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  4. Which is more usefull Abstract Class or Interface and Why?

Which is more usefull Abstract Class or Interface and Why?

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  • D David1987

    Ok, well, please find it :) This is rather odd so I'd prefer to get to the bottom of it

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    Pete OHanlon
    wrote on last edited by
    #11

    It could be that Anders said that while the underlying framework would support it, they made it so that the CLI inhibited it. I'm operating off an old memory here (I probably read this about 8 years ago).

    I'm not a stalker, I just know things. Oh by the way, you're out of milk.

    Forgive your enemies - it messes with their heads

    My blog | My articles | MoXAML PowerToys | Onyx

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    • P Pete OHanlon

      Until I can find the citation, I've struck through the section.

      I'm not a stalker, I just know things. Oh by the way, you're out of milk.

      Forgive your enemies - it messes with their heads

      My blog | My articles | MoXAML PowerToys | Onyx

      W Offline
      W Offline
      Wayne Gaylard
      wrote on last edited by
      #12

      I tried this in CIL :

      .assembly extern mscorlib
      {
      .publickeytoken = (B7 7A 5C 56 19 34 E0 89)
      .ver 4:0:0:0
      }

      .assembly CILTypes
      {
      .ver 1:0:0:0
      }

      .module CILTypes.dll

      .namespace MyCompany
      {
      .namespace MyNameSpace
      {
      .class public interface IMyInterface {}

      .class public MyBaseClass
      {
      }
      
      .class public MyAnotherBaseClass
      {
      }
      
      .class public MyDerivedClass
        extends MyCompany.MyNameSpace.MyBaseClass
        extends MyCompany.MyNameSpace.MyNotherBaseClass
        implements MyCompany.MyNameSpace.IMyInterface
      {
      }
      

      }
      }

      and the compiler throws this error MyBaseClass.il(30) : error : syntax error at token 'extends' in : extends myCompany.MyNameSpace.MyBaseClass. So I guess it would be a restriction on all .Net languages.

      ...and I have extensive experience writing computer code, including OIC, BTW, BRB, IMHO, LMAO, ROFL, TTYL.....

      P 1 Reply Last reply
      0
      • W Wayne Gaylard

        I tried this in CIL :

        .assembly extern mscorlib
        {
        .publickeytoken = (B7 7A 5C 56 19 34 E0 89)
        .ver 4:0:0:0
        }

        .assembly CILTypes
        {
        .ver 1:0:0:0
        }

        .module CILTypes.dll

        .namespace MyCompany
        {
        .namespace MyNameSpace
        {
        .class public interface IMyInterface {}

        .class public MyBaseClass
        {
        }
        
        .class public MyAnotherBaseClass
        {
        }
        
        .class public MyDerivedClass
          extends MyCompany.MyNameSpace.MyBaseClass
          extends MyCompany.MyNameSpace.MyNotherBaseClass
          implements MyCompany.MyNameSpace.IMyInterface
        {
        }
        

        }
        }

        and the compiler throws this error MyBaseClass.il(30) : error : syntax error at token 'extends' in : extends myCompany.MyNameSpace.MyBaseClass. So I guess it would be a restriction on all .Net languages.

        ...and I have extensive experience writing computer code, including OIC, BTW, BRB, IMHO, LMAO, ROFL, TTYL.....

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        P Offline
        Pete OHanlon
        wrote on last edited by
        #13

        As I just said, it could be that Anders said that they imposed this restriction in the CLI. He definitely said that they could extend it to do it if they had to, but he saw no compelling reason to do so, and about a thousand arguments against. Once I find the interview, I'll post the link.

        I'm not a stalker, I just know things. Oh by the way, you're out of milk.

        Forgive your enemies - it messes with their heads

        My blog | My articles | MoXAML PowerToys | Onyx

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        • P Prasanta_Prince

          In programming point of view Which is more usefull Abstract Class or Interface and Why?

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          PIEBALDconsult
          wrote on last edited by
          #14

          If I could have only one, I'd pick interface. I won't tell you why.

          L K 2 Replies Last reply
          0
          • P PIEBALDconsult

            If I could have only one, I'd pick interface. I won't tell you why.

            L Offline
            L Offline
            Luc Pattyn
            wrote on last edited by
            #15

            PIEBALDconsult wrote:

            I won't tell you why

            Let me guess, you're a concrete guy. :)

            Luc Pattyn [Forum Guidelines] [My Articles] Nil Volentibus Arduum

            Please use <PRE> tags for code snippets, they preserve indentation, improve readability, and make me actually look at the code.

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            • P Prasanta_Prince

              In programming point of view Which is more usefull Abstract Class or Interface and Why?

              L Offline
              L Offline
              Luc Pattyn
              wrote on last edited by
              #16

              You can answer that yourself; just take an existing app that uses both, then try and rewrite it once without using abstract classes, and once without using interfaces. I trust you will never forget the conclusions. :)

              Luc Pattyn [Forum Guidelines] [My Articles] Nil Volentibus Arduum

              Please use <PRE> tags for code snippets, they preserve indentation, improve readability, and make me actually look at the code.

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              • P Prasanta_Prince

                In programming point of view Which is more usefull Abstract Class or Interface and Why?

                K Offline
                K Offline
                Keith Barrow
                wrote on last edited by
                #17

                Tell your lecturer from me that is an imbicile question. It is like saying which is fruitiest, apples or oranges. Both are useful, both have a specific job to do.

                Sort of a cross between Lawrence of Arabia and Dilbert.[^]
                -Or-
                A Dead ringer for Kate Winslett[^]

                P 1 Reply Last reply
                0
                • P PIEBALDconsult

                  If I could have only one, I'd pick interface. I won't tell you why.

                  K Offline
                  K Offline
                  Keith Barrow
                  wrote on last edited by
                  #18

                  :laugh: Me too, but I won't say why either!

                  Sort of a cross between Lawrence of Arabia and Dilbert.[^]
                  -Or-
                  A Dead ringer for Kate Winslett[^]

                  1 Reply Last reply
                  0
                  • K Keith Barrow

                    Tell your lecturer from me that is an imbicile question. It is like saying which is fruitiest, apples or oranges. Both are useful, both have a specific job to do.

                    Sort of a cross between Lawrence of Arabia and Dilbert.[^]
                    -Or-
                    A Dead ringer for Kate Winslett[^]

                    P Offline
                    P Offline
                    Pete OHanlon
                    wrote on last edited by
                    #19

                    Plums. There are just some times when you have to say plums.

                    I'm not a stalker, I just know things. Oh by the way, you're out of milk.

                    Forgive your enemies - it messes with their heads

                    My blog | My articles | MoXAML PowerToys | Onyx

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                    • P Pete OHanlon

                      This really smells like a homework question to me. A way to think about it. An interface is a contract. It states that your class will have certain elements, but it puts no constraints on how they will be achieved. An abstract class defines some common functionality that you can override and extend as appropriate. With an interface, you can cast an object to the interface (providing it implements it), and call the functionality on it. This is how IDisposable works with the using statement. Effectively, the following code

                      (using Myclass c = new Myclass())
                      {
                      }

                      translates to

                      Myclass c = null;
                      try
                      {
                      }
                      finally
                      {
                      ((IDisposable)c).Dispose();
                      }

                      Now, you said "In programming", so there's an additional consideration to take into account. In C#, you cannot have multiple inheritance (where you can in C++). What you can do in C# though, is support multiple interface implementation, so your class can inherit from one class but you can implement many interfaces. You note that I said, in C#, there. There's a common misconception that you can't do multiple inheritance in .NET. That's not true. The constraint is put in place by the language, and not the runtime, so if a .NET language chose to allow multiple inheritance, that would be supported. Until I can find the citation for this, please disregard this statement (it's from a very old interview, so it's taking me some time to find it).

                      I'm not a stalker, I just know things. Oh by the way, you're out of milk.

                      Forgive your enemies - it messes with their heads

                      My blog | My articles | MoXAML PowerToys | Onyx

                      modified on Thursday, April 14, 2011 8:22 AM

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                      Prasanta_Prince
                      wrote on last edited by
                      #20

                      Good one..

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