xal posted on Wednesday, June 07, 2006
Following with the changes to validation rules I mentioned
here, here's an implementation of generic rules:
In order to do this I created:
Public Interface IRuleMethod
ReadOnly Property RuleName() As String
ReadOnly Property RuleArgs() As RuleArgs
Function Invoke(ByVal target As Object) As Boolean
End Interface
The rule handler was changed to this:
Public Delegate Function RuleHandler(Of T, C As RuleArgs)( _
ByVal target As T, ByVal e As C) As Boolean
There are many overloads of the AddRule() method with generic parameters besides the standard ones that we all use.
The benefits:
1) No code breaks. (This is because of the overloads in ValidationRules, ValidationRulesManager and SharedValidationRules.
2) You can write rules like:
Public Class SomeClass(Of T As SomeClass(Of T))
Inherits ActiveObjects.ActiveBusinessBase(Of T)
Private mSomeNumber as Integer = 0
Private Shared Function MyRule(ByVal target As SomeClass(Of T), _
ByVal e As Csla.Validation.RuleArgs) As Boolean
e.Description = "The number cannot be zero"
Return target.mSomeNumber <> 0
End Function
Public Property SomeNumber as Integer
...
End Property
Shared Sub New
Csla.Validation.SharedValidationRules.AddRule(Of SomeClass(Of T))( _
AddressOf MyRule, GetType(DateRangeChild(Of T)), "SomeNumber")
End Sub
End Class
Note that the target of the rule has the same definition as the class (this can be done with generic and non generic classes, of course) and the overloading also applies to instance or type rules.
I'm attaching the whole Validation Namespace classes so that it you can check it out. This includes the fix mentioned in the other thread.
Andrés
