Agree. It's a bad design to use old C++ scoping rules for enum values. Even
C++ itself has introduced enum class in C++11.
在 2015年11月10日星期二 UTC+8上午3:15:35，Teddy Zhang写道：
>
> Sorry to dig this old thread.
> I now one of the solution right now is to put the enum to different proto
> file and put them into different package. But that doesn't really work if
> the enums are under the same message.
>
> I would suggest add an option for c/c++, like below:
> enum Foo {
> option c_enum_prefix = "eFoo";
> FIRST = 0;
> SECOND = 1;
> BOTH = 2;
> }
>
> And it will generate enum like below in c/c++:
> enum Foo {
> eFooFIRST = 0,
> eFooSECOND = 1,
> eFooBOTH = 2
> };
>
> This won't affect enum generation in managed language like java/c#, and it
> won't break backward compatibility (if the option is not specified,
> fallback to old behavior).
>
> Any comments?
>
> On Friday, August 20, 2010 at 11:12:30 AM UTC-7, alopecoid wrote:
>
>> Hi,
>>
>> This post is about the fact that protobuf enum values use C++ scoping
>> rules, meaning that, unlike in Java, enum values are siblings of their
>> type, not children of it.
>>
>> Say I have the following contrived message:
>>
>> message MyMessage {
>> enum Foo {
>> FIRST = 0;
>> SECOND = 1;
>> BOTH = 2;
>> }
>> required Foo foo = 1;
>>
>> enum Bar {
>> FIRST = 0;
>> SECOND = 1;
>> BOTH = 2;
>> }
>> required Bar bar = 2;
>> }
>>
>> This wouldn't compile because the protobuf compiler recognizes the
>> fact that for C++, the generated enum values for Foo and Bar would
>> conflict with each other.
>>
>> However, for Java, this wouldn't be a problem. I would like to propose
>> that instead of "punishing" the generated Java code because of C++'s
>> strange enum behavior (by forcing developers to rename their enum
>> values even though they don't collide), that instead, the generated C+
>> + enum declarations are wrapped in their own nested namespaces? For
>> example, something like:
>>
>> namespace Foo {
>> enum Enum {
>> FIRST = 0;
>> SECOND = 1;
>> BOTH = 2;
>> }
>> }
>>
>> namespace Bar {
>> enum Enum {
>> FIRST = 0;
>> SECOND = 1;
>> BOTH = 2;
>> }
>> }
>>
>> At this point, the enum values would be accessed like Foo::FIRST,
>> Bar::FIRST, etc, which would eliminate the enum value collision
>> problem altogether, and at the same time make them appear to behave
>> more like Java's enum scoping rules (which arguably make more sense).
>>
>> Thoughts?
>>
>> Thank you.
>
>
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