ryuken
Fuchsia
- Joined
- Jun 10, 2024
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this is a challenge to the guy who calls himself technoboss i never saw you actually talk about programming or tech so how do you call yourself techno"boss"
the challenge is:
i want you to tell me the Lambda Functions, Type Traits and Templates and SFINAE of the following c++ code
the punishment if you fail: we will call you lil techno for a week
if you succeeded: i will make my banner whatever you want and i will make an apology thread and give my loyalty to you to the rest of my life
the challenge is:
i want you to tell me the Lambda Functions, Type Traits and Templates and SFINAE of the following c++ code
#include <iostream>
#include <type_traits>
// Primary template for the trait, by default it returns false
template <typename, typename T>
struct has_to_string : std::false_type {};
// Specialization of the trait where substitution will succeed if the class T has a method `std::string to_string() const`
template <typename C>
struct has_to_string<C, std::string(C::*)() const> : std::true_type {};
// Helper template to deduce the function signature
template <typename C>
constexpr bool has_to_string_v = has_to_string<C, decltype(&C::to_string)>::value;
// Example classes
struct A {
std::string to_string() const { return "Class A"; }
};
struct B {
int to_string() const { return 42; } // Different return type, won't match std::string
};
struct C {
void foo() const {} // No `to_string` method at all
};
// Function that uses SFINAE to conditionally compile based on whether the class has a `to_string` method
template <typename T>
typename std::enable_if<has_to_string_v<T>, void>::type
print_to_string(const T& obj) {
std::cout << obj.to_string() << std::endl;
}
template <typename T>
typename std::enable_if<!has_to_string_v<T>, void>::type
print_to_string(const T&) {
std::cout << "No to_string method available" << std::endl;
}
int main() {
A a;
B b;
C c;
print_to_string(a); // Prints "Class A"
print_to_string(b); // Prints "No to_string method available"
print_to_string(c); // Prints "No to_string method available"
return 0;
}
#include <type_traits>
// Primary template for the trait, by default it returns false
template <typename, typename T>
struct has_to_string : std::false_type {};
// Specialization of the trait where substitution will succeed if the class T has a method `std::string to_string() const`
template <typename C>
struct has_to_string<C, std::string(C::*)() const> : std::true_type {};
// Helper template to deduce the function signature
template <typename C>
constexpr bool has_to_string_v = has_to_string<C, decltype(&C::to_string)>::value;
// Example classes
struct A {
std::string to_string() const { return "Class A"; }
};
struct B {
int to_string() const { return 42; } // Different return type, won't match std::string
};
struct C {
void foo() const {} // No `to_string` method at all
};
// Function that uses SFINAE to conditionally compile based on whether the class has a `to_string` method
template <typename T>
typename std::enable_if<has_to_string_v<T>, void>::type
print_to_string(const T& obj) {
std::cout << obj.to_string() << std::endl;
}
template <typename T>
typename std::enable_if<!has_to_string_v<T>, void>::type
print_to_string(const T&) {
std::cout << "No to_string method available" << std::endl;
}
int main() {
A a;
B b;
C c;
print_to_string(a); // Prints "Class A"
print_to_string(b); // Prints "No to_string method available"
print_to_string(c); // Prints "No to_string method available"
return 0;
}
the punishment if you fail: we will call you lil techno for a week
if you succeeded: i will make my banner whatever you want and i will make an apology thread and give my loyalty to you to the rest of my life
