Car.h

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#pragma once
 
// gemc
#include "gbase.h"
 
// gfactory
#include "gdl.h"
#include "gfactory_options.h"
 
class Car : public GBase<Car>
{
public:
    ~Car() override = default;
 
    explicit Car(const std::shared_ptr<GOptions>& g) : GBase(g, PLUGIN_LOGGER) {
    }
 
    virtual void go() = 0;
 
    void set_loggers([[ maybe_unused ]] const std::shared_ptr<GOptions>& g) {
    }
 
    double generalCarVar = 44;
 
    // Historical note:
    // The block below shows a previous approach that returned a no-arg factory function. The current example
    // passes GOptions into the factory so the created object can be configured consistently.
 
    static Car* instantiate(const dlhandle h, std::shared_ptr<GOptions> g) {
        if (!h) return nullptr;
 
        // Function pointer type matching the exported extern "C" symbol.
        using fptr = Car* (*)(std::shared_ptr<GOptions>);
 
        // Must match the extern "C" declaration in the derived factories.
        // Symbol resolution uses the POSIX API \c dlsym.
        auto sym = dlsym(h, "CarFactory");
        if (!sym) return nullptr;
 
        // The cast is required because dlsym returns void*.
        // This pattern is common in plugin loaders: resolve symbol -> cast -> call.
        auto func = reinterpret_cast<fptr>(sym);
        return func(g);
    }
};