Re: [Boost-users] Interprocess: limited boost::any in shared memory

Subject: Re: [Boost-users] Interprocess: limited boost::any in shared memory
From: Ferguson, Neil D CTR (US) (neil.d.ferguson.ctr_at_[hidden])
Date: 2018-11-26 14:43:17

Mr. de Vries,
std::variant looks like it should work splendidly.  boost::variant might be even better.  Thank you.
BTW:  this is my first user group interaction; I hope I am responding correctly.
Neil Ferguson
  

-----Original Message-----
From: Maarten de Vries [mailto:maarten_at_[hidden]] 
Sent: Wednesday, November 21, 2018 1:06 PM
To: boost-users_at_[hidden]
Cc: Ferguson, Neil D CTR (US) <neil.d.ferguson.ctr_at_[hidden]>
Subject: [Non-DoD Source] Re: [Boost-users] Interprocess: limited boost::any in shared memory

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On Wed, 21 Nov 2018 at 20:58, Ferguson, Neil D CTR (US) via Boost-users <boost-users_at_[hidden] < Caution-mailto:boost-users_at_[hidden] > > wrote:


        Sirs and madams,
        I hope to use boost interprocess shared memory to pass complex and dynamic data structures between processes on a host efficiently.  The structures will be comprised only of simple primitives (int, float, etc.), interprocess basic_string,  interprocess containers (vectors and maps), containers of containers, and (possible deal killer) boost::any.  From the interprocess documentation, it _looks_ like the preceding is doable, aside from boost::any.  The boost::any objects will themselves contain only primitives, basic_string, or interprocess vectors of unsigned char.    So it _looks_ like the data held by the any should be okay.  My question:  does boost::any use pointers, references, or other constructs that preclude the class from working in shared memory?
        Thanks for your advice.
        Neil Ferguson
        


Take a look at /usr/include/boost/any.hpp . You will see that the actual content of the any object is a pointer created with `new` and cleaned up with `delete`. So this will not work properly in shared memory.

You could consider using std::variant instead, which does not put storage on the heap (unless contained objects do it themselves, of course).

Kind regards,
Maarten de Vries