How do you declare a Predicate Delegate inline?

c# delegates
Curtis picture Curtis · Sep 12, 2008 · Viewed 32.2k times · Source

So I have an object which has some fields, doesn't really matter what. I have a generic list of these objects.

List<MyObject> myObjects = new List<MyObject>();
myObjects.Add(myObject1);
myObjects.Add(myObject2);
myObjects.Add(myObject3);

So I want to remove objects from my list based on some criteria. For instance, myObject.X >= 10. I would like to use the RemoveAll(Predicate<T> match) method for to do this.

I know I can define a delegate which can be passed into RemoveAll, but I would like to know how to define this inline with an anonymous delegate, instead of creating a bunch of delegate functions which are only used in once place.

Answer

Erik van Brakel picture Erik van Brakel · Sep 12, 2008

There's two options, an explicit delegate or a delegate disguised as a lamba construct:

explicit delegate

myObjects.RemoveAll(delegate (MyObject m) { return m.X >= 10; });

lambda

myObjects.RemoveAll(m => m.X >= 10);

Performance wise both are equal. As a matter of fact, both language constructs generate the same IL when compiled. This is because C# 3.0 is basically an extension on C# 2.0, so it compiles to C# 2.0 constructs

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