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The Activator. CreateInstance method creates an instance of a type defined in an assembly by invoking the constructor that best matches the specified arguments. If no arguments are specified then the constructor that takes no parameters, that is, the default constructor, is invoked.
You declare an instance constructor to specify the code that is executed when you create a new instance of a type with the new expression. To initialize a static class or static variables in a non-static class, you can define a static constructor.
Yes.
(T)Activator.CreateInstance(typeof(T), param1, param2);
There is another way to pass arguments to CreateInstance through named parameters.
Based on that, you can pass a array towards CreateInstance. This will allow you to have 0 or multiple arguments.
public T CreateInstance<T>(params object[] paramArray)
{
return (T)Activator.CreateInstance(typeof(T), args:paramArray);
}
Keep in mind though that passing arguments on Activator.CreateInstance has a significant performance difference versus parameterless creation.
There are better alternatives for dynamically creating objects using pre compiled lambda. Of course always performance is subjective and it clearly depends on each case if it's worth it or not.
Details about the issue on this article.
Graph is taken from the article and represents time taken in ms per 1000 calls.
As an alternative to Activator.CreateInstance, FastObjectFactory in the linked url preforms better than Activator (as of .NET 4.0 and significantly better than .NET 3.5. No tests/stats done with .NET 4.5). See StackOverflow post for stats, info and code:
How to pass ctor args in Activator.CreateInstance or use IL?
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