int main() {
    std::puts(xorstr_("an extra long hello_world"));
}

// This macro creates an encrypted xor_string string instance.
#define xorstr(string) xor_string<...>{string}

// For convenience sake there is also a macro to instantly decrypt the string
#define xorstr_(string) xorstr(string).crypt_get()

struct xor_string<CharType, ...> {
    using size_type     = std::size_t;
    using value_type    = CharT;
    using pointer       = value_type*;
    using const_pointer = const value_type*;
    
    // Returns string size in characters, not including null terminator.
    constexpr size_type size() const;
    
    // Runs the encryption/decryption algorithm on the internal storage.
    void crypt() noexcept;
    
    // Returns const pointer to the storage, without doing any modifications to it.
    const_pointer get() const;
    
    // Returns non const pointer to the storage, without doing any modifications to it.
    pointer get();

    // Runs crypt() and returns the pointer to the internal storage.
    pointer crypt_get();
}