How to dynamically create generic C object using reflection

Question

In C  I have the following object   public class Item      public class Task lt T gt       public class TaskA lt T gt    Task lt T gt       public class TaskB lt T gt    Task lt T gt        I want to dynamically create TaskA or TaskB using C  reflection  Activator CreateInstance   However I wouldn t know the type before hand  so I need to dynamically create TaskA based on string like  namespace TaskA  or  namespace TaskAB

User · Answer

Make sure you re doing this for a good reason  a simple function like the following would allow static typing and allows your IDE to do things like  Find References  and Refactor -  Rename   public Task  lt T gt  factory  String name      Task  lt T gt  result     if  name CompareTo   A      0          result   new TaskA           else if  name CompareTo   B      0          result   new TaskB            return result

User · Answer

Indeed you would not be able to write the last line   But you probably don t want to create the object  just for the sake or creating it  You probably want to call some method on your newly created instance   You ll then need something like an interface    public interface ITask        void Process object o      public class Task lt T gt    ITask       void ITask Process object o              if o is T     Just to be sure  and maybe throw an exception         Process o as T            public void Process T o          and call it with    Type d1   Type GetType  TaskA      or  TaskB  Type   typeArgs     typeof Item     Type makeme   d1 MakeGenericType typeArgs   ITask task   Activator CreateInstance makeme  as ITask      This can be Item  or any type derived from Item task Process new Item       In any case  you won t be statically cast to a type you don t know beforehand   makeme  in this case   ITask allows you to get to your target type   If this is not what you want  you ll probably need to be a bit more specific in what you are trying to achieve with this

User · Answer

It seems to me the last line of your example code should simply be   Task lt Item gt  itsMe   o as Task lt Item gt     Or am I missing something

User · Answer

Check out this article and this simple example   Quick translation of same to your classes      var d1   typeof Task lt  gt    Type   typeArgs     typeof Item     var makeme   d1 MakeGenericType typeArgs   object o   Activator CreateInstance makeme     Per your edit   For that case  you can do this      var d1   Type GetType  GenericTest TaskA 1       GenericTest was my namespace  add yours Type   typeArgs     typeof Item     var makeme   d1 MakeGenericType typeArgs   object o   Activator CreateInstance makeme     To see where I came up with backtick1 for the name of the generic class  see this article   Note  if your generic class accepts multiple types  you must include the commas when you omit the type names  for example   Type type   typeof IReadOnlyDictionary lt   gt

User · Answer

I know this question is resolved but  for the benefit of anyone else reading it  if you have all of the types involved as strings  you could do this as a one liner   IYourInterface o    Activator CreateInstance Type GetType  Namespace TaskA 1 OtherNamespace TypeParam    as IYourInterface     Whenever I ve done this kind of thing  I ve had an interface which I wanted subsequent code to utilise  so I ve casted the created instance to an interface

[c#] How to dynamically create generic C# object using reflection?

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