Sean,
I understand your point, but I would still expect IsDefined("thing.foo") to
return true when thing.foo = null. It _is_ technically defined, it just
happens to have a value of null, or rather, it is not set to an instance
variable or simple type. I think IsNull (which CF lacks) and IsDefined are
very different indeed.
Think of other languages (Java seems appropriate) that _do_ have a concept
of null. You can compare (thing.foo == null) for a Boolean result without
generating an exception because foo does indeed exist! Not having a value
and not being defined are two very different states. I've always found the
behavior of IsDefined to be a bit off.
Roland Collins
-----Original Message-----
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf
Of Sean A Corfield
Sent: Wednesday, February 25, 2004 10:20 PM
To: [EMAIL PROTECTED]
Subject: Re: [CFCDev] Testing For [undefined struct element]
On Feb 25, 2004, at 1:23 PM, David Ross wrote:
> Yes, this is exactly what's happening. CF has a concept of NULL
> (otherwise how would cfdump spit out "undefined struct element"), it
> just likes to throw errors before allowing you to test for it.
>
> Basically, I have arrived at if structkeyExists() == true and assigning
> the value into a dummy var errors, then it's null. Talk about
> overhead...
Hmm, that doesn't really make sense to me. If thing.foo is null then
isDefined("thing.foo") should be *false* even tho'
structKeyExists(thing,"foo") is true. Can you show a reproducible
example of what you're seeing?
Regards,
Sean
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