Re: [boost] Boost.Python question about converters and make_getter

Subject: Re: [boost] Boost.Python question about converters and make_getter
From: Ralf W. Grosse-Kunstleve (rwgk_at_[hidden])
Date: 2009-11-21 10:02:37

I think this is covered by

http://www.boost.org/doc/libs/1_40_0/libs/python/doc/v2/faq.html#topythonconversionfailed

----- Original Message ----
From: John Wiegley <jwiegley_at_[hidden]>
To: boost_at_[hidden]
Sent: Fri, November 20, 2009 2:55:04 AM
Subject: [boost] Boost.Python question about converters and make_getter

I have a converter registered for a boost::optional<amount_t> object.  If I use it as follows, my code works just fine:

  boost::optional<amount_t> py_price(annotation_t& ann) {
    return ann.price;
  }

  class_< annotation_t > ("Annotation")
    .add_property("price", py_price)
    ;

However, if I dispense with the intermediary and use make_getter, I get an exception stating that no conversion exists for optional<amount_t>:

  class_< annotation_t > ("Annotation")
    .add_property("price", make_getter(&annotation_t::price))
    ;

The attached file demonstrates this bug using Boost 1.40 and Python 2.6.1.  I'm running it on OS X 10.6.2 with g++ 4.4.2.  My steps were:

g++-mp-4.4 -I/usr/include/python2.6 -I/usr/local/include/boost-1_40 -o bug.so bug.cc -L/usr/local/lib -lboost_python-xgcc44-d-1_40 -lpython -shared

$ python
>>> import bug
>>> x = bug.Annotation()
>>> x.price2
# This works just fine
>>> x.price
# This causes an abort() due to terminate()

John