Thorsten Schöning created LOGCXX-486:
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             Summary: Replace ObjectPtr with more standard shared_ptr.
                 Key: LOGCXX-486
                 URL: https://issues.apache.org/jira/browse/LOGCXX-486
             Project: Log4cxx
          Issue Type: Bug
          Components: Core
    Affects Versions: 0.11.0
            Reporter: Thorsten Schöning
             Fix For: 0.12.0


To fix memory leaks in Levels in LOGCXX-485, we decided to change the API in 
back incompatible way and don't use LevelPtr anymore at all. If such a change 
is already made, this might be the best time to additionally remove ObjectPtr 
in favour of a more standard shared_ptr as well. In the end, the leak with 
Levels shouldn't have happened, because LevelPtr is a ObjectPtr and should take 
care of deleting allocated memory itself properly. Additionally, shared_ptrs in 
various implementations are really common these days, so there shouldn't be a 
need for a custom implementation anymore.

So which shared_ptr to use? I suggest focussing on std with C++11 and boost as 
a fallback for all users with older compilers and environments. We should 
create some kind of macro to make switching between both easy using some define 
and std might be a reasonable choice as default without any switch. This way 
modern C++ environments don't introduce additional requirements. My own 
compiler C++Builder XE10 from embarcadero e.g. is providing Boost 1.39 for its 
legacy compiler, which not yet supports C++11 very well. The newer CLANG based 
ones on the other hand don't fully support some older legacy projects and libs, 
so supporting a Boost fallback should be a reasonable choice to not need to 
deal with a custom implementation. Boost itself should be so widespread used 
these days and 1.39 providing shared_ptr is so old, that it is most likely that 
all users of log4cxx can support it.

The following was suggested on the mailing list as an example to switch between 
both:

http://stackoverflow.com/questions/7095556/how-to-handle-evolving-c-std-namespace-e-g-stdtr1shared-ptr-vs-std

But I suggest not relying on autoconf anymore. We had quite some build tool 
discussions in the past, CMAKE has often been named as an alternative. It 
should be the easiest to simply define some macro which decides about the 
namespace to use, so the user can switch between boost and std or even std::tr1 
and such manually by simply defining the macro. If it's undefined at compile 
time, std might be used as a fallback.

This has been discussed in the following thread:

http://mail-archives.apache.org/mod_mbox/logging-log4cxx-user/201610.mbox/<516ac3df-9119-3dc0-b7c7-5eba797a4ea5%40visualact.se>



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