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Subject: [boost] Interest in bit-wise flags?
From: Jeffrey Bush (jeff_at_[hidden])
Date: 2014-06-17 20:09:05

Hi Boost!

I have developed a type-safe bit-wise flags class for my own personal use
am wondering if it would be of interest for me to submit it as a Boost
At the moment it is not ready for submission (code is messy) but I am
the waters so I present an overview below.
* Fully ISO standard C++11 (except for an MSVC version which is
  except it doesn't support as many an infinite number of flag names)
* They are type-safe, requiring explicit casts to and from integers/booleans
* Supports standard bit-wise operations, and always keep values within the
  possible set of flags
* Supports getting the name of a flag and looking up flags by name at
  (when a flag is actually multiple-flags it gives something like "A|B")
* Supports getting an array of all flags at run-time

Now the bad things, which may be a deal-breaker:
* Because of limitations in C++ the syntax can feel a bit awkward. You have
  use a macro to define flag-names (which actually creates a class) then you
  can pass those flag-names as template arguments to the flags. An example:
    typedef Flags<std::uint8_t, Flag_A, Flag_B, Flag_C>::WithValues<0x01,
0x02, 0x04> MyFlags;
* I also couldn't get around using the ::WithValues nested class
* I use a set of macros to make this cleaner (e.g. the above could be
  FLAGS(A, B, C)) and once defined there is no more ugliness

Thanks for consideration!

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