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[.net] Bitwise check - best way?

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Started by devronious February 07, 2008 01:27 PM

15 comments, last by devronious 16 years, 2 months ago

devronious

108

Author

February 08, 2008 08:50 AM

Quote:You are only missing one nice feature of .Net, the FlagsAttribute

Super awesome! Didn't know that. I will use that from now on.

Hey, along that subject, what's the difference between [Flags] and [Flags()]? Is there? Or is it just extra typing?

SiCrane,

Holy Crap, how did you figure that out? That's pretty interesting and smart. Thanks. I wonder if a universal one can be made for various different enums? Or if we can somehow custom add our own operator to Visual Studio 2005-2008? Perhaps thru the SDK? Hmmm...

-Devin

SiCrane

11,840

February 08, 2008 09:44 AM

If you really want one for all Enums:

  class Contains {    Contains(Int64 d) { v = d; }    Int64 v;    public static bool operator &(Contains c, Enum d) {      return (c.v & Convert.ToInt64(d)) != 0;    }    public static explicit operator Contains(Enum d) {      return new Contains(Convert.ToInt64(d));    }  }

It's still evil, however.

devronious

108

Author

February 09, 2008 02:25 PM

Cool, I also put in a feature request for something to this effect with a keyword.

[edit]

Quote:It's still evil, however

Ya I would tend to think that is a bit around the corner and down the road and across the bridge thru some towns, and so on :) But still you figured it out which gives merit.

[Edited by - devronious on February 10, 2008 8:25:45 PM]

Nypyren

12,313

February 13, 2008 10:49 PM

Quote:Original post by SiCrane
If you really want one for all Enums:

  class Contains {    Contains(Int64 d) { v = d; }    Int64 v;    public static bool operator &(Contains c, Enum d) {      return (c.v & Convert.ToInt64(d)) != 0;    }    public static explicit operator Contains(Enum d) {      return new Contains(Convert.ToInt64(d));    }  }

It's still evil, however.

You might go the extra mile and make a C# 3.0 extension method on the Enum base class itself. I don't have my tools installed on this machine yet (building a new computer) but it seems like you should be able to make something less "evil" that way.

SiCrane

11,840

February 14, 2008 07:54 AM

I'm not really familiar with C# 3 right now. Could you give an example when you're set up?

Quote:
Cool, I also put in a feature request for something to this effect with a keyword.

Though if you really want something that looks like a keyword:

  public struct Proxy {    internal long v;        public Proxy(long val) {      v = val;    }        public static bool operator >(Proxy p, Enum e) {      return (p.v & Convert.ToInt64(e)) != 0;    }    public static bool operator <(Proxy p, Enum e) {      return (p.v & Convert.ToInt64(e)) != 0;    }  }    struct C {    public static Proxy operator <(Enum e, C c) {      return new Proxy(Convert.ToInt64(e));    }    public static Proxy operator >(Enum e, C c) {      return new Proxy(Convert.ToInt64(e));    }        static C contains = new C();  }  if (this.bufferDataChanged <C.contains> DataType.Vertex) {do this...}  // or  C contains = new C();  if (this.bufferDataChanged <contains> DataType.Vertex) {do this...}

As you may imagine, still evil.

benryves

2,001

February 14, 2008 08:48 AM

A C#3 example could be something like this:

public static class EnumContains {	public static bool Contains(this Enum e, Enum bit) {		return (Convert.ToInt32(e) & Convert.ToInt32(bit)) != 0;	}}

You could then use it like this:

class Program {	[Flags()] 	public enum DataType {		None = 0,		Vertex = 1,		Index = 2,		UV = 4,		XYZ = 8,		Norm = 16	}	static void Main(string[] args) {				var Test = DataType.UV | DataType.Norm;		Console.WriteLine("Test = {0}", Test);		foreach (DataType Bit in Enum.GetValues(typeof(DataType))) {			Console.WriteLine("Test.Contains({0})\t={1}", Bit, Test.Contains(Bit));		}	}}

[Website] [+++ Divide By Cucumber Error. Please Reinstall Universe And Reboot +++]

devronious

108

Author

February 15, 2008 08:12 PM

Thanks guys, really interesting to see the different solutions to the same problem. Goes to show how programming is so broad and open.

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