Re: double deletion problem with shared pointers.

Nigel Atkinson wrote:
> The attached code shows the double deletion problem I encounted.  I
> previously thought that the problem only surfaced when using the
> shared_ptr_converter.  However it looks like it happens either way.

Right. This fails because the widget_wrapper instance that corresponds
to your Lua widget instance is held in a global shared_ptr, which is
destructed after the Lua state is destroyed.

widget_wrapper will hold a weak back reference to the Lua instance, so
that it can call back to overridden functions in Lua. When it is
destructed it will clean up the weak reference, and in this case that
means accessing a destroyed Lua state.

shared_ptr_converter has the same problem. It stores a back reference to
the Lua instance, keeping it alive so that you don't get the slicing you
encountered, and when it's destructed it cleans that up.

AFAIK there's really no way around this. You need to ensure that you
don't destroy the Lua state while you still have references to Lua
objects around.

-- 
Daniel Wallin
BoostPro Computing
http://www.boostpro.com

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