#define constexpr in C ++

Question

我遇到了一些代码，如下所示：

#define set_opcode(name) \
    constexpr static auto get_opcode() noexcept \
    { \
        return OpcodeValue::name; \ //OpcodeValue is some enum
    }

class NoopOpcode : public Opcode
{
public:
    set_opcode(NOOP);

    std::string serialize() const noexcept override;

    bool deserialize(const std::string &serialized) noexcept override;

    void execute(state::State &state) const noexcept override;

};


class InvOpcode : public Opcode
{

private:

    Int _item_id{};

    Int _item_count{};



public:

    set_opcode(INV);

    std::string serialize() const noexcept override;

    bool deserialize(const std::string &serialized) noexcept override;

    void execute(state::State &state) const noexcept override;

};

使用#define声明constexpr的原因/好处是什么？

与明确声明get_opcode（）{return OpcodeValue :: NOOP;例如，在NoopOpcode类中？