Passing arguments to C# generic new() of templated type

by

In order to create an instance of a generic type in a function you must constrain it with the “new” flag. 

public static string GetAllItems<T>(...) where T : new()

However that will only work when you want to call the constructor which has no parameters. Not the case here. Instead you’ll have to provide another parameter which allows for the creation of object based on parameters. The easiest is a function. 

public static string GetAllItems<T>(..., Func<ListItem,T> del) {
  ...
  List<T> tabListItems = new List<T>();
  foreach (ListItem listItem in listCollection) 
  {
    tabListItems.Add(del(listItem));
  }
  ...
}

You can then call it like so

GetAllItems<Foo>(..., l => new Foo(l));

More Related Contents:

  1. In C#, why can’t a List object be stored in a List variable
  2. No generic implementation of OrderedDictionary?
  3. Making a generic property
  4. foreach vs someList.ForEach(){}
  5. Why cannot C# generics derive from one of the generic type parameters like they can in C++ templates? [duplicate]
  6. No type inference with generic extension method
  7. Passing a single item as IEnumerable
  8. How do I make the return type of a method generic?
  9. Static Generic Class as Dictionary
  10. Get a generic method without using GetMethods
  11. explicitly cast generic type parameters to any interface
  12. Anonymous Types – Are there any distingushing characteristics?
  13. A reusable pattern to convert event into task
  14. Collection of generic types
  15. C# Generic Type Inference With Multiple Types
  16. How do I create a generic class from a string in C#? [duplicate]
  17. Parse string to enum type
  18. Declare a generic type instance dynamically [duplicate]
  19. T must be contravariantly valid
  20. What does new() mean?
  21. Ambiguous call between two C# extension generic methods one where T:class and other where T:struct
  22. How do I tell if a type is a “simple” type? i.e. holds a single value
  23. How to define generic type limit to primitive types?
  24. Why doesn’t C# support implied generic types on class constructors?
  25. What’s Wrong with an ArrayList?
  26. Implementing arithmetic in generics?
  27. Are static members of a generic class tied to the specific instance?
  28. Convert DataTable to List
  29. How to make correct clone of the List? [duplicate]
  30. Why it is not possible to define generic indexers in .NET?

Leave a Comment