What does "(item) =>" do?

Question

I'm trying to learn C# and MVC3. I wanted to have a WebGrid column as an Html.Action link, however, it wouldn't work until I did this:

grid.Column(format: (item) => Html.ActionLink("Edit", "Edit", new { id = item.Id }))

So I know that this fixes it but why? The (item) looks like a cast but what is the => for? From reading other questions I see that it's evidently bad to do this for some reason - why?

Thanks guys. The answer to [this](http://stackoverflow.com/questions/6167903/using-data-in-a-html-actionlink-inside-a-webgrid-column-not-possible) question is what had me worried. — BenGC, Aug 16 '11 at 18:13

score 8 · Accepted Answer · answered Aug 16 '11 at 18:06

8

This is known as a lambda expression / anonymous function in C#. The () portion is the argument list and the => indicates the right hand side is the body / expression of the lambda.

Here's a slightly expanded form which may be a bit clearer

Func<ItemType, string> linkFunction = (item) =>
{
  return Html.ActionLink("Edit", "Edit", new { id = item.Id });
};

answered Aug 16 '11 at 18:06

JaredPar

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I think you can drop the "/ anonymous function". Just lambda expression is more correct I think. – justin.m.chase Aug 16 '11 at 19:20
@justin.m.chase anonymous function is more encompassing because it covers both lambda expressions and anonymous methods – JaredPar Aug 16 '11 at 19:25

score 7 · Answer 2 · edited Aug 16 '11 at 20:09

7

That would be a lambda expression. And no, using lambda's is not bad, it's a (very) good thing.

edited Aug 16 '11 at 20:09

Andrew Hare

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answered Aug 16 '11 at 18:05

Claus Jørgensen

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@RichK: I upvoted the answer but removed "MSDN is your friend" because it added a condescending tone to an otherwise excellent answer. – Andrew Hare Aug 16 '11 at 20:07
Ah, it looks like I may have stomped out Claus's extra sentence there with my original edit. Sorry about that :) – Andrew Hare Aug 16 '11 at 20:09

What does "(item) =>" do?

2 Answers2