[boost] [locale] localization_backend_manager interface issue

Subject: [boost] [locale] localization_backend_manager interface issue
From: Max Sobolev (macsmr_at_[hidden])
Date: 2011-04-15 06:55:25

> std::auto_ptr<localization_backend>
>       localization_backend_manager::get() const;

Class localization_backend_manager is marked as BOOST_LOCALE_DECL. This 
is hinting at placing instances of the class in a standalone shared 
library without problems. But here it is: using std::auto_ptr<> in 
interfaces is an error (Due to possibility of placing instances of 
classes in dynamic libraries).

Dynamic library that contain your class might be compiled in debug / 
release / another mode, but client's code might have an alternative heap 
(because it use another C++ Run Time system) with an alternative heap 
manager. std::auto_ptr<> doesn't carrying *deleter* with a raw pointer 
of the allocated object, as boost::scoped_ptr<>, boost::shared_ptr<> or 
c++0x's std::unique_ptr<> does. Memory  allocated from one heap might be 
"released" by foreign heap manager! :-/

See Sutter/Alexandrescu recommendation do not use std::auto_ptr<> (in 
ISBN: 9780321113580, C++ Coding Standards, "Rule 60: Avoid allocating 
and deallocating memory in different modules") and problem description 
(in ISBN: 9780201604641, Douglas Schmidt, Stephen Huston - C++ Network 
Programming [Volume 2] Chapter 5, "Sidebar 29: Portable Heap Operations 
with ACE")

..so change std::auto_ptr<> to some of the more safe smart pointer.

> void localization_backend_manager::select(
>                    std::string const& backend_name,
>                    locale_category_type category = all_categories);

Why you don't use enums instead of std::string and locale_category_type? 
(latter is unsigned, actually). So this code is permissible:

boost::locale::localization_backend_manager::global().select("...",
                                     static_cast<unsigned>(std::rand()));

std::string as opposed to ((emulated) scoped) enum implies discarded 
static type checking plus run-time overhead (due to *run-time* "type" 
checking, as i guess). unsigned type provides a wider "supertype" for 
argument than necessary

-- 
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