BYOB question
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anne mulhern
Member
March 07, 2012
HI!
This is the best venue I can think of for my question although I know it's not quite the right one.
Does anybody know how I can check if a BYOB sprite has a parent? I'm looking to delete all clones except the prototype. There is an
attribute parent
block
but I don't know how to check if this block is null or not.
Thanks!
The answer was a big help. But I think it raises a problem that has arisen in programming languages over and over again.
When I evaluate <attribute parent> I get <nil>. Now, it turns out that <nil> is equal to <false> which is why the suggestion works. But, even though <nil> is equal to <false> if I try to use it in the same way as <false> I run into difficulties.
This creates a sort of semantic difficulty because the two values are clearly not equal.
Would a separate <isnil?> operator be better?
> Would a separate <isnil?> operator be better?
Yes, I guess it would. A "nil" could be added to the list of the "is a" operator.
Thanks!
Works a charm.
- mulhern
Compare the <attribute parent> block to <false> (from Operators). If the comparison in True than the sprite has no parent.