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Comment by Pxtl | Hacker News Reader

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.

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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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