Proposed Refactoring: Introduce Parameter in Lambda

Given a lambda with a captured local variable,

1. Add a new parameter to the lambda
2. Inside the lambda, replace uses of the local with uses of the new parameter
3. Where the lambda is called, pass in the local.
   

	// Given:
	Y y = ...
	Action action = () => {
	var x = F(y);
	G(x);
	};
	action();
	// After:
	Y y = ...
	Action action = (_y) => {
	var x = F(_y);
	G(x);
	};
	action(y);

view raw Promote captured local to parameter.cs hosted with ❤ by GitHub

I believe this is a refactoring: I believe that this transformation has no effect on the behavior of the code. But I'm not completely certain.

This operation is not allowed if the value of the local is changed inside the lambda.

This is almost the same operation as Introduce Parameter.

Proposed refactoring: extract and execute lambda

Given a statement block, wrap it in a lambda assigned to an Action variable, and execute it immediately.

	// Given:
	var y = ...;
	{
	var x = F(y);
	G(x);
	}
	// After
	Action action = () => {
	var x = F(y);
	G(x);
	};
	action();

view raw Extract and execute lambda.cs hosted with ❤ by GitHub

I believe this is a refactoring: I believe that this transformation has no effect on the behavior of the code. But I'm not completely certain.

I think a similar recipe for expressions is equally valid, using a Func<> instead of Action.

This is almost the same operation as Extract Method.