Re: [C++-sig] How to get items from a tuple
Thank you, but I had tried that and it doesn't seem to work... look: http://codepad.org/kA61P8r0 What am I doing wrong? Thanks, Ricardo Abreu David Abrahams wrote: on Thu Jan 15 2009, Ricardo Abreu wrote: Hello, How do I extract elements from a tuple that I receive from python? boost::python::tuple doesn't seem to have anything for that in its interface... t[n] is the nth element of tuple t. ___ Cplusplus-sig mailing list Cplusplus-sig@python.org http://mail.python.org/mailman/listinfo/cplusplus-sig
Re: [C++-sig] How to get items from a tuple
Ricardo Abreu wrote: Thank you, but I had tried that and it doesn't seem to work... look: http://codepad.org/kA61P8r0 What am I doing wrong? In the sake of understanding the code a little better you may write it a bit less compact. Then you will realize that the item extraction you were asking about is in fact working fine. However, as it returns an object, not an int, you still need to extract the C++ type properly. Just using C casts doesn't work. (Read the docs.) Regards, Stefan -- ...ich hab' noch einen Koffer in Berlin... ___ Cplusplus-sig mailing list Cplusplus-sig@python.org http://mail.python.org/mailman/listinfo/cplusplus-sig
Re: [C++-sig] How to get items from a tuple
Well, thank you. The problem was really that I didn't notice I had to extract the int explicitly. About the code being too compact, I'm not sure I got what you mean, unless you would want me to have a variable in between the tuple and the print just to hold the result of the cast, in which case I don't agree you would gain on readability - you would see a cleaner print but you would have to track another variable, and I really don't think that (int)t[0] is that difficult to understand. Anyway, thanks again, Ricardo ___ Cplusplus-sig mailing list Cplusplus-sig@python.org http://mail.python.org/mailman/listinfo/cplusplus-sig
Re: [C++-sig] How to get items from a tuple
Ricardo Abreu wrote: Well, thank you. The problem was really that I didn't notice I had to extract the int explicitly. About the code being too compact, I'm not sure I got what you mean, unless you would want me to have a variable in between the tuple and the print just to hold the result of the cast, in which case I don't agree you would gain on readability - you would see a cleaner print but you would have to track another variable, and I really don't think that (int)t[0] is that difficult to understand. I'm not saying the code itself is too compact. My point was that often there is a lot going on in the evaluation of a single expression. As long as all works fine, that's good, but when something fails it might be a good idea to dissect the statement to see what is actually happening, step by step. Regards, Stefan -- ...ich hab' noch einen Koffer in Berlin... ___ Cplusplus-sig mailing list Cplusplus-sig@python.org http://mail.python.org/mailman/listinfo/cplusplus-sig
Re: [C++-sig] py++ with template member function of template class
Roman Yakovenko gmail.com> writes:
> > /
> > // test template member function in template class
> > // THIS WON'T WORK!
> > template
> > class BFunc
> > {
> > public:
> > template
> > T foo(const T& t) const;
> > };
> >
> > template template
> > T BFunc::foo(const T& t) const { return t + 1; };
> >
>
> Unfortunately GCC-XML doesn't dump the information. I am also not
> aware of any workaround .
>
> You will have to create the code by yourself. Py++ allows you to
> integrate your code easily(
> http://language-binding.net/pyplusplus/documentation/inserting_code.html
> )
In this mail
http://www.mail-archive.com/gcc...@gccxml.org/msg00316.html
Brad King, author of gccxml, confirms that this isn't implemented.
I hope as gccxml gets more and more popular (i.e. the CERN started using it to
get C++ reflection) someone will continue Brads good work. He stated in the
mail that he is willing to help get people started.
-- Maik
___
Cplusplus-sig mailing list
Cplusplus-sig@python.org
http://mail.python.org/mailman/listinfo/cplusplus-sig
Re: [C++-sig] can boost::python class imlement buffer protocol?
Neal Becker wrote:
> David Abrahams wrote:
>
>>
>> on Wed Jan 07 2009, Neal Becker wrote:
>>
>>> This would require filling in tp_as_buffer field in the PyTypeObject
>>> structure for the
>>> class. Is this possible? Any clue how/where this could be done?
>>
>> I honestly don't know the answers to these questions, sorry.
>>
>
> As a workaround, I currently implemented an 'as_buffer' member function.
> For example:
>
> template
> inline object as_buffer (ublas::vector & m) {
> return object (handle<> (PyBuffer_FromReadWriteMemory
> ((void*)(&m.data()[0]), m.size()*sizeof(T;
> }
Actually, this isn't all that useful. The problem is, you want to use
with_custodian_and_ward_postcall<0,1> on this. But you can't because buffer
object doesn't support weak references. So while the above can provide a
buffer interface, it has no idea of lifetime management.
I wonder whether python buffer object could be made to support weak refs? Of
course, if there was really a way to add a buffer interface to my
boost::python object that would be even better.
___
Cplusplus-sig mailing list
Cplusplus-sig@python.org
http://mail.python.org/mailman/listinfo/cplusplus-sig
