Polymorhism

[Phenglai]

Got a question and I hope get an answer other than what I expect.

I am re-writing an application I wrote a few years ago and as always I am thinking, why in the world did I do it like this. I know we all have been there.

Anyway, the program controls remote cameras through the comm ports and I have created several dll's to help me accomplish this. Over the past few years, we have added new cameras and different ways of controlling them so the dll has grown with its class files. Currently there are 5 class files in the dll.

I would like to be able to have one global variable the use this as the means to interface with the dll. I currently cant get it work like I want it to and I dont want to have to declare 5 global variables just to be able to run everything.

Thanks in advance for your help,

Jerel

[shubha_de]

Hi Jeryl !

As far as i can understand your problem, you want to have one global object to interface with all the cameras. Now if it is not much of an effort, then you can add a CONTROLLER class to your scheme of designs. The CAMERA objects would be a (private) collection inside this class. You can have an ADDCAMERA Member to CONTROLLER Class, to add cameras when ever you require one. The CONTROLLER Class can then expose methods that take the CAMERA_ID and the action to be performed on it.

So if a member of the CONTROLLER class can be
ROTATE(CAMERA_ID)

and the collection of CAMERA objects are in a collection M_COLCAMERAS
Then you can within the CONTROLLER class's ROTATE method say something like

M_COLCAMERAS.ITEM(CAMERA_ID).ROTATE

Just thinking wild.

The CAMERA_ID would have to come from the UI that you give for controlling the APPLICATION.

[Phenglai]

I think I see where you are going but the dll file contains 5 classes that are all unique with there own control sets.

So I have say

ControlSet1
ControlSet2
etc.

I want to be able to do this

in a module

Public gControl as Object

then in the program when I control ControlSet1

Set gControl = new ControlSet1
gControl.MoveLeft

then in the program when I control ControlSet2

Set gControl = new ControlSet2
gControl.MoveLeft

That way the code reads the same and the only thing that is changing is the way the commands are sent to the camera.

Does that make sense?

[shubha_de]

Cant You use an interface and Make these CONTROLSETS implement that Interface. So then you can have an object of the interface and at runtime set it to the CONTROLSET you want to use.

Just some wild ideas....Happens when you have to think of something without knowing it fully...Found your topic interesting, that's why trying to think.

[Phenglai]

I figured it out.

I am using the globally declared object: gSysControl then instantiating it like so.

Set gSysControl = CreateObject("prjmsrcdll.IStandardCam")

I had to search the registry to find the library code name then late bind it so I can only use one variable to access all 5 control sets.

Glad I got one figured out.

Jerel

[yrwyddfa]

Maybe you could do it another way:

Say you declare an interface with all of the methods on which you want to control a camera (an abstraction, not a physical reality)

So, you might have

GetPicture()
TurnOn
TurnOff

You can then create an instantiation of that interface for each individual camera:

Implements MyCameraInterface
 
MyCameraInterface_GetPicture()
 
etc etc

This way you can treat all cameras equally, which means less client code, therefore less pain.

[Phenglai]

That is something I can look into. I am still in the baby stages of coding so its not to late to change.