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Comment by Benjamin_Dobell | Hacker News Reader

This is pretty standard practice, in C# too. However, it's still somewhat prone to typos.

If you don't care about backward compatibility (i.e. the flags are used internally and never written anywhere), then a better method is actually to grab the value one line above and bit shift it by one. That way you can insert values in the middle and you won't have to change every single line (just two).

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Yeah, but still there's possibility of failure there as you could paste in and forget to update the one below.

Honestly, flags should be a type. IIRC, the C# designers have admitted this was a mistake on their parts to continue C's ambiguity between flag enums and choice enums.

Crystal has a Flag attribute for enums (Flag enums):

http://crystal-lang.org/docs/syntax_and_semantics/enum.html

Nim supports sets which IMO is a much better solution: http://nim-lang.org/docs/manual.html#types-set-type

Taken from Pascal and other Wirthian languages. Nim actually looks vaguely Wirthish in some areas. Interesting.

Nim's author was originally a Turbo Pascal/Delphi programmer. A lot of Nim and its conventions (things like prefixing type names with T and members with F) come directly from Borland's Pascal dialect.

Ah, so a Set keyed with an Enum is functionally C-style "flags" then?

Pretty much. Here is an example:

    type
      EGlassRNState = enum
        EGlassRNState_Initial,
        EGlassRNState_Weakened,
        EGlassRNState_Shattering,
        EGlassRNState_Shattered,
        EGlassRNState_ActiveFrags

    proc hasGlassShattered(mState: set[EGlassRNState]): bool =
      EGlassRNState_Shattered in mState

    proc hasActiveFragments(mState: set[EGlassRNState]): bool =
      EGlassRNState_ActiveFrags in mState

    assert hasActiveFragments({EGlassRNState_Shattered, EGlassRNState_ActiveFrags})

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