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POC++. Templates and run time user information
 

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    <p>I've been trying to learn more about generic programming since it's something I think I don't know enough about. So I'm thinking about how I would implement a template version of one of my programs. The program I am trying to do this with is a numerical integrator program in which the user selects which integrator to use (i.e. Euler, Runge Kutta, etc) and then integrates whatever function they choose. My current method of doing this is by having an abstract base class called Integrator, and several derived classes that implement the integration method. So the code would look something like this (much more going on but this is just to show the methodology). Note that I use Qt for this and I declare an Integrator *integrator; in the MainWindow class.</p> <pre><code>void MainWindow::on_integrateButton_clicked() { string whichIntegrator = getUserChoice(); integrator = getIntegrator( whichIntegrator, whichFunction, order ); integrator-&gt;setUp( data ); // things like initial conditions, time, step size, etc... runIntegratorInNewThread(); } </code></pre> <p>with getIntegrator essentially using the factory method</p> <pre><code>// x being current data, xdot being the results of evaluating derivatives typedef void (*pFunction)(const double t, const double x[], double *xdot); Integrator* getIntegrator( const string &amp;whichIntegrator, pFunction whichFunction, int order ) { if (whichIntegrator == "Euler") { return new Euler(whichFunction, order); } else if (whichIntegrator == "RungeKutta") { return new RungeKutta(whichFunction, order); } } </code></pre> <p>So this method works fine, and the integrator program runs very well. Now I know that template functions are generated at compile time and given that I'm using run time information, how would you implement this using templates? If the question is not clear, what I'm asking is... Given a user choice at run time, that being which integrator to use, how do I call the correct integration function using a template method?</p>
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    1. CODon't try to apply templates to random situations. They are extremely useful in certain scenarios, but I don't think this one's one of them. Just keep the dynamic polymorphism using virtual functions if it's working OK.
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    2. COThanks for the reply. I suppose it's that I have seen a few integrator codes, all used templates. The difference with them though was it was more of a 'open the cpp file and edit stuff there to run it', whereas mine is a GUI that has all sorts of bells and whistles. I was just interested to see if this could be templated. My current template use extends as far as writing algorithms for containers and I'm sure I could be using them for more than that. Integration is after all, an algorithm of sorts, so perhaps I could have templated it. Seems better to stick with virtual functions here though.
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