anytype is a small, header-only C++11 library providing a dynamically-typed, memory-safe object wrapper.
Yes, but dynamic_cast is relatively slow and boost::any is a huge dependency. anytype is a small and fast library with an extremely simple interface. anytype has hardly more overhead than a regular heap-allocated object.
No. We do not delete void pointers or violate strict aliasing in any way.
Call .set() to set the anytype value. Call .match<typename>(f) to provide a function f that will be called if the anytype's current type is <typename>. Pass in a function that takes its argument by reference in order to modify the anytype value. match returns *this so calls can be chained. Or, pass in no arguments and match simply returns true/false. Call .value<typename>() to attempt to extract the value of the anytype. Call clear() to delete the stored object.
anytype treats char const* as std::string for convenience. To store a char const*, explicity call set<char const*>("my c string");
See this example:
#include <iostream>
#include <string>
#include "anytype.h"
struct S {
~S() {
std::cout << "S being destructed." << std::endl;
}
};
int main() {
anytype a = "This is a char const*, but anytype turns it into a std::string";
a.match<std::string>([](std::string const&) {
std::cout << "A is a std::string." << std::endl;
});
/* equivalent:
if (a.match<std::string>()) {
std::cout << "A is a std::string." << std::endl;
}
*/
a = new S();
a = 10; // ~S() is called
a = 'A';
a = "a string";
a = 15.8;
a.match<float>([](float i) {
// This will not execute
std::cout << "A is not a float: " << i << std::endl;
}).match<double>([](double& i) {
// This will execute
std::cout << "A is a double: " << i << std::endl;
i += 5;
});
a.value<double>(); // 20.8
a.set<float>(a.value<double>()); // equivalent: a.set(20.8f);
a.match<float>([](float i) {
std::cout << "Now, A is a float: " << i << std::endl;
});
/* equivalent:
if (a.match<float>()) {
std::cout << "Now, A is a float: " << a.value<float>() << std::endl;
}
*/
anytype b = a;
b.match<float>([](float i) {
std::cout << "B is a copy of A: " << i << std::endl;
});
/* redundant - clear() is automatically called when a and b go out of scope.
a.clear();
b.clear();
*/
std::cin.get();
return 0;
}This outputs the following:
A is a std::string.
S being destructed.
A is a double: 15.8
Now, A is a float: 20.8
B is a copy of A: 20.8
anytype can not be directly constructed as a pointer, since passing a pointer to anytype's constructor means anytype is taking ownership of a heap object. To actually have anytype store a pointer, call set with an explicit pointer type, e.g.
anytype a;
a.set<my_class*>(my_class_pointer);Copyright © 2018 Chukwudi Okechukwu
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