Compile time unique identifier

Would there be anyway for the compiler, or the language, to provide a unique ID during compilation?

I've been using UUID generators, but I've always found the approach of copy pasting from a program to code to be kind of... limiting. If I want a random number, can't the compiler guarantee this for me?

It already does the same thing for anonymous namespaces, so...

Any ideas?

Could you use something involving the __DATE__ and __TIME__ macros?

Yeah, I think the only standard way to do it is __DATE__ and __TIME__ as laserlight suggested. It's not a number though. You can use a regex an sprintf to create a static number out of it though.

Well, __DATE__ and __TIME__ are just numbers that change between each compilation, but they aren't unique within a same cpp.

I'm basically trying to do something like this:

Code:

---

class one
{
  static const int id = COMPILE_TIME_UNIQUE_ID;
};

class two
{
  static const int id = COMPILE_TIME_UNIQUE_ID;
};

---

or

Code:

---

class one : base<COMPILE_TIME_UNIQUE_ID>
{
};

class two : base<COMPILE_TIME_UNIQUE_ID>
{
};

---

but where COMPILE_TIME_UNIQUE_ID is different for both classes.

I'm wondering if maybe using some meta programming way to do it. Maybe something that increments every time it is evaluated?

there's boost preprocessor BOOST_PP_COUNTER/BOOST_PP_UPDATE_COUNTER macros to do that portably. But the resulting ids will be unique across all compilation units only if those classes are included in the same order ...

There's __LINE__ and __COUNTER__ with MSVC.
http://msdn.microsoft.com/en-us/library/b0084kay.aspx

gcc has __COUNTER__ as well.
http://gcc.gnu.org/onlinedocs/cpp/Co...defined-Macros

gg

Thanks for your replies,

I've learned from your links, but I do not think I'll be able to do what I'm trying. No big deal though.