method overloading and dynamic keyword in C#

Question

I still haven't upgraded to 4.0 else I would have checked the code snippet myself. But I hope some expert can comment on this.

In following code, will the appropriate Print() method be called at runtime? Is it even legal in C# 2010 to call it that way?

public void Test()
{
    dynamic objX = InstantiateAsStringOrDouble();

    Print(objX);
}

public void Print(string s)
{
    Console.Write("string");
}

public void Print(double n)
{
    Console.Write("double");
}

Thanks!

How would you want that to decide which Print to call? I think you'd be better off reading more about dynamic. — David Heffernan
– David Heffernan, Commented Apr 29, 2011 at 18:41
at runtime, of course. Thanks for your advice, I'm doing that already! :-) — Vishal Seth
– Vishal Seth, Commented Apr 29, 2011 at 18:57
It does work, but be careful with dynamic. It can solve a lot of issues and simultaneously give you a lot of headaches :-) basically you gain runtime flexibility but lose all compiler time checking. — James Michael Hare
– James Michael Hare, Commented Apr 29, 2011 at 19:00

James Michael Hare · Accepted Answer · 2011-04-29 18:59:15Z

3

Yes, that does in fact work. It will check the usage of the dynamic at runtime and call the appropriate method, however you lose almost all of your compile-time checking, so I'd make sure that's really what you'd want to do.

answered Apr 29, 2011 at 18:59

James Michael Hare

38.6k10 gold badges75 silver badges83 bronze badges

Sign up to request clarification or add additional context in comments.

1 Comment

Vishal Seth Over a year ago

Thanks James. The code I'm trying to convert has 3-4 levels deep method calls with passing boxed Object parameters. I thought of writing overloaded methods but its like some if-else logic, then a method call, more if-else logic than another method call (passing the same Object parameter it gets from 2-3 levels up)....Pain in the neck sort of legacy code. Somewhere down the bottom it checks if the Object is ArrayList or HashTable or blah blah and acts accordingly.

mellamokb · Accepted Answer · 2011-04-29 19:00:10Z

2

Yes, and you can even do this:

public dynamic InstantiateAsStringOrDouble() { return 0.5; }

or

public dynamic InstantiateAsStringOrDouble() { return "hello"; }

and it will work as expected.

answered Apr 29, 2011 at 19:00

mellamokb

56.8k12 gold badges111 silver badges138 bronze badges

1 Comment

Lasse V. Karlsen Over a year ago

And of course, public dynamic ... { return true; } will probably not work.

Collectives™ on Stack Overflow

method overloading and dynamic keyword in C#

2 Answers 2

1 Comment

1 Comment

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

1 Comment

1 Comment

Your Answer

Sign up or log in

Post as a guest

Linked

Related