Gustavo,

I think you win some sort of prize for not only fastest mailing list responses, 
but also fastest implementation of features. I reviewed the diff, and changed 
what I was adding to the global annotations table for these pointers to 
“{‘return_internal_reference’:’true’}” – this seems to be what the new code in 
foo.h was doing.  I am still getting the errors, though – is this the right way 
of using it?

And just to make sure, I grabbed a new checkout of pybindgen and re-installed 
it.

From: cplusplus-sig-bounces+bfitzpatrick=vtiinstruments....@python.org 
[mailto:cplusplus-sig-bounces+bfitzpatrick=vtiinstruments....@python.org] On 
Behalf Of Gustavo Carneiro
Sent: Wednesday, January 20, 2010 1:18 PM
To: Development of Python/C++ integration
Subject: Re: [C++-sig] Boost-python/pybindgen and wrapping member variables


On Wed, Jan 20, 2010 at 5:43 PM, Ben Fitzpatrick 
<bfitzpatr...@vtiinstruments.com<mailto:bfitzpatr...@vtiinstruments.com>> wrote:
Hi everyone,

I think I’m finally getting the hang of this, I seem to have gotten almost 
everything in my project working thanks to Gustavo’s latest pybindgen patch. 
One of the remaining things I am having difficulty with is putting annotations 
on member variables of a class. I have something of the form:

class foo{
 <stuff>
};

class baz {
  public:
  foo* var;
}

The error I am getting from pybindgen is “WrapperWarning: Return value ‘::foo 
*’ error (used in baz::var [variable]): TypeConfigurationError(‘Either 
caller_owns_return or self.reference_existing_object must be given’)

 I know that the issue is that I need to stick an annotation on there. Since 
the pointer is allocated and tracked by the underlying C++ code, I’m pretty 
sure that I need to put reference_existing_object on it. I’ve tried inserting 
“{‘reference_existing_object’ : ‘true’}” into the global_annotations table, and 
also inserting it into the parameter_annotations[“return”] dictionary. For 
kicks, I even tried both at once. No matter what I do I can’t get rid of the 
error, or see it show up in my final build, which leads me to believe there’s 
something I’m missing. I went and looked up the documentation for 
reference_existing_object, but of course none of their examples show how you 
could use it on a member variable. What am I missing?
You are not missing anything.  Annotations for member variables (pybindgen 
calls them "instance attributes") were not implemented.

An oversight easily fixed:

http://bazaar.launchpad.net/~gjc/pybindgen/trunk/revision/742


Thanks,
Ben Fitzpatrick

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--
Gustavo J. A. M. Carneiro
INESC Porto, Telecommunications and Multimedia Unit
"The universe is always one step beyond logic." -- Frank Herbert
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