Re: __gc visible to lua code...
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- Subject: Re: __gc visible to lua code...
- From: Graham Wakefield <lists@...>
- Date: 2007年3月30日 10:58:29 -0700
On Mar 30, 2007, at 9:35 AM, Michael Broughton wrote:
One way you can prevent the __gc metamethod from being called is to
create an __index metamethod that filters out private indices. Of
course, that would not prevent any C code from calling your
finalizer. Overall, I think this solution is too complicated and it
will slow down your whole module.
I agree.
I think it is best to just keep track of the state of your userdata
and any associated resources. For example: if your userdata is a
struct, add a field to mark when it is finalized. If your userdata
is a boxed pointer, make sure you nullify the pointer when you are
done with it.
Yes, I've done this now... but still I think __gc should be private
by default.
You could also use each userdata's environment table to do
something similar.
? You mean, in __gc set the userdata environment to nil, and then in
the type-check test if the environment is nil, for example? Or
likewise for a field in the environment? Probably null-checking the
userdata value is easier.
Another question: is the userdata's environment garbage collected
when __gc is called, or when the userdata itself is garbage collected?