Re: Unexpected order of __finalize

I forgot that I modified luabind to not require an __init method. I'm not
sure why you are getting different results with the __init added though,
I'll have to try with an unmodified version of luabind.

Max

--
Technical Director
Unknown Worlds Entertainment
http://www.unknownworlds.com


On Tue, Aug 31, 2010 at 8:58 PM, Nigel Atkinson <[email protected]>wrote:

> Well that's strange!  Oh wait.. ah ha! I tried your program in an
> interactive Lua console, with luabind and found something not very
> obvious if you were running this as a complete chunk.
>
> The program is actually failing to completely create a 'B', as there is
> no __init() function for it.  So the 'B' finalise gets called, and
> because there was an error in the A init, A gets zapped and finalised as
> well.  In that order.  The program only makes it to "local a = A()"
>
> It seems to work as expected if you add an init function for B.
>
> Nigel
>
> On Tue, 2010-08-31 at 18:54 -0700, Max McGuire wrote:
> > For what it's worth, I was able to make things work the way I expected
> > to by storing the environment table for an object instance in the
> > global registry (I set it in set_instance_value).  This prevents the
> > table from being garbage collected. I remove it from the global
> > registry after the __finalize method has been called on the object in
> > destroy_instance.
> >
> > I'd be interested to hear what the developers have to say about this
> > "issue" and fix.
> >
> > Max
> >
> > --
> > Technical Director
> > Unknown Worlds Entertainment
> > http://www.unknownworlds.com
> >
> >
> > On Tue, Aug 31, 2010 at 6:00 PM, Max McGuire <[email protected]>
> > wrote:
> >         I've run into some unexpected behavior with the __finalize
> >         method. Specifically if my class has members that are also
> >         classes, the __finalize methods for the members are getting
> >         called before the __finalize method for the owner.
> >
> >         Here's a simple example:
> >
> >         class 'B'
> >
> >         function B:__finalize()
> >             print("B:__finalize\n")
> >         end
> >
> >         class 'A'
> >
> >         function A:__init()
> >             self.b = B()
> >         end
> >
> >         function A:__finalize()
> >             print("A:__finalize\n")
> >         end
> >
> >         local a = A()
> >         a = nil
> >
> >         collectgarbage("collect")
> >
> >
> >         The output from this program is:
> >
> >         B:__finalize
> >         A:__finalize
> >
> >
> >         This is the opposite behavior that you would get from a C++
> >         program and is problematic, especially if B is actually a
> >         class implemented in C++ and you tried to access b during the
> >         __finalize method for A.
> >
> >         Is this by design or am I missing something?
> >
> >         Thanks,
> >
> >         Max
> >
> >         --
> >         Technical Director
> >         Unknown Worlds Entertainment
> >         http://www.unknownworlds.com
> >
> >
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