C# Quiz: Will that compile?

re: C# Quiz: Will that compile?

Eric Maino — Tue, 21 Dec 2004 23:44:00 GMT

This should not compile becuase the compiler can't tell of which type the anonymous delegate is.

If the function only took one type of delegate the code should compile beucase you wouldn't have any ambiguity.

re: C# Quiz: Will that compile?

tum — Tue, 21 Dec 2004 23:46:00 GMT

I can't really see why it wouldn't unless the spec changed since I last looked. You aren't required to provide anonymous method parameter lists anymore are you?

I assume the line wrapping within a string literal is an html thing not your actual code :)

re: C# Quiz: Will that compile?

tum — Tue, 21 Dec 2004 23:49:00 GMT

What are the prototypes of the other Thread constructors? I only have the 1.1 docs here and Thread only has one constructor.

re: C# Quiz: Will that compile?

Matt Berther — Wed, 22 Dec 2004 00:06:00 GMT

Im guessing you need to do something like this:

new Thread(new ThreadStart(delegate { Console.WriteLIne("On another thread"); })).Start();

re: C# Quiz: Will that compile?

tum — Wed, 22 Dec 2004 00:29:00 GMT

new Thread(new ThreadStart(delegate { Console.WriteLIne("On another thread"); })).Start();

I don't think that's it. threadstart *is* a delegate.

Assuming Thread.ctor takes two different types of delegates, the solution would be to provide an explicit parameter list for the anonymous delegate

i.e

new Thread(delegate() { Console.WriteLine("On another thread"); }).Start();

Assuming Thread and ThreadStart look like they do in ver 1.1.

Freudian slip

some guy — Wed, 22 Dec 2004 00:52:00 GMT

they say a freudian slip is when you say one thing but mean your mother. or in this case, "the old grey mater" which is not a very kind way of referring to her. :-)

re: C# Quiz: Will that compile?

James Manning — Wed, 22 Dec 2004 03:35:00 GMT

First Close/Dispose and now this! :)

re: C# Quiz: Will that compile?

Brad Abrams[MSFT] — Wed, 22 Dec 2004 04:00:00 GMT

Some guy -- thanks, fixed ;-) I hope my mother doesn't see this ;-)

re: C# Quiz: Will that compile?

Judah — Wed, 22 Dec 2004 04:54:00 GMT

new Thread(delegate
{
Console.WriteLine("On another thread");
}).Start();

Would work if 1.1 supported anonymous methods. :-) But in 2.0, Thread.Start has overloads allowing a parameterized thread start, which means the compiler can't figure out which one to use, ThreadStart or ParameterizedThreadStart. So no, it won't compile.

This should compile:

// tell the compiler it should be a ThreadStart
new Thread((ThreadStart)delegate
{
Console.WriteLine("On another thread");
});

re: C# Quiz: Will that compile?

Joe Duffy — Wed, 22 Dec 2004 05:31:00 GMT

Judah brings up an interesting point...

Who would've thunk that introducing a new ctor overload would end up breaking people? Interestingly, though, if we had anonymous delegate support in v1.1 and folks coded up something like what you've shown, introducing the new Thread.ctor(ParameterizedThreadStart) overload would prevent that same source from compiling without modification on v2.0.

Luckily this isn't the case. :)

Hmm!

re: C# Quiz: Will that compile?

tum — Wed, 22 Dec 2004 06:17:00 GMT

Judah,

I suspected they may have added a thread start with state attached (tho that wouldn't be needed if you used an anonymous method worth closures ;)).

Does this compile?

new Thread(delegate() { Console.WriteLine("On another thread"); }).Start();

The empty parameter list should be enough for the compiler to work out which delegate type you want constructed. ...

re: C# Quiz: Will that compile?

Judah — Thu, 23 Dec 2004 00:12:00 GMT

Yes, with the parameterless delegate, the compiler can figure out that you're using the parameterless ThreadStart delegate.

C# Quiz: Will that compile? [Answer]

Brad Abrams — Mon, 27 Dec 2004 22:55:00 GMT

C# Quiz: Will that compile?

Managed from down under — Tue, 28 Dec 2004 14:31:00 GMT

re: C# Quiz: Will that compile?

Shon Dot Net Dude — Tue, 04 Jan 2005 07:21:00 GMT

It will not compile <Span>

ParameterisedThreadStart

Community Blogs — Sun, 16 Jul 2006 18:14:38 GMT

Just to prove that I am a true geek I thought I would tackle Brad Abrams latest C# quiz. The simple answer