Re: [BUG] table will be garbage collected multiple times

[Andrew Gierth <andrew@...>]

>>>>> "Philippe" == Philippe Verdy <verdy_p@wanadoo.fr> writes:

 Philippe> It's not very well documented, but when a finalizer gets
 Philippe> called on an object, just before calling it, the GC first
 Philippe> clears the associated metatable if the object being finalized
 Philippe> is a table: in the finalizer for an object whose type is
 Philippe> 'table' or 'userdata', if you use getmetatable(self), it's
 Philippe> not documented clearly if either you'll get nil, or you'll
 Philippe> get the same metatable whose "__gc" entry is now nill,
 Philippe> something that should be better, allowing you to store the
 Philippe> "cnt" variable inside the metatable itself along with the
 Philippe> "__gc" variable, instead of the object being finalized).

I really don't know where you're getting this stuff, but it's all wrong.

The metatable of an object isn't changed in any way by garbage
collection, unless the __gc method chooses to do that itself (which is
sometimes a good idea, especially for userdatas where allowing method
calls on a post-finalization object(*) may be unwise). Inside the __gc
function for an object (whether table or userdata), getmetatable(self)
has the same value it had just before the object was collected, and
getmetatable(self).__gc is the __gc method being executed. Nor is the
metatable changed after the __gc method completes.

(*) - references to post-finalization objects can be easily obtained via
      the keys of ephemeron tables

-- 
Andrew.