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  4. Read-only properties

Read-only properties

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  • P PIEBALDconsult

    I just found a bunch of properties made read-only like this (I think they're from a template):

    set
    {
    // Do nothing
    }

    Huh? If you want it to be read-only, make it read-only! :mad:

    B Offline
    B Offline
    BadKarma
    wrote on last edited by
    #7

    Still, its better then the following

    private int m_iData;
    public int Data
    {
     get 
     {
      return m_iData;
     }
     set
     {
       // store the old data
       //
       int iOldData = m_iData;
    
       m_iData = value;
    
       // reset to old data because its read-only
       //
       m_iData = iOldData
     }
    }
    

    codito ergo sum

    CPalliniC K F 3 Replies Last reply
    0
    • P PIEBALDconsult

      I just found a bunch of properties made read-only like this (I think they're from a template):

      set
      {
      // Do nothing
      }

      Huh? If you want it to be read-only, make it read-only! :mad:

      M Offline
      M Offline
      mav northwind
      wrote on last edited by
      #8

      You guys are so negative! Try to see the good in this approach. Using this approach one could perform consistency checks before not saving the value... :laugh:

      Regards, mav -- Black holes are the places where God divided by 0...

      G P 2 Replies Last reply
      0
      • B BadKarma

        Still, its better then the following

        private int m_iData;
        public int Data
        {
         get 
         {
          return m_iData;
         }
         set
         {
           // store the old data
           //
           int iOldData = m_iData;
        
           m_iData = value;
        
           // reset to old data because its read-only
           //
           m_iData = iOldData
         }
        }
        

        codito ergo sum

        CPalliniC Offline
        CPalliniC Offline
        CPallini
        wrote on last edited by
        #9

        :laugh:

        If the Lord God Almighty had consulted me before embarking upon the Creation, I would have recommended something simpler. -- Alfonso the Wise, 13th Century King of Castile.
        This is going on my arrogant assumptions. You may have a superb reason why I'm completely wrong. -- Iain Clarke

        In testa che avete, signor di Ceprano?

        1 Reply Last reply
        0
        • P PIEBALDconsult

          Yes, but silently ignoring the value is poor style.

          P Offline
          P Offline
          Paul Conrad
          wrote on last edited by
          #10

          PIEBALDconsult wrote:

          silently ignoring the value is poor style.

          Yes, it is. I can only imagine the headache of trying to track it down on a Friday afternoon.

          "The clue train passed his station without stopping." - John Simmons / outlaw programmer

          D 1 Reply Last reply
          0
          • M mav northwind

            You guys are so negative! Try to see the good in this approach. Using this approach one could perform consistency checks before not saving the value... :laugh:

            Regards, mav -- Black holes are the places where God divided by 0...

            G Offline
            G Offline
            GibbleCH
            wrote on last edited by
            #11

            Alternately, if at some point in time, the property was to become (or maybe was in the past) not 'readonly', applications relying on the dll wouldn't necessarily need to be recompiled to use the new dll, since the definition wouldn't change...on that item.

            L 1 Reply Last reply
            0
            • B BadKarma

              Still, its better then the following

              private int m_iData;
              public int Data
              {
               get 
               {
                return m_iData;
               }
               set
               {
                 // store the old data
                 //
                 int iOldData = m_iData;
              
                 m_iData = value;
              
                 // reset to old data because its read-only
                 //
                 m_iData = iOldData
               }
              }
              

              codito ergo sum

              K Offline
              K Offline
              Krirk
              wrote on last edited by
              #12

              Excellent code.A guy who wrote this code is genius. :omg: :wtf:X|

              My blog

              1 Reply Last reply
              0
              • G GibbleCH

                Alternately, if at some point in time, the property was to become (or maybe was in the past) not 'readonly', applications relying on the dll wouldn't necessarily need to be recompiled to use the new dll, since the definition wouldn't change...on that item.

                L Offline
                L Offline
                Lutoslaw
                wrote on last edited by
                #13

                Yeach. And if some library user tried to write to a property and didn't notice that it took no effect, then after an upgrade his code could break because the old do-nothing setter would suddenly change something. :doh:

                Greetings - Gajatko Portable.NET is part of DotGNU, a project to build a complete Free Software replacement for .NET - a system that truly belongs to the developers.

                1 Reply Last reply
                0
                • P PIEBALDconsult

                  I just found a bunch of properties made read-only like this (I think they're from a template):

                  set
                  {
                  // Do nothing
                  }

                  Huh? If you want it to be read-only, make it read-only! :mad:

                  L Offline
                  L Offline
                  leppie
                  wrote on last edited by
                  #14

                  You need this scenario with XML deserialization.

                  xacc.ide - now with IronScheme support
                  IronScheme - 1.0 alpha 2 out now

                  P G 2 Replies Last reply
                  0
                  • L leppie

                    You need this scenario with XML deserialization.

                    xacc.ide - now with IronScheme support
                    IronScheme - 1.0 alpha 2 out now

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

                    Good point, but... Not if it's done right. I haven't done much serialization (XML or otherwise), but as I recall the class specifies which members get serialized and deserialized, so this shouldn't be a problem. You might have to override the base class' deserializer. Or I may just be showing my ignorance. :-O

                    L 1 Reply Last reply
                    0
                    • P Paul Conrad

                      PIEBALDconsult wrote:

                      silently ignoring the value is poor style.

                      Yes, it is. I can only imagine the headache of trying to track it down on a Friday afternoon.

                      "The clue train passed his station without stopping." - John Simmons / outlaw programmer

                      D Offline
                      D Offline
                      Derek Bartram
                      wrote on last edited by
                      #16

                      Well, personally I say get rid of properties anyway! There is simply no point in them other than making the language more bloated and less clear.... In the good old days.... .name = public class variable, didn't run any code, just gave access.... now will it run code, or won't it!?!?!??!?

                      P 1 Reply Last reply
                      0
                      • D Derek Bartram

                        Well, personally I say get rid of properties anyway! There is simply no point in them other than making the language more bloated and less clear.... In the good old days.... .name = public class variable, didn't run any code, just gave access.... now will it run code, or won't it!?!?!??!?

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

                        Sure they can be abused, but I wouldn't get rid of them just because of that.

                        D 1 Reply Last reply
                        0
                        • P PIEBALDconsult

                          Sure they can be abused, but I wouldn't get rid of them just because of that.

                          D Offline
                          D Offline
                          Derek Bartram
                          wrote on last edited by
                          #18

                          Maybe, but it just seams like a lazy way of coding that means it's harder to tell what code is actually doing. Personally I feel it makes using other people's code harder (particularily badly written code where the property name is misleading)

                          G 1 Reply Last reply
                          0
                          • D Derek Bartram

                            Maybe, but it just seams like a lazy way of coding that means it's harder to tell what code is actually doing. Personally I feel it makes using other people's code harder (particularily badly written code where the property name is misleading)

                            G Offline
                            G Offline
                            GibbleCH
                            wrote on last edited by
                            #19

                            But properly written properties do data validation, and will modify any other values that need to be modified when that property changes.

                            D 1 Reply Last reply
                            0
                            • L leppie

                              You need this scenario with XML deserialization.

                              xacc.ide - now with IronScheme support
                              IronScheme - 1.0 alpha 2 out now

                              G Offline
                              G Offline
                              GibbleCH
                              wrote on last edited by
                              #20

                              THAT'S IT! That's why I had to do something similar to this coding horror.

                              1 Reply Last reply
                              0
                              • G GibbleCH

                                But properly written properties do data validation, and will modify any other values that need to be modified when that property changes.

                                D Offline
                                D Offline
                                Derek Bartram
                                wrote on last edited by
                                #21

                                That's the problem though... the amount of people who i've seen doing things like modify data structures in property gets, is pretty high. Why leave elements of the language that can result in really hard to debug code and misconceptions?

                                G J 2 Replies Last reply
                                0
                                • D Derek Bartram

                                  That's the problem though... the amount of people who i've seen doing things like modify data structures in property gets, is pretty high. Why leave elements of the language that can result in really hard to debug code and misconceptions?

                                  G Offline
                                  G Offline
                                  GibbleCH
                                  wrote on last edited by
                                  #22

                                  But, often, if you don't modify the data of the class, when you set the property, your data may be invalid...and calling functionX at that time will result in invalid results, or errors.

                                  D 1 Reply Last reply
                                  0
                                  • P PIEBALDconsult

                                    Good point, but... Not if it's done right. I haven't done much serialization (XML or otherwise), but as I recall the class specifies which members get serialized and deserialized, so this shouldn't be a problem. You might have to override the base class' deserializer. Or I may just be showing my ignorance. :-O

                                    L Offline
                                    L Offline
                                    leppie
                                    wrote on last edited by
                                    #23

                                    PIEBALDconsult wrote:

                                    I recall the class specifies which members get serialized and deserialized, so this shouldn't be a problem.

                                    Sometimes you want only readonly properties in XML serialization. Unfortunately for de/serialization to work, properties need to have both a getter and a setter.

                                    xacc.ide - now with IronScheme support
                                    IronScheme - 1.0 alpha 2 out now

                                    P 2 Replies Last reply
                                    0
                                    • L leppie

                                      PIEBALDconsult wrote:

                                      I recall the class specifies which members get serialized and deserialized, so this shouldn't be a problem.

                                      Sometimes you want only readonly properties in XML serialization. Unfortunately for de/serialization to work, properties need to have both a getter and a setter.

                                      xacc.ide - now with IronScheme support
                                      IronScheme - 1.0 alpha 2 out now

                                      P Offline
                                      P Offline
                                      PIEBALDconsult
                                      wrote on last edited by
                                      #24

                                      The set accessor should then be private. However, the base class' contract may not allow that and then you're stuck.

                                      L 1 Reply Last reply
                                      0
                                      • G GibbleCH

                                        But, often, if you don't modify the data of the class, when you set the property, your data may be invalid...and calling functionX at that time will result in invalid results, or errors.

                                        D Offline
                                        D Offline
                                        Derek Bartram
                                        wrote on last edited by
                                        #25

                                        Yes, but it leads to misconceptions about what the code does. I suppose it all comes down to good code documentation perhaps

                                        1 Reply Last reply
                                        0
                                        • P PIEBALDconsult

                                          The set accessor should then be private. However, the base class' contract may not allow that and then you're stuck.

                                          L Offline
                                          L Offline
                                          leppie
                                          wrote on last edited by
                                          #26

                                          PIEBALDconsult wrote:

                                          The set accessor should then be private.

                                          No Xml serialization (I am getting tired typing that!) will choke on that. Just try it!

                                          xacc.ide - now with IronScheme support
                                          IronScheme - 1.0 alpha 2 out now

                                          P 2 Replies Last reply
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