Constness

The use of the const keyword in C++ is not always clear. You


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might not realise that const Something* declares a pointer to a const Something, The pointer can be changed, but not the Something that it points to.

Therefore, the RefPtr equivalent of Something* for a method parameter is const Glib::RefPtr<Something>&, and the equivalent of const Something* is const Glib::RefPtr<const Something>&.

The const ... & around both is just for efficiency, like using const std::string& instead of std::string for a method parameter to