Comments on: The Forgotten Delegate… http://lostintangent.com/2008/07/08/the-forgotten-delegate/ Code is never finished, only abandoned... Wed, 07 Jan 2009 01:41:52 +0000 http://wordpress.org/?v=2.3.1 By: Josh Reuben http://lostintangent.com/2008/07/08/the-forgotten-delegate/#comment-564 Josh Reuben Wed, 09 Jul 2008 06:20:11 +0000 http://lostintangent.com/2008/07/08/the-forgotten-delegate/#comment-564 too bad that void is not a first class citizen - otherwise you wouldnt need Action , you could just pass Funct too bad that void is not a first class citizen - otherwise you wouldnt need Action , you could just pass Funct

]]> By: Jonathan Carter http://lostintangent.com/2008/07/08/the-forgotten-delegate/#comment-556 Jonathan Carter Tue, 08 Jul 2008 18:24:39 +0000 http://lostintangent.com/2008/07/08/the-forgotten-delegate/#comment-556 @Alex That's a good point, and just to clarify I was referring only to code that I'm developing from scratch. If an API you're using requires a Func, then you have no choice. LINQ uses Funcs because they're very generic, which is exactly what you'd want in this case. A Func<T, TResult> is only equivalent to a Predicate<T> if TResult is a boolean, which leaves many other scenarios that merit the use of a Func<T, TResult>. With that said, I'm not really sure why some of the standard query operators in LINQ use Func<T, bool> instead of Predicate (i.e SkipWhile, TakeWhile, Where). I'd imagine it's for consistency sake, since Funcs are leveraged throughout. -Jonathan @Alex

That’s a good point, and just to clarify I was referring only to code that I’m developing from scratch. If an API you’re using requires a Func, then you have no choice.

LINQ uses Funcs because they’re very generic, which is exactly what you’d want in this case. A Func is only equivalent to a Predicate if TResult is a boolean, which leaves many other scenarios that merit the use of a Func.

With that said, I’m not really sure why some of the standard query operators in LINQ use Func instead of Predicate (i.e SkipWhile, TakeWhile, Where). I’d imagine it’s for consistency sake, since Funcs are leveraged throughout.

-Jonathan

]]> By: Alex Simkin http://lostintangent.com/2008/07/08/the-forgotten-delegate/#comment-553 Alex Simkin Tue, 08 Jul 2008 13:48:15 +0000 http://lostintangent.com/2008/07/08/the-forgotten-delegate/#comment-553 The reason why I do not use Predicate is that Linq doesn't use it, so the following won't compile: Predicate IsPreferred; Customer c = customers.Where(IsPreferred).SingleOrDefault(); "Where" expects Func and there is no way to convert one delegate to the other. The reason why I do not use Predicate is that Linq doesn’t use it, so the following won’t compile:

Predicate IsPreferred;
Customer c = customers.Where(IsPreferred).SingleOrDefault();

“Where” expects Func and there is no way to convert one delegate to the other.

]]> By: ASP.NET MVC Archived Blog Posts, Page 1 http://lostintangent.com/2008/07/08/the-forgotten-delegate/#comment-552 ASP.NET MVC Archived Blog Posts, Page 1 Tue, 08 Jul 2008 12:47:49 +0000 http://lostintangent.com/2008/07/08/the-forgotten-delegate/#comment-552 [...] The Forgotten Delegate… (7/8/2008)Tuesday, July 08, 2008 from lostintangent.comLast week I was doing some pair programming with Jason Olson and we were looking over a project I’m working on in connection with ASP.NET MVC and [...] […] The Forgotten Delegate… (7/8/2008)Tuesday, July 08, 2008 from lostintangent.comLast week I was doing some pair programming with Jason Olson and we were looking over a project I’m working on in connection with ASP.NET MVC and […]

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