David Bolen wrote:
thmpsn....@gmail.com writes:
I don't know how you would do it in C# (or Java for that matter).
In C++ you can play with pointers to "get at" some memory location
somewhere in the object. The only portable way to know the exact
location between the beginning of the object and the desired member is
the offsetof() macro, but as I understand it this only works for POD
types, which means that it won't work for classes such as:
class NonPOD
{
private:
int a;
int b;
public:
NonPOD();
~NonPOD();
int C();
};
(I haven't ever actually tried it, so I'm not sure.)
Nevertheless, you can play and hope for the best. For example, if the
member you want to get at is 'b', then you can do:
NonPOD obj;
std::cout << "obj.b = " << *(int*) ((unsigned char*) &obj + sizeof
(int)) << std::endl;
and hope that the compiler didn't leave a hole between the 'a' member
and the 'b' member.
Probably moving off topic, but I don't think you have to get anywhere
near that extreme in terms of pointers, unless you're trying to deal
with instances for which you have no source but only opaque pointers.
I haven't gotten stuck having to do this myself yet, but I believe one
commmon "hack" for the sort of class you show above is to just
"#define private public" before including the header file containing
the class definition. No fiddling with pointers, offsets, or
whatever, just normal object access syntax past that point.
Of course, I believe such a redefinition violates the letter of the
C++ standard, but most preprocessors do it anyway. Also, it won't
handle the case where the "private:" is not used, but the members are
just declared prior to any other definition, since a class is private
by default.
[snip]
You can also "#define class struct" before including the header file.
The only difference between 'class' and 'struct' in C++ is that the
members of a class are private by default and the members of a struct
are public by default.
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