[Boost-bugs] [Boost C++ Libraries] #3653: converter collisions behave differently debug|release

Subject: [Boost-bugs] [Boost C++ Libraries] #3653: converter collisions behave differently debug|release
From: Boost C++ Libraries (noreply_at_[hidden])
Date: 2009-11-20 21:02:41

#3653: converter collisions behave differently debug|release
--------------------------+-------------------------------------------------
 Reporter:  troy          |       Owner:  dave   
     Type:  Bugs          |      Status:  new    
Milestone:  Boost 1.42.0  |   Component:  Python 
  Version:  Boost 1.41.0  |    Severity:  Problem
 Keywords:                |  
--------------------------+-------------------------------------------------
 from a thread on the c++-sig list titled "dynamic compile and to-Python
 converter..."

 The 'worst' and most common scenario is, precisely put:  more than one
 python extension module over which we have no control has wrapped type T.
 We need to use them simultaneously.  For instance, here are two modules
 that both wrap vector<double>. With assertions enabled, this happens:

 >>> import converter_collisions1_ext
 >>> import converter_collisions2_ext
 python:
 /home/troy/Projects/boost/src/libs/python/src/converter/registry.cpp:212:
 void boost::python::converter::registry::insert(PyObject* (*)(const
 void*), boost::python::type_info, const PyTypeObject* (*)()): Assertion
 `slot->m_to_python == 0' failed.
 zsh: abort      python


 delightfully, without assertions there is only a warning:


 >>> import converter_collisions1_ext
 >>> import converter_collisions2_ext
 __main__:1: RuntimeWarning: to-Python converter for std::vector<double,
 std::allocator<double> > already registered; second conversion method
 ignored.


 So one resolution is to remove the 'assert' that triggers this crash and
 leave the semantics as-is:  second and later converter registrations are
 warned about and ignored.   I'm simply suggesting we give the user more
 control over this behavior, because in a number of situations (it is up to
 the user to determine what they are) such control would be useful.

-- 
Ticket URL: <https://svn.boost.org/trac/boost/ticket/3653>
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