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Dynamically assign values to instance

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  • S Stevo Z

    Hi Guys, I'd like to dynamically assign values to a known class instance based on the Property name. An example describes perfectly what I want to do: There is a class

    public class AClass
    {
    public string _aValue;

        public string AValue
        {
            get { return \_aValue; }
            set { \_aValue = value; }
        }
    }
    

    and I want to assing value to AClass.AValue without actually explicitly writing:

    AClass aInstance = new AClass();
    aInstance.AValue = "value";

    and now comes the best part. I'd like to avoid reflection as much as possible, because performance matters. I could go and look for a property named "AValue" and do

    typeof(AClass).GetProperty("AValue").SetValue(aInstance, "value", null);

    however that's veery slow. It's got to be possible to do that some other way, Linq works like this and it's not slow. any ideas?

    zilo

    M Offline
    M Offline
    musefan
    wrote on last edited by
    #2

    Could try creating a method in the class that takes param name and value, then do a switch and assign the value to the property required

    If only MySelf.Visible was more than just a getter... A person can produce over 5 times there own body weight in excrement each year... please re-read your questions before posting

    S 1 Reply Last reply
    0
    • M musefan

      Could try creating a method in the class that takes param name and value, then do a switch and assign the value to the property required

      If only MySelf.Visible was more than just a getter... A person can produce over 5 times there own body weight in excrement each year... please re-read your questions before posting

      S Offline
      S Offline
      Stevo Z
      wrote on last edited by
      #3

      thanks for the idea, for now something like that is my workaround solution. However I wanted to avoid writing special code into the AClass itself as well. I was thinking of something generic that could either AClass inherit from or a Wrapper class.

      zilo

      1 Reply Last reply
      0
      • S Stevo Z

        Hi Guys, I'd like to dynamically assign values to a known class instance based on the Property name. An example describes perfectly what I want to do: There is a class

        public class AClass
        {
        public string _aValue;

            public string AValue
            {
                get { return \_aValue; }
                set { \_aValue = value; }
            }
        }
        

        and I want to assing value to AClass.AValue without actually explicitly writing:

        AClass aInstance = new AClass();
        aInstance.AValue = "value";

        and now comes the best part. I'd like to avoid reflection as much as possible, because performance matters. I could go and look for a property named "AValue" and do

        typeof(AClass).GetProperty("AValue").SetValue(aInstance, "value", null);

        however that's veery slow. It's got to be possible to do that some other way, Linq works like this and it's not slow. any ideas?

        zilo

        D Offline
        D Offline
        DaveyM69
        wrote on last edited by
        #4

        If it's only the one property you could use an implicit operator overload.

        public class AClass
        {
        public AClass() : this(string.Empty) { }
        private AClass(string aValue)
        {
        AValue = aValue;
        }
        public static implicit operator AClass(string aValue)
        {
        return new AClass(aValue);
        }
        public string AValue
        {
        get;
        set;
        }
        }

        AClass aInstance = "Test String";
        Console.WriteLine(aInstance.AValue);

        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
        • S Stevo Z

          Hi Guys, I'd like to dynamically assign values to a known class instance based on the Property name. An example describes perfectly what I want to do: There is a class

          public class AClass
          {
          public string _aValue;

              public string AValue
              {
                  get { return \_aValue; }
                  set { \_aValue = value; }
              }
          }
          

          and I want to assing value to AClass.AValue without actually explicitly writing:

          AClass aInstance = new AClass();
          aInstance.AValue = "value";

          and now comes the best part. I'd like to avoid reflection as much as possible, because performance matters. I could go and look for a property named "AValue" and do

          typeof(AClass).GetProperty("AValue").SetValue(aInstance, "value", null);

          however that's veery slow. It's got to be possible to do that some other way, Linq works like this and it's not slow. any ideas?

          zilo

          S Offline
          S Offline
          S Senthil Kumar
          wrote on last edited by
          #5

          Zilo(svk) wrote:

          and I want to assing value to AClass.AValue without actually explicitly writing

          It's difficult to answer without knowing why. Is it because you don't know the type at compile time?

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

          S 1 Reply Last reply
          0
          • D DaveyM69

            If it's only the one property you could use an implicit operator overload.

            public class AClass
            {
            public AClass() : this(string.Empty) { }
            private AClass(string aValue)
            {
            AValue = aValue;
            }
            public static implicit operator AClass(string aValue)
            {
            return new AClass(aValue);
            }
            public string AValue
            {
            get;
            set;
            }
            }

            AClass aInstance = "Test String";
            Console.WriteLine(aInstance.AValue);

            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
            #6

            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

            D 1 Reply Last reply
            0
            • S S Senthil Kumar

              Zilo(svk) wrote:

              and I want to assing value to AClass.AValue without actually explicitly writing

              It's difficult to answer without knowing why. Is it because you don't know the type at compile time?

              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
              #7

              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 1 Reply Last reply
              0
              • S Stevo Z

                Hi Guys, I'd like to dynamically assign values to a known class instance based on the Property name. An example describes perfectly what I want to do: There is a class

                public class AClass
                {
                public string _aValue;

                    public string AValue
                    {
                        get { return \_aValue; }
                        set { \_aValue = value; }
                    }
                }
                

                and I want to assing value to AClass.AValue without actually explicitly writing:

                AClass aInstance = new AClass();
                aInstance.AValue = "value";

                and now comes the best part. I'd like to avoid reflection as much as possible, because performance matters. I could go and look for a property named "AValue" and do

                typeof(AClass).GetProperty("AValue").SetValue(aInstance, "value", null);

                however that's veery slow. It's got to be possible to do that some other way, Linq works like this and it's not slow. any ideas?

                zilo

                C Offline
                C Offline
                Calin Tatar
                wrote on last edited by
                #8

                Basically, you are searching for an alternative to Reflection, right? Calin

                S 1 Reply Last reply
                0
                • C Calin Tatar

                  Basically, you are searching for an alternative to Reflection, right? Calin

                  S Offline
                  S Offline
                  Stevo Z
                  wrote on last edited by
                  #9

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

                  zilo

                  C 2 Replies Last reply
                  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
                    #10

                    I think you could try by using Dynamic Invocation. Calin

                    S 1 Reply Last reply
                    0
                    • 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

                        1 Reply Last reply
                        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

                          S 1 Reply Last reply
                          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

                            D Offline
                            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

                                      1 Reply Last reply
                                      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

                                        1 Reply Last reply
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