namespace simgrid {
namespace xbt {
+/** A Facetable is an object that you can extend with external facets.
+ *
+ * Facets are similar to the concept of mixins, that is, a set of behavior that is injected into a class without derivation.
+ *
+ * Imagine that you want to write a plugin dealing with the energy in SimGrid.
+ * You will have to store some information about each and every host.
+ *
+ * You could modify the Host class directly (but your code will soon become messy).
+ * You could create a class EnergyHost deriving Host, but it is not easily combinable
+ * with a notion of Host extended with another concept (such as mobility).
+ * You could completely externalize these data with an associative map Host->EnergyHost.
+ * It would work, provided that you implement this classical feature correctly (and it would induce a little performance penalty).
+ * Instead, you should add a new facet to the Host class, that happens to be Facetable.
+ *
+ */
+
template<class T>
-class Lib {
+class Facetable {
private:
static std::vector<void(*)(void*)> deleters_;
protected:
{
return add_level([](void* p){ delete (U*)p; });
}
- Lib() : facets_(deleters_.size(), nullptr) {}
- ~Lib()
+ Facetable() : facets_(deleters_.size(), nullptr) {}
+ ~Facetable()
{
for (std::size_t i = 0; i < facets_.size(); ++i)
if (facets_[i] != nullptr)
};
template<class T>
-std::vector<void(*)(void*)> Lib<T>::deleters_ = {};
+std::vector<void(*)(void*)> Facetable<T>::deleters_ = {};
}
}
