enum handling change in VS 2005

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Craig Klementowski - 23 Jul 2004 18:37 GMT

All,

I've installed the VS 2005 Beta 1 and was trying to build our current
product. I get a compile error when enum value is specified with
classname::enumname::enumvalue. Seems the compiler does not want the
enumname there anymore. This was not a problem with any previous versions of
VS. I could not find any help in any of my programming books or in MSDN. Can
anyone explain the reasons to me? Is this behavior to stay?

class CMyEnumClass

{

public:

enum MyMode

{

MM_Mode1,

MM_Mode2,

MM_Mode3,

MM_Mode4

};

};

int _tmain(int argc, _TCHAR* argv[])

{

// CMyEnumClass::MyMode m = CMyEnumClass::MyMode::MM_Mode3;// in VS 2005 -
error C2825: 'CMyEnumClass::MyMode': must be a class or namespace when
followed by '::'

CMyEnumClass::MyMode m2 = CMyEnumClass::MM_Mode3;//ok in ALL

return 0;

}

Thanks!

Craig Klementowski

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Gabest - 23 Jul 2004 20:44 GMT

Actually, I never knew you could include the enum's name in the reference to
the enum, but it seems to be ok for vs2003. However, in my opinion, allowing
this would make the following case legal also, since you can differ which
"something" you want, like s::e1::something or s::e2::something.

struct s
{
enum e1 {something = 1};
enum e2 {something = 2};
};

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Ronald Laeremans [MSFT] - 23 Jul 2004 23:09 GMT

The fact that the VC 7.1 compiler allowed this was a bug that we fixed for
the 2005 version. Enums are not scope qualified according to both the C and
C++ standards.

Ronald Laeremans
Visual C++ team

> All,
>
[quoted text clipped - 46 lines]
>
> Craig Klementowski

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Craig Klementowski - 26 Jul 2004 15:45 GMT

Thanks Ron. I'll get to cleaning up our code then.

Craig

> The fact that the VC 7.1 compiler allowed this was a bug that we fixed for
> the 2005 version. Enums are not scope qualified according to both the C and
[quoted text clipped - 53 lines]
> >
> > Craig Klementowski

Reply to this Message

Ken Durden - 28 Jul 2004 15:55 GMT

> The fact that the VC 7.1 compiler allowed this was a bug that we fixed for
> the 2005 version. Enums are not scope qualified according to both the C and
> C++ standards.
>
> Ronald Laeremans
> Visual C++ team

Ron,

Given all the extensive language extensions provided as part of .NET,
I think it would be a very good idea to leave the enum scope
qualification as a language extension.

Not only does it make MC++ more similar to C#.NET, but it's simply a
good idea on its own regard. Lack of enum scoping frequently forces
name mutilation into the enum fields:

enum EColor
{
eColor_Red,
eColor_Blue,
}

This sucks in any case where you want to use the textual value of the
enum for printout purposes.

Finally, doesn't removing enum scope qualification in MC++ introduce
possibilities where MC++ will be unable to interact with enums defined
in C#.NET? Since C# supports enum scoping, it seems there could be
cases where duplicate enumerared values (potentially with different
meaning or numeric values) are defined in different enum types. C# can
handle this fine, but MC++ cannot?

Thanks,
-ken

Reply to this Message

Ronald Laeremans [MSFT] - 29 Jul 2004 00:19 GMT

Hi Ken,

enum class Foo {... } will act identical to an enum defined in C# or another
CLR language.
enum Foo { ... } will act as per the ANSI/ISO C and C++ standards.

If you want a non managed enum to behave the same it is fairly easy to write
a class in standard C++ that has the scoped behavior and use that instead.

Ronald

>> The fact that the VC 7.1 compiler allowed this was a bug that we fixed
>> for
[quoted text clipped - 33 lines]
> Thanks,
> -ken

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enum handling change in VS 2005

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