go out of scope when the function > returned. > > Anyway, I hate those tests. Was this for a job? Yes, I had to take a C# test and an ASP.NET test for a job. The employer said I could not be a senior level developer since I graduated in '04 and have 5 years experience with C# / ASP.NET. Nevermind the fact that .Net is only 6 years old, and that my last 4 contract jobs have been senior level positions. I'm not a big fan of timed tests. It's really disconcerting to see the 3 minute javascript timer counting down on each question. Multiply that by 40 questions, and it becomes an anxiety laden 2 hours! Still, I did fairly well. My percentile for C# was 90th, and for asp.net was 98th! Unfortunately, I cannot see which ones I missed. It did list OOP as a strong point though, but I'm sure some of the people in this group could have made some much harder OO questions. :) Jordan
From: Lloyd Bonafide on 9 Apr 2008 18:37 Jordan Marr <jnmarr(a)hotmail.com> wrote in news:58cb29b0-71e0-4ec2-86f2- a3d234666677(a)2g2000hsn.googlegroups.com: > It did list OOP as a > strong point though, but I'm sure some of the people in this group > could have made some much harder OO questions. :) Let me guess: What is polymorphism? What is the difference between inheritance and composition? Those are the ones I usually get. :-)
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