On 16 Oct 2014, at 16:43, Adriaan van Os wrote:
Jonas Maebe wrote:
No, it won't:
1) if the external code expects it to be "out" and you declare it
as "var": the caller will decrease the reference count and the
ppEvent that you get will have as initial value "nil". You can just
assign to it like normal.
2) if the external code expects it to be "var" and you declare it
as "out": the caller will not do anything and hence the ppEvent
will not be nil. However, assignments to the "out" parameter still
cause its reference count to be decreased. After all, you can
assign multiple times to an "out" parameter, so the compiler cannot
assume it's already nil. The only problem that could happen here is
if you would explicitly write your code in a way that behaves
differently depending on whether the initial value is nil (e.g.,
assigning something to it only in one branch of an if-statement,
and then later checking whether it's "still" nil to determine
whether you have to assign something else to it).
Sorry, but the above explanation flabberghasts me.
I explained the opposite scenario as you: calling a method implemented
in Pascal from external Windows code (with mismatched var/out
modifiers). Rereading your message, that's indeed not what you were
talking about.
In general, using wrong/mismatched modifiers when importing routines
virtually always causes problems though (and often much worse than
just a memory leak), there's nothing special about reference counted
types here.
Jonas
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