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What inherent advantages do boost::any and boost::any_cast offer over using void* and dynamic_cast?
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Why do we use a void pointer in C programs? We use the void pointers to overcome the issue of assigning separate values to different data types in a program. The pointer to void can be used in generic functions in C because it is capable of pointing to any data type.
You can not increment a void pointer. Since a void* is typeless, the compiler can not increment it and thus this does not happen.
A void pointer is a pointer to incomplete type, so if either or both operands are void pointers, your code is not valid C. Note that GCC has a non-standard extension which allows void pointer arithmetic, by treating void pointers as pointer-to-byte for such cases.
The advantage is that boost::any is way more type-safe than void*.
E.g.
int i = 5;
void* p = &i;
static_cast<double*>(p); //Compiler doesn't complain. Undefined Behavior.
boost::any a;
a = i;
boost::any_cast<double>(a); //throws, which is good
As to your comment, you cannot dynamic_cast from a void*. You can dynamic_cast only from pointers and references to class types which have at least one virtual function (aka polymorphic types)
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