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  4. Checking for empty guid

Checking for empty guid

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  • S Stepan Kobzey

    Thats how one of our developers with 18 years experience checks if guid is empty

    public List GetCommentIdsByUserQueryID_Paging(Guid userQueryID, out int total, int skipCount = 0, int itemsPerPage = 20)
            {
    .........
                 if (userQueryID.ToString().Length==0) return null;
    ..........

    J Offline
    J Offline
    JMK NI
    wrote on last edited by
    #8

    Why doesn't he just generate the same guid again and compare?

    B 1 Reply Last reply
    0
    • OriginalGriffO OriginalGriff

      Sander Rossel wrote:

      I heard it's bugged

      You heard right - it's not even slightly unique.

      Those who fail to learn history are doomed to repeat it. --- George Santayana (December 16, 1863 – September 26, 1952) Those who fail to clear history are doomed to explain it. --- OriginalGriff (February 24, 1959 – ∞)

      Sander RosselS Offline
      Sander RosselS Offline
      Sander Rossel
      wrote on last edited by
      #9

      Isn't a non-unique GUID pretty unique :D

      It's an OO world.

      public class SanderRossel : Lazy<Person>
      {
      public void DoWork()
      {
      throw new NotSupportedException();
      }
      }

      P 1 Reply Last reply
      0
      • P PIEBALDconsult

        What if it has lower-case zeroes? :-D

        You'll never get very far if all you do is follow instructions.

        Sander RosselS Offline
        Sander RosselS Offline
        Sander Rossel
        wrote on last edited by
        #10

        You mean they aren't the letter O?

        It's an OO world.

        public class SanderRossel : Lazy<Person>
        {
        public void DoWork()
        {
        throw new NotSupportedException();
        }
        }

        1 Reply Last reply
        0
        • S Stepan Kobzey

          Thats how one of our developers with 18 years experience checks if guid is empty

          public List GetCommentIdsByUserQueryID_Paging(Guid userQueryID, out int total, int skipCount = 0, int itemsPerPage = 20)
                  {
          .........
                       if (userQueryID.ToString().Length==0) return null;
          ..........

          B Offline
          B Offline
          Bernhard Hiller
          wrote on last edited by
          #11

          Don't fix that! Other places using that function meanwhile rely on its "feature" that it returns a *special* list for Guid.Empty()!

          P 1 Reply Last reply
          0
          • J JMK NI

            Why doesn't he just generate the same guid again and compare?

            B Offline
            B Offline
            Bernhard Hiller
            wrote on last edited by
            #12

            Exactly. Ought to be

            Guid invalid = Guid.Empty();
            if (userQueryID.ToString().ToUpper() != invalid.ToString().ToUpper());return null;

            Oops;! Happened to add another feature...

            P 1 Reply Last reply
            0
            • S Stepan Kobzey

              Thats how one of our developers with 18 years experience checks if guid is empty

              public List GetCommentIdsByUserQueryID_Paging(Guid userQueryID, out int total, int skipCount = 0, int itemsPerPage = 20)
                      {
              .........
                           if (userQueryID.ToString().Length==0) return null;
              ..........

              N Offline
              N Offline
              Nagy Vilmos
              wrote on last edited by
              #13

              IIRC guid's are value not reference types so they can't be empty. Doesn't it have hasValue() method or some such?

              Richard DeemingR 1 Reply Last reply
              0
              • N Nagy Vilmos

                IIRC guid's are value not reference types so they can't be empty. Doesn't it have hasValue() method or some such?

                Richard DeemingR Offline
                Richard DeemingR Offline
                Richard Deeming
                wrote on last edited by
                #14

                They can't be null, but they can be empty, which is the guid equivalent of zero. http://msdn.microsoft.com/en-us/library/system.guid.empty.aspx[^] There's no HasValue property or method; you just need to test whether it's equal to Guid.Empty.


                "These people looked deep within my soul and assigned me a number based on the order in which I joined." - Homer

                "These people looked deep within my soul and assigned me a number based on the order in which I joined" - Homer

                P 1 Reply Last reply
                0
                • Richard DeemingR Richard Deeming

                  They can't be null, but they can be empty, which is the guid equivalent of zero. http://msdn.microsoft.com/en-us/library/system.guid.empty.aspx[^] There's no HasValue property or method; you just need to test whether it's equal to Guid.Empty.


                  "These people looked deep within my soul and assigned me a number based on the order in which I joined." - Homer

                  P Online
                  P Online
                  PIEBALDconsult
                  wrote on last edited by
                  #15

                  Richard Deeming wrote:

                  you just need to test whether it's equal to Guid.Empty

                  Except for that you probably don't actually need to. Edit: I'm also suspicious as to whether or not they're actually using System.Guid. The snippet doesn't specify, so it's possible that they rolled their own Guid class and then all bets are off.

                  You'll never get very far if all you do is follow instructions.

                  Richard DeemingR 1 Reply Last reply
                  0
                  • P PIEBALDconsult

                    Richard Deeming wrote:

                    you just need to test whether it's equal to Guid.Empty

                    Except for that you probably don't actually need to. Edit: I'm also suspicious as to whether or not they're actually using System.Guid. The snippet doesn't specify, so it's possible that they rolled their own Guid class and then all bets are off.

                    You'll never get very far if all you do is follow instructions.

                    Richard DeemingR Offline
                    Richard DeemingR Offline
                    Richard Deeming
                    wrote on last edited by
                    #16

                    Well, you do if you want to know whether or not it's empty. ;P


                    "These people looked deep within my soul and assigned me a number based on the order in which I joined." - Homer

                    "These people looked deep within my soul and assigned me a number based on the order in which I joined" - Homer

                    P 1 Reply Last reply
                    0
                    • Richard DeemingR Richard Deeming

                      Well, you do if you want to know whether or not it's empty. ;P


                      "These people looked deep within my soul and assigned me a number based on the order in which I joined." - Homer

                      P Online
                      P Online
                      PIEBALDconsult
                      wrote on last edited by
                      #17

                      Except you probably don't actually need to.

                      You'll never get very far if all you do is follow instructions.

                      1 Reply Last reply
                      0
                      • Sander RosselS Sander Rossel

                        Isn't a non-unique GUID pretty unique :D

                        It's an OO world.

                        public class SanderRossel : Lazy<Person>
                        {
                        public void DoWork()
                        {
                        throw new NotSupportedException();
                        }
                        }

                        P Online
                        P Online
                        PIEBALDconsult
                        wrote on last edited by
                        #18

                        Pretty much the same argument as that for "there are no uninteresting numbers". :thumbsup: "If there are uninteresting numbers, there must be a first uninteresting number, and that number would therefore be pretty interesting."

                        You'll never get very far if all you do is follow instructions.

                        1 Reply Last reply
                        0
                        • B Bernhard Hiller

                          Exactly. Ought to be

                          Guid invalid = Guid.Empty();
                          if (userQueryID.ToString().ToUpper() != invalid.ToString().ToUpper());return null;

                          Oops;! Happened to add another feature...

                          P Online
                          P Online
                          PIEBALDconsult
                          wrote on last edited by
                          #19

                          Is the errant semi-colon on purpose? :suss:

                          You'll never get very far if all you do is follow instructions.

                          1 Reply Last reply
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                          • B Bernhard Hiller

                            Don't fix that! Other places using that function meanwhile rely on its "feature" that it returns a *special* list for Guid.Empty()!

                            P Online
                            P Online
                            PIEBALDconsult
                            wrote on last edited by
                            #20

                            Bernhard Hiller wrote:

                            it returns a *special* list for Guid.Empty()!

                            It's _expecte_d to, but does it?

                            You'll never get very far if all you do is follow instructions.

                            1 Reply Last reply
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