1. Create a normal class containing the public method(s) you need to be ‘static’
2. Include a public method [in this ‘static’ class] that initialises the [private] ‘static fields’ within the class (it can take parameters if you wish)
3. Create a module acts as a factory
Public Function CreateStaticClass(parameters for 'constructor') As StaticClass
Dim static As StaticClass
Set static = New StaticClass
Call StaticClass.Constructor(pass in parameters)
Set CreateStaticClass = static
End Function
4. you can now use the ‘static’ class by calling CreateStaticClass(‘parameters’).MethodName(‘parameters’)
there is no need to initialise the instance as that is done by the factory method
5. (Optional) If you want to enforce singleton instances you can create a module that acts as a singleton container – include a private instance variable and a public accessor property. optionally you can use a ‘let’ setter to allow the singleton to be ‘replaced’ with a new [static] class (using different constructor parameters – see #2,3). Use ‘Let’ for the setter, so you can assign the singleton without using ‘set’ ala OO languages
Private curStaticClass as StaticClass
Public Property Get CurrentStaticClass() As StaticClass
If curStaticClass Is Nothing Then Set curStaticClass = CreateStaticClass
Set CurrentStaticClass = curStaticClass
End Property
Public Property Let CurrentStaticClass(value As StaticClass)
If Not (curStaticClass Is Nothing) Then Set curStaticClass = Nothing
Set curStaticClass = value
End Property
6. To assign the singleton:
CurrentStaticClass = CreateStaticClass(parameters)
7. To use the singleton:
[value = ] CurrentStaticClass.MethodName(parameters)