多个进程可以写入同一个文件夹吗？(Can multiple processes write to the same folder?)

 如果你可以将枚举提升到编译时常数，那么它是可能的： 
 
template <MessageType E, class Data>
void Send(Data const& ) { ... }
 
 我们可以创建一个类模板，专门针对枚举所期望的每个枚举： 
 
template <MessageType E> struct expected_type;
template <> struct expected_type<MessageType::TypeA> { using type = Foo; };
template <> struct expected_type<MessageType::TypeB> { using type = Bar; };
template <> struct expected_type<MessageType::TypeM> { using type = Foo; };

template <MessageType E>
using expected_type_t = typename expected_type<E>::type;
 
 然后我们可以使用它来编写静态断言： 
 
template <MessageType E, class Data>
void Send(Data const& ) {
    static_assert(std::is_same<Data, expected_type_t<E>>{}, "!");
    // ...
}
 
 或者，可以使用该类模板直接设置Data类型： 
 
template <MessageType E>
void Send(expected_type_t<E> const& ) {
    ...
}

If you can lift the enum to a compile time constant, then it's possible:
 
template <MessageType E, class Data>
void Send(Data const& ) { ... }
 
We can create a class template, specialized on each enum with what that enum expects:
 
template <MessageType E> struct expected_type;
template <> struct expected_type<MessageType::TypeA> { using type = Foo; };
template <> struct expected_type<MessageType::TypeB> { using type = Bar; };
template <> struct expected_type<MessageType::TypeM> { using type = Foo; };

template <MessageType E>
using expected_type_t = typename expected_type<E>::type;
 
And then we can use that to just write that static assert:
 
template <MessageType E, class Data>
void Send(Data const& ) {
    static_assert(std::is_same<Data, expected_type_t<E>>{}, "!");
    // ...
}
 
Alternatively, could use that class template to set the Data type directly:
 
template <MessageType E>
void Send(expected_type_t<E> const& ) {
    ...
}