The longer I work with generics, the more I like them, and I continue to discover new ways to simplify my code by using them. More specifically, I like the ability to write type-safe code that is also more concise, efficient, and (above all) readable, because I don't have to use tons of CType and DirectCast operators. Today I gathered the generic methods I use more frequently in the following module. They are tiny and simple, yet they save me a lot of time and code.

Module GenericFunctions

   ' Swap two variables
   Public Sub Swap(Of T)(ByRef var1 As T, ByRef var2 As T)
      Dim tmp As T = var1
      var1 = var2
      var2 = tmp
   End Sub

   ' Type-safe version of the IIF function
   ' returns valueOnTrue if expression is True, else returns valueOnFalse
   Public Function IIf(Of T)(ByVal expression As Boolean, ByVal valueOnTrue As T, ByVal valueOnFalse As T) As T
      If expression Then
         Return valueOnTrue
      Else
         Return valueOnFalse
      End If
   End Function

   ' Type-safe version of the Choose function
   ' returns the N-th element of a list of values, or the default value for T if index
   ' is less than 0 or higher than the number of values
   Public Function Choose(Of T)(ByVal index As Integer, ByVal values() As T) As T
      If index >= 0 AndAlso index < values.Length Then
         Return values(index)
      Else
         Return Nothing
      End If
   End Function

   ' Return the min value of a list
   Public Function Min(Of T As IComparable)(ByVal firstValue As T, ByVal ParamArray values() As T) As T
      Dim result As T = firstValue
      For Each value As T In values
         If result.CompareTo(value) > 0 Then result = value
      Next
      Return result
   End Function

   ' Return the max value of a list
   Public Function Max(Of T As IComparable)(ByVal firstValue As T, ByVal ParamArray values() As T) As T
      Dim result As T = firstValue
      For Each value As T In values
         If result.CompareTo(value) < 0 Then result = value
      Next
      Return result
   End Function

   ' Return True if a value is in specific range
   Public Function InRange(Of T As IComparable)(ByVal testValue As T, ByVal minValue As T, ByVal maxValue As T) As Boolean
      Return testValue.CompareTo(minValue) >= 0 AndAlso testValue.CompareTo(maxValue) <= 0
   End Function

   ' Retrieve a dictionary element of a given type, or the provided default value if the element isn't found
   ' (two overloads)
   Public Function GetDictionaryValue(Of TKey, TValue)(ByVal dict As Hashtable, ByVal key As TKey, ByVal defaultValue As TValue) As TValue
      If dict.ContainsKey(key) Then
         Return CType(dict(key), TValue)
      Else
         Return defaultValue
      End If
   End Function

   Public Function GetDictionaryValue(Of TKey, TValue)(ByVal dict As Dictionary(Of TKey, TValue), ByVal key As TKey, ByVal defaultValue As TValue) As TValue
      ' If the key is in the dictionary, the following statement stores the corresponding value
      ' in defaultValue, else it leave defaultValue unchanged
      dict.TryGetValue(key, defaultValue)
      Return defaultValue
   End Function

End Module