Best way to determine whether a class will override method

[Ton Plomp]

I am trying to determine whether a class will override a specific method before running the override.

I am coming up with the following code:

Is this the preferred method?

An alternative (probably faster) would be:

 

 

Ton

[mje]

Is this in a scripting context?

 

The code you have makes a few assumptions, namely that the class is in the same folder as its VIs, and that all the classes aren't qualified by library names.

[Ton Plomp]

No it's not about scripting. 

I want to create a plugin class hierarchy and have a generic config GUI. If a class overrides a specific method I will enable a button that allows to open a class specific config GUI.

 

I don't think I make the assumption of the path relationship between the method and the class.

 

Ton

[mje]

Ah right, there's no path assumption. I still think a class qualified with a library name would cause issue though?

 

Maybe using a traditional dynamic dispatch method to query the class to see if it supports the option?

[Ton Plomp]

I can use the OpenG function 'Class name'  to find the qualified name of the class.

Since I will run this on the default value it will most likely not cost a lot of resources.

Questioning the class via a method is a maintenance nightmare for the class creator.

 

Ton

[Yair]

This could return a false positive if you run it on a class which doesn't inherit from your base class and has a VI with the same name, but I'm assuming you won't do that.

[Ton Plomp]

Thanks for the pitfall warning.

Ton

Thanks for the pitfall warning.

Ton

[shoneill]

Dunno, sounds like somethings a bit awry with your object hierarchy if you need to be manually checking for overrides.....

 

Havie you tried handing off the UI to the actual class?  That way they can automatically show the correct GUI.  Hint: Subpanels.

 

Shane.

[Yair]

And speaking on that specific topic, there were some discussions on this before. Here's one example - http://forums.ni.com/t5/LabVIEW/An-experiment-in-creating-compositable-user-interfaces-for/m-p/1262378#M529154

[MikaelH]

Just Create a method called "HasGUI" and let anybody override it and return True, if they want you to call it.

[drjdpowell]

I want to create a plugin class hierarchy and have a generic config GUI. If a class overrides a specific method I will enable a button that allows to open a class specific config GUI.

Would it be better to have a “ConfigGUI” object that was recursive (contained an optional subConfigGUI)?  Have a “Get ConfigGUI” method that has a “subConfigGUI” input.  The parent implementation would initialize the generic GUI and add the inputted subConfig GUI.  Child implementations could override the method to initialize a specific GUI and pass this in to the parent method.  The “display” (or whatever) method of the ConfigGUI object would enable the button if a non-default subConfigGUI was present.  That avoids any class introspection.  It would also work at any depth (so your more specific GUIs could themselves have even more specific sub-GUIs).

[Aristos Queue]

How about giving the class a method called "Get Editor GUI" that returns a VI refnum, and if it returns Not A Refnum then it has no special GUI and if it returns a refnum then you run that GUI? In other words, instead of overriding the editor VI directly, override the accessor VI for that GUI.