How Can I Pass Arguments to a Generic Constructor in C# Using the `new()` Constraint?

Using new() constraints in C# to pass parameters to generic constructors

When adding elements to a list, trying to create a new object of type T with constructor parameters, you may encounter a compilation error stating that the parameters cannot be provided when creating a variable instance. This error occurs even if there are constructor parameters in the class.

To solve this problem, new() constraints of generic types must be used. While this constraint allows the creation of parameterless instances, it is not sufficient for the case where constructor parameters are included.

The alternative is to introduce a parameter so that the object is created based on the parameter. Functions can accomplish this efficiently.

<code class="language-csharp">public static string GetAllItems<T>(..., Func<ListItem, T> del) {
  ...
  List<T> tabListItems = new List<T>();
  foreach (ListItem listItem in listCollection) 
  {
    tabListItems.Add(del(listItem));
  }
  ...
}</code>

This function can be called using a lambda expression that creates a new object with the required parameters:

<code class="language-csharp">GetAllItems<Foo>(..., l => new Foo(l));</code>

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