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LabVIEW Idea Exchange

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David_L

Allow multiple event callback VIs

Status: Declined

Any idea that has received less than 8 kudos within 8 years after posting will be automatically declined.

As described here, LabVIEW will call certain event callback VIs when certain things happen such as LabVIEW startup or shutdown, creating a new VI, or calling Edit > Create SubVI.  The only problem is that there can only be one Callback VI per LabVIEW installation.  My suggestion is to allow more than one callback VI to be called when the events happen.  This can be useful if LabVIEW add-ons would like to implement the functionality without interfering with existing callback VIs.  

 

This is similar to my previous idea, but generalized for all the callback VIs.   

3 Comments
Mattias_Ericsson
Member

Excellent idea, this will definitly cause problems in the futures as more hooks/callback will be available for each new LabVIEW version. However, there could be more problems if all hook/callbacks are called in a sequence, I think I would prefer a configuration window, where user could select which of all hooks that should be used. E.g. if you have a hook for Create Sub VI and you add an addition "save VI" dialog with one toolkit and then you install another toolkit that do approx the same thing, then you don't want two dialog popup asking you to do the same. Usually it is only the functionallity from one of the toolkits you would like to use.

 

Mattias

AristosQueue (NI)
NI Employee (retired)

This idea specifically for Create SubVI was brought to me a few weeks ago from another party, and I said then that I don't think it is logically possible to support this.

 

Assume there are multiple callbacks. You cannot arbitrarily reorder the callbacks because each one leaves the new VI in a slightly different state. Any given plug-in will assume that the VI is in the original state and then modify it from there. If new items have been introduced by another plug-in, those probably aren't accounted for by the later plug-in. Thus any given installation of LabVIEW can only have one top-level plug-in. Now, that plug-in might itself define a second-level plug-in, but that's its business.

 

This is less true of start up and shutdown, but I can't kudos the idea in general because I don't see how Create SubVI could ever support it.

Darren
Proven Zealot
Status changed to: Declined

Any idea that has received less than 8 kudos within 8 years after posting will be automatically declined.