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Dynamically assign values to instance

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csharplinqperformancetutorialquestion
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  • C Calin Tatar

    I think you could try by using Dynamic Invocation. Calin

    S Offline
    S Offline
    Stevo Z
    wrote on last edited by
    #11

    Do you suggest to create a method using reflection on the fly:

    void AssingAValue(AClass aInstance, object value)
    {
    aInstance.AValue = value;
    }

    and then just call this method?

    zilo

    C 1 Reply Last reply
    0
    • S Stevo Z

      Do you suggest to create a method using reflection on the fly:

      void AssingAValue(AClass aInstance, object value)
      {
      aInstance.AValue = value;
      }

      and then just call this method?

      zilo

      C Offline
      C Offline
      Calin Tatar
      wrote on last edited by
      #12

      yes, so you can dynamically change the AValue property. Calin

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      0
      • S Stevo Z

        Yes. I'm loading the class from dll as

        Assembly.LoadFile(string file);

        And I'd like to keep AClass as simple as possible, without any specific code to read or write values into it. It's just a data container.

        zilo

        S Offline
        S Offline
        S Senthil Kumar
        wrote on last edited by
        #13

        Well, LINQ knows the types of data objects at compile time, so there's no similarity there. Without reflection, I guess your best bet is emitting the IL directly[^].

        Regards Senthil [MVP - Visual C#] _____________________________ My Home Page |My Blog | My Articles | My Flickr | WinMacro

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        0
        • S Stevo Z

          Interesting idea, but... It's not only one, there will be many properties like this within AClass. And it needs to be done outside of constructor.

          zilo

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          D Offline
          DaveyM69
          wrote on last edited by
          #14

          Maybe extension methods could work. Create an extension method ToAClass for each type, and also pass the AClass instance.

          public static class ExtensionMethods
          {
          static public void SetAClass(this string value, AClass instance)
          {
          instance.AString = value;
          }

          static public void SetAClass(this int value, AClass instance)
          {
              instance.AInt = value;
          }
          

          }
          public class AClass
          {
          public string AString
          {
          get;
          set;
          }
          public int AInt
          {
          get;
          set;
          }
          }

          AClass aInstance = new AClass();
          "Test string".SetAClass(aInstance);
          123.SetAClass(aInstance);

          Dave
          BTW, in software, hope and pray is not a viable strategy. (Luc Pattyn)
          Visual Basic is not used by normal people so we're not covering it here. (Uncyclopedia)

          S 1 Reply Last reply
          0
          • D DaveyM69

            Maybe extension methods could work. Create an extension method ToAClass for each type, and also pass the AClass instance.

            public static class ExtensionMethods
            {
            static public void SetAClass(this string value, AClass instance)
            {
            instance.AString = value;
            }

            static public void SetAClass(this int value, AClass instance)
            {
                instance.AInt = value;
            }
            

            }
            public class AClass
            {
            public string AString
            {
            get;
            set;
            }
            public int AInt
            {
            get;
            set;
            }
            }

            AClass aInstance = new AClass();
            "Test string".SetAClass(aInstance);
            123.SetAClass(aInstance);

            Dave
            BTW, in software, hope and pray is not a viable strategy. (Luc Pattyn)
            Visual Basic is not used by normal people so we're not covering it here. (Uncyclopedia)

            S Offline
            S Offline
            Stevo Z
            wrote on last edited by
            #15

            Anyhow, whether is it extension methods or not, I'll have to create them dynamically using reflection and then just call those methods. I think I have a better idea now, thanks

            zilo

            1 Reply Last reply
            0
            • S S Senthil Kumar

              Well, LINQ knows the types of data objects at compile time, so there's no similarity there. Without reflection, I guess your best bet is emitting the IL directly[^].

              Regards Senthil [MVP - Visual C#] _____________________________ My Home Page |My Blog | My Articles | My Flickr | WinMacro

              S Offline
              S Offline
              Stevo Z
              wrote on last edited by
              #16

              It doesn't have to, I'm using those classes to work with linq as well and it's working fine. Thanks for the suggestion, that looks to be the only way to go.

              zilo

              S 1 Reply Last reply
              0
              • S Stevo Z

                It doesn't have to, I'm using those classes to work with linq as well and it's working fine. Thanks for the suggestion, that looks to be the only way to go.

                zilo

                S Offline
                S Offline
                S Senthil Kumar
                wrote on last edited by
                #17

                Zilo(svk) wrote:

                I'm using those classes to work with linq as well and it's working fine

                Now I'm curious - can you paste a snippet of code that does that? I can't imagine LINQ working without you specifying the type somewhere (unless it's an anonymous type, of course).

                Regards Senthil [MVP - Visual C#] _____________________________ My Home Page |My Blog | My Articles | My Flickr | WinMacro

                S 1 Reply Last reply
                0
                • S S Senthil Kumar

                  Zilo(svk) wrote:

                  I'm using those classes to work with linq as well and it's working fine

                  Now I'm curious - can you paste a snippet of code that does that? I can't imagine LINQ working without you specifying the type somewhere (unless it's an anonymous type, of course).

                  Regards Senthil [MVP - Visual C#] _____________________________ My Home Page |My Blog | My Articles | My Flickr | WinMacro

                  S Offline
                  S Offline
                  Stevo Z
                  wrote on last edited by
                  #18

                  I ment the classes are not present withing the same solution or assembly when compiling the code. When working with linq, I'm using strong types. This is a sample of one of the classes:

                  [Table(Name = "Books")]
                  public partial class Book : IDALEntity
                  {
                  private int _BookId;
                  private string _Title;
                  private int _Price;
                  private int _PublisherID;

                      public Book()
                      {   }
                  
                      \[Column(Storage = "\_BookId", AutoSync = AutoSync.OnInsert, DbType = "Int NOT NULL", IsPrimaryKey = true)\]
                      public int BookId
                      {
                          get
                          {
                              return this.\_BookId;
                          }
                          set
                          {
                             this.\_BookId = value;                 
                          }
                      }
                  

                  ...
                  }

                  zilo

                  S 1 Reply Last reply
                  0
                  • S Stevo Z

                    I ment the classes are not present withing the same solution or assembly when compiling the code. When working with linq, I'm using strong types. This is a sample of one of the classes:

                    [Table(Name = "Books")]
                    public partial class Book : IDALEntity
                    {
                    private int _BookId;
                    private string _Title;
                    private int _Price;
                    private int _PublisherID;

                        public Book()
                        {   }
                    
                        \[Column(Storage = "\_BookId", AutoSync = AutoSync.OnInsert, DbType = "Int NOT NULL", IsPrimaryKey = true)\]
                        public int BookId
                        {
                            get
                            {
                                return this.\_BookId;
                            }
                            set
                            {
                               this.\_BookId = value;                 
                            }
                        }
                    

                    ...
                    }

                    zilo

                    S Offline
                    S Offline
                    S Senthil Kumar
                    wrote on last edited by
                    #19

                    Well, LINQ uses reflection to read the custom attributes you provide for each property, so that it can map them to database columns. I guess they do it just once and then generate dynamic code to do the actual translation from SQL results to object property assignments.

                    Regards Senthil [MVP - Visual C#] _____________________________ My Home Page |My Blog | My Articles | My Flickr | WinMacro

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                    0
                    • S Stevo Z

                      Kind of. Something that does the job but keeps the speed on same level as direct access.

                      zilo

                      C Offline
                      C Offline
                      Calin Tatar
                      wrote on last edited by
                      #20

                      Also, you can use TypeDescriptor, and PropertyDescriptor. Calin

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