What does "instance" mean?

[dav2010]

Hi,

I often see the word "Instance" in NI documentation, but, I don't have a clear understanding of what it means.  Can someone please offer a good definition of the word "Instance" as it pertains to Labview?  Here is an example of some documentation that would be more useful to me if I understood the intended meaning of the word "Instance"

"The instances of this polymorphic VI correspond to the I/O type of the channel, such as analog input, digital output, or counter output; the measurement or generation to perform, such as temperature measurement, voltage generation, or event counting; and in some cases, the sensor to use, such as a thermocouple or RTD for temperature measurements."

Does it just mean the occasion of usage? or application?

Thanks,

Dave

[crossrulz]

When dealing with polymorphics, the "instance" is the exact VI in the polymorphic that is being called.  As an example, I have a polymorphic VI "A".  The polymorphic has two instances, "Foo" and "Bar".  To bring in your example a little closer, when you wire up a string to the input of A, Foo is actually called.  If you wire up a double, Bar is called.  So when I wire up a string to A, the instance that is called is Foo.

Does this make any sense at all?

[dav2010]

No, sorry, not really.  What does "instance" mean?  In general, not just related to polymorphics....  It is widely used in the literature on NI.com for many different definitions.  Can you give a specific definition of the word "instance"?

Does "instance" mean VI in general?

[crossrulz · Accepted solution]

from the dictionary:a case or occurence of anything

I wouldn't necessarily say it generally means a VI.  More like an occurence of a VI.  It gets hard to explain the word without context here.  I say this because when you get into reentrant VIs, an instance is a particular clone of the VI that is in memory.