Re: [Boost-users] [Boost::any] Memory management using dynamic libraries

Subject: Re: [Boost-users] [Boost::any] Memory management using dynamic libraries
From: Gavin Lambert (gavinl_at_[hidden])
Date: 2014-01-13 01:32:35

On 27/12/2013 07:27, Quoth Eugenio Bargiacchi:
> However, if my problem can be solved by simply destroying the map
> before unloading all shared libraries, I am content. What I am most
> concerned about is whether every single time a module destroys a value
> it needs to somehow give control back to the module that created it so
> that it can destroy it, or if that is handled automatically when a
> destructor is called.

If the type explicitly defines a non-inline destructor, then it will 
actually call the destructor in the module.  If you use an inline 
destructor or compiler-generated destructor then it might or might not 
depending on how the compiler was feeling at the time.

The peril doesn't end there though.  Even if you guarantee that it will 
call the destructor in the module, two different modules might not have 
the same memory allocator (especially if there's a chance they might be 
compiled with different compilers or even different versions), and weird 
things may happen if you allocate memory in one module and try to 
deallocate it in another.

Some smart pointer objects (eg. shared_ptr) let you provide an explicit 
"deleter" function that gets called when the pointee needs to be 
destroyed, which can help mitigate some cases of objects passing between 
modules.  But there still be dragons.