how do you execute a function on a List of objects using LINQ

Question

I want to execute a function on all the objects within a List of objects using LINQ. I know i saw something similar on SO before but after several failed search attempts, i am posting this question

Answer 1

Try the following if it is actually of type List<T>.

C#

var list = GetSomeList();
list.ForEach( x => SomeMethod(x) );
' Alternatively
list.ForEach(SomeMethod);

VB.Net

Dim list = GetSomeList();
list.ForEach( Function(x) SomeMethod(x) );

Unfortunately .ForEach is only defined on List<T> so it cannot be used on any general IEnumerable<T> type. Although it's easy to code such a function

C#

public static void ForEach<T>(this IEnumerable<T> source, Action<T> del) {
  foreach ( var cur in source ) {
    del(cur);
  }
}

VB.Net

<Extension()> _
Public Shared Sub ForEach(Of T)(source As IEnumerable(Of T), ByVal del As Action(Of T)
  For Each cur in source
    del(cur)
  Next
End Sub

With this you can run .ForEach on any IEnumerable<T> which makes it usable from practically any LINQ query.

var query = from it in whatever where it.SomeProperty > 42;
query.ForEach(x => Log(x));

EDIT

Note to use the .ForEach for VB.Net. You must chose a function that returns a value. It's a limitation of lambda expressions in VB.Net 9 (VS 2009). But there is o work around. Say you want to call SomeMethod which is a Sub. Simply create a wrapper which returns an empty value

Sub SomeMethod(x As String) 
  ... 
End Sub

Function SomeMethodWrapper(x As String)
  SomeMethod(x)
  Return Nothing
End Function

list.ForEach(Function(x) SomeMethod(x)) ' Won't compile
list.ForEach(function(x) SomeMethodWrapper(x)) ' Works