It seems to me that the "call parent method" doesn't work properly according to the description given in the LabVIEW help. I have two basic OOP functions I am doing examples for. I can get one to work easily and the other one is impossible. Background There are 3 basic situations in which you could use the "call parent method" You are calling the parent VI (or method) of a child VI from within the child VI You are calling the parent VI (or method) of a child VI from within a sibling VI You are calling the parent VI (or method) of a child VI from a different class/object. From the LabVIEW help system for "call parent method": Calls the nearest ancestor implementation of a class method. You can use the Call Parent Method node only on the block diagram of a member VI that belongs to a class that inherits member VIs from an ancestor class. The child member VI must be a dynamic dispatching member VI and have the same name as the ancestor member VI From my reading of that it means situation 3 is not supported but 1 & 2 should be. Unfortunately only Situation 1 works in LabVIEW 2012. Here is what I want And this is what I actually get What this means is that I can perform a classic "Extend Method" where a child VI will use the parent's implementation to augment it's functions BUT I cannot perform a "Revert Method" where I call the parent method's implementation rather than the one that belongs to the object. If you want a picture Any time I try and make operation2 the VI with the "call parent method" it shows up for about 1/2 sec and then turns into operation. So there are only 3 possibilities I can see Bug Neither situation 2 or 3 are intended to work (see above) and the help is misleading I just don't know what I am doing (and I am willing to accept this if someone can explain it to me) The downside is that if situation 2 above doesn't work it does make the "call parent node" much less usefull AND it's usage/application just doesn't make sense. You cannot just drop the "call parent node" on a diagram, it only works if you have an existing VI and you perform a replace. If you can only perform situation 1 (see above) then you should just drop the "call parent node" and it picks up the correct VI as there is only 1 option. Basically if situation 2 is not intended to work then the way you apply "call parent method" doesn't make sense. Attachements: For the really keen I have included 2 zip files One is the "Revert Method labVIEW project" which is of course not working properly because it wants to "call parent method" on operation not operation2 The other zip file is all pictures with a PIN for both "Revert Method" and "Extend Method" so you can see the subtle but important differences and pictrures of the relavant block diagrams including what NI suggested to me as the original fix for this problem but wasn't (they were suggesting I implement Extend Method). If you are wondering where I got the names, concepts and PIN diagrams from see: Elemental Design Patterns By: Jason McColm Smith Publisher: Addison-Wesley Professional Pub. Date: March 28, 2012 Print ISBN-10: 0-321-71192-0 Print ISBN-13: 978-0-321-71192-2 Web ISBN-10: 0-321-71255-2 Web ISBN-13: 978-0-321-71255-4 All the best David

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LabVIEW

LVOOP "call parent method" doesn't work when used in sibling VI

Author

tst/dkfire,

Thankyou for the tip about the "to more generic class". I have tried using this in a different example and was having some problems and this would explain it.

To answer both your questions about how I could misconstrue the help file. My problem is that I didn't make the connection between the node I was dropping into the VI and the VI it was applying to. Some of this was as a result of the initial dropping of the node not working (because the parent VI's were not built and it didn't work obviously).

At the end of the day I was using the node in the block diagram of the operation VI which also had a parent DD VI so I read that as the first part of the requirements met.

I was wanting it to use the operation2 child VI which was a DD VI and had the same name as the operation2 ancestor VI I wanted to call which to me satisfied the requirements as well.

tst, you asked the retorical question "Which VI?" well to me that answer was not obvious. I figured I had satisfied all the requirements and it should therefore work.

Can I see where I went wrong? Yes.

Do I think the help needs to be changed? Sorry guys but yes I do.

All the best

David