Re: [boost] boost::interprocess mixing heap and shared memory ?

Subject: Re: [boost] boost::interprocess mixing heap and shared memory ?
From: Phil Endecott (spam_from_boost_dev_at_[hidden])
Date: 2009-04-11 14:01:07

Oncaphillis wrote:
>   my_map::iterator i = 
>         the_map->find(my_string("BOGUS",my_char_allocator_t(shm)));

>   Is there a way to use heap or stack memory for thinks like that ?

This is an example of a larger problem that has worried me 
occasionally.  For example, say I have a vector of structs sorted 
according to a string member; I might like to write:

   std::vector<my_struct> v;
   std::lower_bound(v.begin(), v.end(), std::string("hello"), COMP());

COMP needs to be a functor that can compare one of my structs with a 
std::string.  That's not a problem, and in fact code like this will 
actually work with some standard libraries.  But the standard requires 
that COMP takes two arguments of the same type, so standard library 
that did more checking would reject it.

With algorithms like std::lower_bound it is of course possible to write 
one's own version that allows this sort of use.  But there is more of a 
problem with member functions like map::find.

Is anyone aware of any rationale for the current requirements?

Phil.