I am wanting to construct an object from within a generic method. This object takes a string in its constructor. Something like this:
public T GetObject<T>()
{
return new T("Hello");
}
Is this possible?
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3 Answers
Yes, but only without compile-time checking if the constructor really exists: Activator.CreateInstance
public T GetObject<T>()
{
return (T)Activator.CreateInstance(typeof(T), "Hello");
}
3 Comments
Smashery
So if the
(string) constructor doesn't exist, it'll be a runtime error?
dtb
@Smashery: Exactly. It will throw an exception if
T doesn't have a public (string) constructor.Smashery
Thanks very much! Sucks I can only pick one "correct answer", but thanks for teaching me something new!
One option is to rewrite this to force the caller to pass in a factory method / lambda
public T GetObject<T>(Func<string,T> func)
{
return func("Hello");
}
The call site would be modified to look like this
GetObject(x => new T(x));
answered Nov 23, 2010 at 0:14
1 Comment
Smashery
The method signature gets a lot more complicated than dtb's solution, but I do like the compile-time checking that comes with it. Trade-offs, I guess.
No. At the moment you cannot use parameterised constructors with generic types since you cannot define them in where.
Using Activator is not the same - and I believe not the answer to your question - but you can use it of course.
answered Nov 23, 2010 at 0:04
