Hi, Griffin On Sat, 13 Aug 2011 04:34:39 -0700 Griffin Howlett <griff.howl@gmail.com> wrote:
Hey, so I'm using the boost::serialization library, and I'm trying to override how a class is constructed, since it has no default constructor. This is demonstrated here<http://www.boost.org/doc/libs/1_47_0/libs/serialization/doc/serialization.html#constructors>. To me it appears the function ONLY takes the `class* t` and then sets it to point to a newly constructed object. If I'm wrong, this is definitely the source of my error.
However, the only way to construct my class is by using another classes `create()` function, meaning I need to stray from the code in the example (this is stated in the boost::serialization namespace): `::new(t)my_class(attribute);`
I believe that the load_construct_data's typical usecase is below. template <class Archive> inline void load_construct_data(Archive& ar, T* t, unsigned int const /*version*/) { AttributeType* attribute; ar >> attribute; ::new(t) T(attribute); }
I tried simply calling the create function and setting `t` equal to the returned pointer, but this doesn't seem to work because right after the `load_construct_data function`, and in the `serialization function`, the given `myClass&` is not the same as what I set 't' to.
Though you overwrite the `t`, it is no effect to load_construct_data's caller. Because the `t` is *copy* of a pointer.
*How do I do whatever ::new(t) is doing so the object created using the create function follows through into the serialize/other functions?*
Why do you want to create my_class from another class? Perhaps custom you want to use custom allocated memory? See boost/archive/detail/iserializer.hpp:246 (Version1.47) struct has_new_operator { static T* invoke() { return static_cast<T *>((T::operator new)(sizeof(T))); } }; The serialization library provide the function that calls your custom operator new. You can provide custom operator new like that. struct my_class { static void* operator new (size_t size) { return another_class::allocate(size); } static void operator delete(void* p) { another_class::deallocate(p); } }; Your custom new/delete operator would be called from the serialization library. If your reason is not custom allocator, you can provide the my_class's constructor that can call from load_construct_data instead of another class's create function. Thanks, Takatoshi