I have a form with a button and the following code:
vb.net Code:
  1. Public Class Form1

  2.     Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click

  3.         Dim dt As New DataTable

  4.         dt.Columns.Add("CustomerId", GetType(Integer))

  5.         dt.Columns.Add("Rate", GetType(Integer))

  6.         For i = 0 To 9

  7.             dt.Rows.Add(i, 0)

  8.         Next

  9.  
  10.         Dim dataRows = dt.Rows.Cast(Of DataRow)().ToList

  11.         dataRows.ForEach(AddressOf SetRate)                 '<-- this works

  12.         ' dataRows.ForEach(Function(dr) dr("Rate") = 9999)    '<-- this doesn't work!

  13.         For Each dr In dt.Rows

  14.             Console.WriteLine(dr("CustomerId") & "     " & dr("Rate"))

  15.         Next

  16.     End Sub

  17.  
  18.     Sub SetRate(ByVal dr As DataRow)

  19.         dr("Rate") = 9999

  20.     End Sub

  21. End Class

Output in when I do: dataRows.ForEach(AddressOf SetRate)
Code:
0     9999
1     9999
2     9999
3     9999
4     9999
5     9999
6     9999
7     9999
8     9999
9     9999
Output when I do: dataRows.ForEach(Function(dr) dr("Rate") = 9999)
Code:
0     0
1     0
2     0
3     0
4     0
5     0
6     0
7     0
8     0
9     0
I was assuming both the codes are equivalents, but they don't seem to be so. Though there are no compilation errors, the inline-function way doesn't work.
Anyone knows the reason why? Is it because the lambda expressions are evaluated when they are first used? Or is there any other reason?