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POC++: use a pure virtual function in a non-virtual function
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  1. POC++: use a pure virtual function in a non-virtual function
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    copied!<p>I'm trying to make a base class that defines the interfaces for all derived classes. </p> <p>I'd like to have a function that allows one to read a config file for that class, which is working out pretty smooth using <code>boost::property_tree</code>. Let's call this function <code>readConfig</code>. This would have to be defined in each derived class, so I made it pure virtual.</p> <p>I would like to overload the <code>readConfig</code> function in the base class where every overloaded function in the base class eventually calls the pure virtual form, e.g.:</p> <pre><code>class Base { // ... void readConfig(string, string); // read config from file virtual void readConfig(boost::property_tree::ptree, string) =0; // read config from ptree } void Base::readConfig(string filename, string entry) { boost::property_tree::ptree pt; read_xml(filename, pt); readConfig(pt, entry); // &lt;= Calling pure virtual function! } </code></pre> <p>Basically the string version is just a quick wrapper for the pure virtual form. When I compile this, I get an error:</p> <pre><code>no known conversion for argument 1 from std::string to boost::property_tree::ptree` </code></pre> <p>So it seems, the nonvirtual function (from <code>Base</code>) is not recognized as being available. I checked that my derived class definition is ok:</p> <pre><code>class Deriv : public Base { // ... void readConfig(boost::property_tree::ptree, string); // implement virtual, error is on this line } void Deriv::readConfig( boost::property_tree::ptree pt, string entry) { //... } </code></pre> <p>note that I omitted a lot of <code>const</code>-correctnes, pass by reference etc. to make the code a bit more readable. </p> <p>What can I do to fix this? Is using a pure virtual member-function in a non-virtual function a good idea?</p>
 

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