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-----Original Message----- That's what I feel. The error message indicate that the compiler somehow considers "id" and __LINE__ two identifier when the error occurs. I tried using the /P parameter to dump the preprocessed source, and that looked fine, though. So I guess it is the problem with MSVC compiler mixing preprocessing and parsing phases together...

Yes. There is nothing that the pp-lib can do about it.

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What do you mean by "certain scope"? Or, more precisely, given a > finite scope such as that defined by a function, why do you need > unique identifiers? Most of the time when people want unique > identifiers, they want an identifier that is unique across an entire > program or, at minimum, inside a translation unit.

Well... The scope can be the whole program, or in a namespace, or in a translation unit. The unique ID is used in a macro in the library for some tidious code that can be automatically generated using preprocessor.

For the record, doing this sort of thing is almost guaranteed to

I agree. But I pointed this out after much effort trying to debug the mysterious bug. Maybe it'd be better to document this in pp-lib's manual as "known issues?" That'd make future victims' lives easier. :) produce ODR

violations. With that said...

Well... I think I know what I'm doing now. The use of __LINE__ (or __COUNTER__ on MSVC) is working for me after combining with some salt as keyword. Thanks for your concern, but the current solution seems suffice for me purpose.

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Anyway, thanks for Stewart Tootill's suggestion. I had to resort to using __COUNTER__ at the meantime, which seemed working so far. (But one thing that worries me is that __COUNTER__ is only unique within a translation unit. So what if I need a unique identifier throughout the program?)

The pp-lib contains a similar construct, but it must be manually updated. E.g. #include BOOST_PP_UPDATE_COUNTER() BOOST_PP_COUNTER() // 1 #include BOOST_PP_UPDATE_COUNTER() BOOST_PP_COUNTER() // 2 BOOST_PP_COUNTER() // 2 #include BOOST_PP_UPDATE_COUNTER() BOOST_PP_COUNTER() // 3

But this is not documented. :( I didn't know its existence until you told me and then I did a grep.)

I could provide the means to seed this value for a translation unit, but I'm not sure if this is really a good idea. Thoughts?

I don't think there is a general solution for "all cases" here. (At least I don't have one with me right now.) But given some restricted usage, this solution actually works out quite well. BTW, I think I'm still sticking to __LINE__/__COUNTER__ solution for now, since it is not possible for me to encode the "#include ..." line into my macro.

Regards, Paul Mensonides

Thanks a lot for your efforts and insight! Cheers, Freddie