Have local variables outlived their usefulness??

[felan]

Hi,
Just wanted to find out if there are any uses of local variables that can't be achieved with property nodes of a control or indicator.
Or should NI scrap them... Any Ideas???





Labview 8 video tutorials available at www.fafiles.com

[Dennis_Knutson]

They should not be scrapped. See this thread. If you are using the value property node instead of a local variable, your program is taking a big performance hit. You had better update your tutorials.

Message Edited by Dennis Knutson on 02-22-2006 02:56 PM

[Darren]

As I'm sure has been pointed out countless times on these forums, the performance of a local variable is orders of magnitude better than using the Value property of a control or indicator.

-D

[smercurio_fc]

Not to mention that it also takes two steps to get to the Value property whereas with a local variable it's just one. Just had a nitpicking moment. Back to normal now.

[jasonhill]

In my (extremely humble) opinion, local variables are the GOTO of LabView.  Useful under specific conditions, but often misapplied by novice programers.  In addition, I do not think that NI should ever abandon any feature.  There are enough compatability issues between revisions without completely removing features.

[altenbach]

Local variables certainly have their use, but they are also easily abused.

Long ago, I wrote some thoughts:

http://forums.ni.com/ni/board/message?board.id=170&message.id=112401&query.id=0#M112401

Don't forget that we have now a third option in LabVIEW 8.0, the Shared Variable. It comes much closer to a viable local variable replacement and has a few very nice features. 🙂

[kehander]

Rather than start a new thread about this, perhaps my question is topical here:

Can you send different values from different frames of a Flat Sequence to a single indicator without using local variables, or do you have to use a Stacked Sequence instead?

[Darren]

How do you propose doing it any different way using a Stacked Sequence Structure?  If you want to write a value to an indicator, and you don't want to wire to its terminal, you must use a local variable or the Value property.

-D

[kehander]

Oh, that's right, sequence locals don't do that...

Well, I guess local variables are still useful that way. 🙂

[Dennis_Knutson]

And the best way is to not use either a flat or stacked sequence structure and wire directly to the indicator. If you replace the sequence structure with a state machine, you'll be much better off. Here's a simple one. LabVIEW ships with other examples.