Lambda Expression using Foreach Clause [duplicate]

Question

Possible Duplicate:
Why is there not a ForEach extension method on the IEnumerable interface?

EDIT

For reference, here's the blog post which eric referred to in the comments

https://ericlippert.com/2009/05/18/foreach-vs-foreach/

ORIG

More of a curiosity I suppose but one for the C# Specification Savants...

Why is it that the ForEach() clause doesn't work (or isn't available) for use on IQueryable/IEnumerable result sets...

You have to first convert your results ToList() or ToArray() Presumably theres a technical limitation to the way C# iterates IEnumerables Vs. Lists... Is it something to do with the Deferred Execution's of IEnumerables/IQuerable Collections. e.g.

var userAgentStrings = uasdc.UserAgentStrings .Where<UserAgentString>(p => p.DeviceID == 0 && !p.UserAgentString1.Contains("msie")); //WORKS userAgentStrings.ToList().ForEach(uas => ProcessUserAgentString(uas)); //WORKS Array.ForEach(userAgentStrings.ToArray(), uas => ProcessUserAgentString(uas)); //Doesn't WORK userAgentStrings.ForEach(uas => ProcessUserAgentString(uas));

I'd write ForEach(uac => ProcessUserAgentString(uas)) as ForEach(ProcessUserAgentString). — Mehrdad Afshari
– Mehrdad Afshari, Commented May 13, 2009 at 16:54
What's the problem with a conventional for-each loop? foreach (var uas in UserAgentStrings) ProcessUserAgentString(uas); — Dario
– Dario, Commented May 13, 2009 at 16:54
Theres no problem... Like I said, it was more of a curiousity why the convention was available to use on Arrays/Lists but not on IQueryables/IEnumerables and as Eric Lippert pointed out below, it's a completely philosophical choice by the dev team and not for any technical reasons — Eoin Campbell
– Eoin Campbell, Commented May 13, 2009 at 17:02
Here's an alternative idea of how this could be possible: visualstudio.uservoice.com/forums/121579-visual-studio-2015/… — HappyNomad
– HappyNomad, Commented Oct 6, 2016 at 6:32

LukeH · Accepted Answer · 2010-10-06 14:27:07Z

It's perfectly possible to write a ForEach extension method for IEnumerable<T>.

I'm not really sure why it isn't included as a built-in extension method:

Maybe because ForEach already existed on List<T> and Array prior to LINQ.
Maybe because it's easy enough to use a foreach loop to iterate the sequence.
Maybe because it wasn't felt to be functional/LINQy enough.
Maybe because it isn't chainable. (It's easy enough to make a chainable version that yields each item after performing an action, but that behaviour isn't particularly intuitive.)

public static void ForEach<T>(this IEnumerable<T> source, Action<T> action) { if (source == null) throw new ArgumentNullException("source"); if (action == null) throw new ArgumentNullException("action"); foreach (T item in source) { action(item); } }

point taken, but the question was more in reference to why it's not available out of the box... i.e. Array has a static ForEach() method. List has one... Why don't IEnumerable/IQueryable
I guess we'll have to wait for Eric's blog post to find out the real answer ;)

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