Re: [Boost-bugs] [Boost C++ Libraries] #9058: with_lock_guard function

Subject: Re: [Boost-bugs] [Boost C++ Libraries] #9058: with_lock_guard function
From: Boost C++ Libraries (noreply_at_[hidden])
Date: 2013-09-01 10:56:44

#9058: with_lock_guard function
-------------------------------+----------------------
  Reporter:  ruslan_baratov@…  |      Owner:  viboes
      Type:  Feature Requests  |     Status:  assigned
 Milestone:  To Be Determined  |  Component:  thread
   Version:  Boost 1.54.0      |   Severity:  Problem
Resolution:                    |   Keywords:
-------------------------------+----------------------

Comment (by ruslan_baratov@…):

 Updated version on github:
 {{{
   github.com/ruslo/thread/commit/ea30f0dc6b1fe7951d1d0dff88fd03e946429669
 }}}

 For function without c++11 variadic templates, Func parameter is now
 movable:

 {{{
 template <class Lockable, class Func, class Arg>
 typename boost::result_of<Func(Arg)>::type with_lock_guard(
     Lockable& m,
     BOOST_FWD_REF(Func) func,
     BOOST_FWD_REF(Arg) arg
 ) {
   boost::lock_guard<Lockable> lock(m);
   return func(
       boost::forward<Arg>(arg)
   );
 }
 }}}

 overloaded version for function pointers:

 {{{
 template <class Lockable, class Func, class Arg1, class Arg2>
 typename boost::result_of<
     typename boost::add_pointer<Func>::type(Arg1, Arg2)
 >::type with_lock_guard(
     Lockable& m,
     Func* func,
     BOOST_FWD_REF(Arg1) arg1,
     BOOST_FWD_REF(Arg2) arg2
 ) {
   BOOST_STATIC_ASSERT(boost::is_function<Func>::value);

   boost::lock_guard<Lockable> lock(m);
   return func(
       boost::forward<Arg1>(arg1),
       boost::forward<Arg2>(arg2)
   );
 }
 }}}

 In this version boost::bind which call non-const class method still not
 working (for variadic template
 version is OK). It's because BOOST_FWD_REF(Func) = const Func&. I can't
 figure out how to do
 a workaround in not ugly way. I can make version with copy-by-value for
 types with T::result_type defined if this is appropriate.

 If used with lambda, BOOST_RESULT_OF_USE_DECLTYPE may need to be defined,
 see this bug: https://svn.boost.org/trac/boost/ticket/7311


 I've added test:
 {{{
   test_with_lock_guard_bind.cpp
   test_with_lock_guard_lambda.cpp
   test_with_lock_guard_move.cpp
   test_with_lock_guard_simple.cpp
 }}}

 Replying to [comment:10 viboes]:
 > The C++11 definition must be protected also with no rvalue references
 and no decltype.
 I've add BOOST_NO_CXX11_DECLTYPE check; do
 BOOST_NO_CXX11_RVALUE_REFERENCES check really needed? I thought it
 automatically checked in BOOST_FWD_REF (?)

-- 
Ticket URL: <https://svn.boost.org/trac/boost/ticket/9058#comment:11>
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