Meaning of () => Operator in C#, if it exists

I read this interesting line here, in an answer by Jon Skeet.

The interesting line is this, where he advocated using a delegate:

Log.Info("I did something: {0}", () => action.GenerateDescription());

Question is, what is this ()=> operator, I wonder? I tried Googling it but since it's made of symbols Google couldn't be of much help, really. Did I embarr开发者_如何学运维assingly miss something here?

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This introduces a lambda function (anonymous delegate) with no parameters, it's equivalent to and basically short-hand for:

delegate void () { return action.GenerateDescription(); }

You can also add parameters, so:

(a, b) => a + b

This is roughly equivalent to:

delegate int (int a, int b) { return a + b; }

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=> this is lambda operator. When we don't have any input parameters we just use round brackets () before lambda operator.

syntax: (input parameters) => expression

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This is an example of a lambda expression you can learn more here.

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It's way to pass anonymous delegate without parameters as lambda expression.

Similar to this from .NET 2.0

Log.Info("I did something: {0}", delegate()
            {
                return action.GenerateDescription();
            });

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Creating an anonymous delegate to specified method.

Probably, in your case it will be a Func<string>