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  4. Checking for empty guid

Checking for empty guid

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  • 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
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            • 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 Offline
              P Offline
              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 Offline
                  P Offline
                  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.

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                  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 Offline
                    P Offline
                    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 Offline
                      P Offline
                      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
                      0
                      • 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 Offline
                        P Offline
                        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.

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