How to implement a Stack 5

[camjon]

I want to know if anyone knows how to implement a stack in vba

 

[Craig0201]

Gents,

I'm glad you've found the techniques useful. They're not exactly common or garden but they can really help in structuring your code for flexibility for the future. I can foresee a whole load of Access programs with lots of Undo functionality coming up soon!

If anyone would like to see a simple example of using Command pattern to get Undo functionality in VBA, let me know.

C

 

[oharab]

Craig,
I'd love to see it. I can't think of any useful scenarios yet, but I'm sure I will in the future!

Ben.

----------------------------------------------
Ben O'Hara

http://www.RobotParade.co.uk

We could be confused in exactly the same way, but confusion might be like Nulls, and not comparable.

 

[Craig0201]

Ben,

A contrived example is uploaded here.

http://www.megaupload.com/?d=O6CCDX2Q

Very simple, very contrived but shows the principles.

Craig

 

[oharab]

Contrived samples rule! TBH, most of my work is contrived, so should help loads!!

Cheers
B.


----------------------------------------------
Ben O'Hara

http://www.RobotParade.co.uk

We could be confused in exactly the same way, but confusion might be like Nulls, and not comparable.

 

[Craig0201]

As soon as you save it, you notice an error!

Please substitute the code for LightOn and LightOff with

Private Sub LightOnButton_Click()

    Dim comm As Command
    Dim ctrl As Control
    
    Set comm = New LightOnCommand
    Set ctrl = Light
    
    comm.DoAction Null, ctrl
    undoStack.Push comm
    
    Command3.Enabled = True

End Sub

Private Sub LightOffButton_Click()

    Dim comm As Command
    Dim ctrl As Control
    
    Set comm = New LightOffCommand
    Set ctrl = Light
    
    comm.DoAction Null, ctrl
    undoStack.Push comm
    
    Command3.Enabled = true

End Sub

I forgot to enable the undo button.

Also.....in my rush to get this up, both

C

 

[Craig0201]

Blimey...I do get ahead of myself!

I meant to type

Each of the Command3.Enabled lines from the textboxes and Light command buttons can read Command3.Enabled = True. By definition, I know I have just pushed an item to the stack and therefore know the result of the IsEmpty test.

C