Re: [Boost-bugs] [Boost C++ Libraries] #2049: extracting c++ pointer from python object with multiple parents

Subject: Re: [Boost-bugs] [Boost C++ Libraries] #2049: extracting c++ pointer from python object with multiple parents
From: Boost C++ Libraries (noreply_at_[hidden])
Date: 2008-06-26 14:56:35

#2049: extracting c++ pointer from python object with multiple parents
-----------------------------------+----------------------------------------
  Reporter:  bloodyfanatic_at_[hidden]  |       Owner:  dave   
      Type:  Bugs                  |      Status:  closed 
 Milestone:  Boost 1.35.1          |   Component:  Python 
   Version:  Boost 1.35.0          |    Severity:  Problem
Resolution:  invalid               |    Keywords:         
-----------------------------------+----------------------------------------
Comment (by anonymous):

 Replying to [comment:3 dave]:
 > Replying to [comment:2 bloodyfanatic_at_[hidden]]:
 > > Replying to [comment:1 dave]:
 > > > Does this fail even when the dtors are non-virtual?
 > >
 > > yes it does, with the same error as always:
 >
 > In that case, please post the ''fully reduced'' test case
 >
 > Also, you need an __init__ method in both1 and both2 that initializes
 *both* bases or this can never work, because a wrapped class' __init__
 function is what actually constructs the C++ base object.  Without it,
 there is no base object to which a pointer can be returned from
 {{{extract}}}:
 > {{{
 >   def __init__(self):
 >      Base1.__init__(self)
 >      Base2.__init__(self)
 > }}}
 > I don't know how to do this properly with super (the technique Stefan
 was suggesting), but his suggestion as written didn't take care of both
 bases, as the following demonstrates:
 >
 > {{{
 > #!python
 > >>> class X(object):
 > ...    def __init__(self):
 > ...        print 'X'
 > ...
 > >>> class Y(object):
 > ...     def __init__(self):
 > ...         print 'Y'
 > ...
 > >>> class Z(X,Y): pass  # essentially what you posted
 > ...
 > >>> z = Z()
 > X
 > >>> class Z(X,Y):
 > ...     def __init__(self):
 > ...         super(Z,self).__init__()  # Stefan's suggestion
 > ...
 > >>> z = Z()
 > X
 > >>> class Z(X,Y):
 > ...     def __init__(self):
 > ...         X.__init__(self)
 > ...         Y.__init__(self)
 > ...
 > >>> z = Z()
 > X
 > Y
 > >>>
 > }}}
 >
 > I'm pretty sure this solves your problem so I'm closing the ticket, but
 if it doesn't, please re-open it.

 just tested that and it works. Thank you very much :)

-- 
Ticket URL: <http://svn.boost.org/trac/boost/ticket/2049#comment:4>
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