Question

I’m trying to make a part of my code more fluent.

I have a string extension that makes an HTTP request out of the string and returns the response as a string. So I can do something like…

string _html = "http://www.stackoverflow.com".Request();

I’m trying to write an extension that will keep trying the request until it succeeds. My signature looks something like…

public static T KeepTrying<T>(this Func<T> KeepTryingThis) {
  // Code to ignore exceptions and keep trying goes here
  // Returns the result of KeepTryingThis if it succeeds
}

I intend to call it something like…

string _html = "http://www.stackoverflow.com".Request.KeepTrying();

Alas, that doesn’t seem to work =). I tried making it into a lambda first but that doesn’t seem to work either.

string _html = (() => "http://www.stackoverflow.com".Request()).KeepTrying();

Is there a way to do what I’m trying to do while keeping the syntax fairly fluent?
Suggestions much appreciated.

Thanks.

Answer 1

You can’t use a method group for extension methods, or lambda expressions. I blogged about this a while ago.

I suspect you could cast to Func<string>:

string _html = ((Func<string>)"http://www.stackoverflow.com".Request)
                    .KeepTrying();

but that’s pretty nasty.

One alternative would be to change Request() to return a Func, and use:

string _html = "http://www.stackoverflow.com".Request().KeepTrying();

Or if you wanted to keep the Request method itself simple, just add a RequestFunc method:

public static Func<string> RequestFunc(this string url)
{
    return () => url.Request();
}

and then call:

string _html = "http://www.stackoverflow.com".RequestFunc().KeepTrying();