What exactly does Mapguide mean by Null

[Anonymous]

I am developing an appication via the API using client side VBScript. My app
invloves redlining and I must therefore test for existence of my redline
layer.

I am trying to test a variable which stores the layer object using the
IsNull(), IsObject() and IsEmpty() functions in VB. Whether an object exists
or not I always get the same results as follows:

IsNull():False
IsObject():True
IsEmpty(): False

I can verify the contents of the variable by writing it to the screen where
it returns [object] or [null] as I would expect, but none of the VB
functions identify null appropriately. Is there a new concept of a null
object that Microsoft are unaware of ??

Any ideas what is happening ?

Thanks,

Gary

[Anonymous]

Use this to check for existence of Your redline layer:

If map.getMapLayer("YourLayerName") is Nothing then
myLayer = map.createLayer("redline", "YourLayerName")
End If


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Krasnokutski Andrey
Russia, Yaroslavl
mailto:avk@kamisever.ru