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POReducing parent-child class code duplication
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12153695
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2012-08-28T06:15:55.437
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2013-12-07T19:34:48.947
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2012-08-28T09:39:13.020
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text
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I'm having a problem with polymorphism and parent-child relationships. Take the following two classes, and imagine in my application I create an object of 'child'. Outside of the objects, the only function I call is update(), which in turn invokes everything else I need within the object. The only function in this sequence of calls that differs in 'parent' and 'child' is dosomething2(). <pre><code>class parent { public: void dosomething1() {}; //amongst other things, calls dosomething2 void dosomething2() {}; void update() {}; //amongst other things, calls dosomething1 } class child : public parent { void dosomething2() {} } </code></pre> I realized that if I create an object of 'child' and call update(), only the parent class functions will be called. I had to copy update() and dosomething1() to the child class, and then everything worked as expected. That's not a very nice solution though because there is a lot of duplicate code - is there a way to improve this? UPDATE: Thanks to the answers provided, I updated the parent class with a virtual dosomething2() function. Now the correct function is invoked, and I don't have to copy dosomething1() to the child class. Unfortunately, if I do not copy update() to the child class, I get a symbol lookup error (both parent and child are in a library together). <pre><code>class parent { public: void dosomething1() {}; //amongst other things, calls dosomething2 virtual void dosomething2() {}; void update() {}; //amongst other things, calls dosomething1 } class child : public parent { void dosomething2() {} /*void update() {}; //symbol lookup error if this is left uncommented */ } </code></pre> UPDATE2 The symbol lookup error was not related to the code. I did a make clean, and then make (which builds a .so library and the executable) and now things work as expected.
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Reducing parent-child class code duplication
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