Pass Delegate Into Method

General
1

Is it possible to pass a delegate into a method like this?

Sub GetInfoForMethod(sender as TheSender) As String
#pragma unused TheSender

Return "My string expression"
End Sub

Sub MyCodeToUsePassedDelegate
SomeModule.DoStuffUsingPassedDelegate(AddressOf GetInfoForMethod)
End Sub

Dub DoStuffUsingPassedDelegate
msgbox GetInfoForMethod.Invoke
End Sub

The code doesn’t give a good example of how I would use this in a real-world app but it at least shows what I’m trying to achieve. I understand that this can be done using classes but is there I way I can avoid classes to achieve this?

Thanks

3

I’m using Introspection to achieve this. Any suggestions are still welcome. Thanks

4

Dead happy! :slight_smile: My graphics layering system works!!

5

You can pass anything that’s an object or type as a parameter.

Delegates are really cool once you get your head around them. Don’t forget you can call Delegate.Invoke…

6

[quote=208197:@Jon Ogden]You can pass anything that’s an object or type as a parameter.

Delegates are really cool once you get your head around them. Don’t forget you can call Delegate.Invoke…[/quote]
What kind of syntax do you use to pass a delegate into a method? Introspection is really cool and for the design of my code probably better than using a delegate but I still want to understand how to use it.

7

Well, you first create your delegate. Then in your properties of the object where the delegate resides, you create a property of the type of your created delegate. Now you can pass that property as a parameter of the method. I use it in code to create flexible event handlers for certain controls. Works really well.

9

Thanks

10 
Private Delegate Function delDataAvailable(sender as IPSwitchCommands) As Boolean

So that’s my delegate signature.

Now here is my property:

Private DataAvailableCallback As delDataAvailable

Here it is passed as a parameter:

Sub SetDataAvailableHandler(theCallback as delDataAvailable)
  DataAvailableCallback = theCallback
End Sub

Adding the initial handler…

AddHandler me.DataAvailable, AddressOf HandleDataAvailable

Here’s the handler function…

Private Function HandleDataAvailable(sender as IPSwitchCommands) As Boolean
  If DataAvailableCallback <> nil Then
    Return DataAvailableCallback.Invoke(self)
  End If
End Function

Now we set up the delegate by calling the SetDataAvailableHandler method:

IPSwitch.SetDataAvailableHandler(AddressOf IPSwitch_DataAvailable)

IPSwitch_DataAvailable is a method. This handles the DataAvailable events from a serial socket.

11

[quote=208213:@Jon Ogden] Private Delegate Function delDataAvailable(sender as IPSwitchCommands) As Boolean

So that’s my delegate signature.

Now here is my property:

Private DataAvailableCallback As delDataAvailable

Here it is passed as a parameter:

Sub SetDataAvailableHandler(theCallback as delDataAvailable)
  DataAvailableCallback = theCallback
End Sub

Adding the initial handler…

AddHandler me.DataAvailable, AddressOf HandleDataAvailable

Here’s the handler function…

Private Function HandleDataAvailable(sender as IPSwitchCommands) As Boolean If DataAvailableCallback <> nil Then Return DataAvailableCallback.Invoke(self) End If End Function [/quote]
Thanks. I think if I follow these instructions when this kind of thing comes in handy I will get a good understanding of how to use it.

12

I’m not an expert on this at all and I had to look multiple times at my code to remember what I did. I got all this info from someone else here on the forum - I forget who. Search for Delegates or something like that to find more info. Really powerful feature of the language.

13

Thanks