I'm new here and I created a simple class that emulates event subscribing. It's not as fancy as something in the .NET world, but it does provide a simple way to subscribe and unsubscribe multiple listeners to an "event".
It's simple to use. Just declare a variable for the event, add some subscribers to it, and call the appropriate raise method.
And obviously, if object1 or object2 had access to the event variable (say one declared in a module) they could subscribe to it themselves.
B4X:
'Class module
Sub Class_Globals
Private subscriptions As List
Private callbacks As List
End Sub
'Initializes the event. Must be called.
Public Sub Initialize()
subscriptions.Initialize
callbacks.Initialize
End Sub
'Stores the infromation to create a callback (by using CallSub)
'If the target and callback combination already exist, the existing callback will be replaced with the one provided.
'
'target: The object hosting the sub to call
'callback: The string of the sub to call when this event is raised
Public Sub Subscribe(target As Object, callback As String)
Dim index As Int = subscriptions.IndexOf(target)
Dim addItem As Boolean
addItem = index = -1
If (addItem = False) Then
If (callbacks.Get(index) <> callback) Then
subscriptions.RemoveAt(index)
callbacks.RemoveAt(index)
addItem = True
End If
End If
If (addItem) Then
subscriptions.add(target)
callbacks.add(callback)
End If
End Sub
'Removes the object from the subscription list.
'
'target: The object that should be unsubscribed from the event.
Public Sub Unsubscribe(target As Object)
Dim index As Int = subscriptions.IndexOf(target)
If (index <> -1) Then
subscriptions.RemoveAt(index)
callbacks.RemoveAt(index)
End If
End Sub
'Calls each subscriber of this event.
Public Sub Raise()
For Each deleg As Object In subscriptions
Dim callbackIndex As Int = subscriptions.IndexOf(deleg)
CallSub(deleg, callbacks.Get(callbackIndex))
Next
End Sub
'Calls each subscriber of this event, providing the supplied argument.
'
'arg1: The first argument to provide to each subscriber.
Public Sub Raise2(arg1 As Object)
For Each deleg As Object In subscriptions
Dim callbackIndex As Int = subscriptions.IndexOf(deleg)
CallSub2(deleg, callbacks.Get(callbackIndex), arg1)
Next
End Sub
'Calls each subscriber of this event, providing the supplied argument.
'
'arg1: The first argument to provide to each subscriber.
'arg2: The second argument to provide to each subscriber.
Public Sub Raise3(arg1 As Object, arg2 As Object)
For Each deleg As Object In subscriptions
Dim callbackIndex As Int = subscriptions.IndexOf(deleg)
CallSub3(deleg, callbacks.Get(callbackIndex), arg1, arg2)
Next
End SubIt's simple to use. Just declare a variable for the event, add some subscribers to it, and call the appropriate raise method.
B4X:
Dim myEvent As clsEvent
myEvent.Initialize()
myEvent.Subscribe(object1, "MyMethod")
myEvent.Subscribe(object2, "MyMethod")
myEvent.Raise()And obviously, if object1 or object2 had access to the event variable (say one declared in a module) they could subscribe to it themselves.
