Re: [boost] boost::python: implementation of static data members

From: David Abrahams (david.abrahams_at_[hidden])
Date: 2001-12-02 21:24:46

Scott,

Thanks very much for your patches. At first glance they look good. There are
a few things that need to be done to make them complete patches for the
library:

1. Patches for libs/python/test/comprehensive.cpp and
libs/python/test/comprehensive.py to test the new features
2. Patches for the Boost.Python documentation to advertise them ;-)

I'll be happy to work with you to get these things done.

Also, it looks like the static member accessor patch should really also
patch the getattr/setattr capabilities of the object's extension_class,
don't you think?

-Dave

----- Original Message -----
From: "scott snyder" <snyder_at_[hidden]>
To: <boost_at_[hidden]>
Sent: Sunday, December 02, 2001 7:55 PM
Subject: [boost] boost::python: implementation of static data members

>
> hi -
>
> Here are some patches to boost::python (against boost 1.25.1)
> to better implement static class data members.
>
> With these changes, the following works:
>
> class T
> {
> public:
>   static int x;
> };
>
> ...
>
>   this_class.def_read_write (&T::x, "x");
>
> sss
>
> --- boost/python/detail/extension_class.hpp-orig2 Sat Dec  1 01:10:16 2001
> +++ boost/python/detail/extension_class.hpp Sat Dec  1 01:17:32 2001
> @@ -532,6 +532,15 @@
>          this->add_getter_method(new getter_function<T, MemberType>(pm),
name);
>      }
>
> +    // Provide a function which implements x.<name>, reading from the
given
> +    // static member (pm) of the T class
> +    template <class MemberType>
> +    inline void def_getter(MemberType *pm, const char* name)
> +    {
> +        this->add_getter_method(new
static_getter_function<MemberType>(pm),
> +                                name);
> +    }
> +
>      // Provide a function which implements assignment to x.<name>,
writing to
>      // the given member (pm) of the T obj
>      template <class MemberType>
> @@ -540,6 +549,15 @@
>          this->add_setter_method(new setter_function<T, MemberType>(pm),
name);
>      }
>
> +    // Provide a function which implements assignment to x.<name>,
writing to
> +    // the given static member (pm) of the T class
> +    template <class MemberType>
> +    inline void def_setter(MemberType *pm, const char* name)
> +    {
> +        this->add_setter_method(new
static_setter_function<MemberType>(pm),
> +                                name);
> +    }
> +
>      // Expose the given member (pm) of the T obj as a read-only attribute
>      template <class MemberType>
>      inline void def_readonly(MemberType T::*pm, const char* name)
> @@ -547,6 +565,15 @@
>          this->add_setter_method(new read_only_setattr_function(name),
name);
>          this->def_getter(pm, name);
>      }
> +
> +    // Expose the given static member (pm) of the T class
> +    // as a read-only attribute
> +    template <class MemberType>
> +    inline void def_readonly(MemberType *pm, const char* name)
> +    {
> +        this->add_setter_method(new read_only_setattr_function(name),
name);
> +        this->def_getter(pm, name);
> +    }
>
>      // Expose the given member (pm) of the T obj as a read/write
attribute
>      template <class MemberType>
> @@ -554,6 +581,15 @@
>      {
>          this->def_getter(pm, name);
>          this->def_setter(pm, name);
> +    }
> +
> +    // Expose the given static member (pm) of the T class
> +    // as a read/write attribute
> +    template <class MemberType>
> +    inline void def_read_write(MemberType *pm, const char* name)
> +    {
> +        this->def_getter(pm, name);
> +        this->def_setter(pm, name);
>      }
>
>      // define the standard coercion needed for operator overloading
> --- boost/python/detail/functions.hpp-orig Fri Nov 30 19:14:24 2001
> +++ boost/python/detail/functions.hpp Sat Dec  1 02:25:03 2001
> @@ -288,6 +288,43 @@
>      return none();
>  }
>
> +// Same, for static members/variables.
> +template <class MemberType>
> +class static_getter_function : public function
> +{
> + public:
> +    typedef MemberType* pointer_to_member;
> +
> +    static_getter_function(pointer_to_member pm)
> +        : m_pm(pm) {}
> +
> + private:
> +    PyObject* do_call(PyObject* args, PyObject* keywords) const;
> +
> +    const char* description() const
> +        { return typeid(MemberType (*)()).name(); }
> + private:
> +    pointer_to_member m_pm;
> +};
> +
> +template <class MemberType>
> +class static_setter_function : public function
> +{
> + public:
> +    typedef MemberType* pointer_to_member;
> +
> +    static_setter_function(pointer_to_member pm)
> +        : m_pm(pm) {}
> +
> + private:
> +    PyObject* do_call(PyObject* args, PyObject* keywords) const;
> +
> +    const char* description() const
> +        { return typeid(void (*)(const MemberType&)).name(); }
> + private:
> +    pointer_to_member m_pm;
> +};
> +
>  template <class T, class R, class V, class D>
>  PyObject* virtual_function<T,R,V,D>::do_call(PyObject* args, PyObject*
keywords) const
>  {
> @@ -306,6 +343,30 @@
>      return caller<R>::call(m_default_implementation, args, keywords);
>  }
>
> +template <class MemberType>
> +PyObject* static_getter_function<MemberType>::do_call(
> +    PyObject* args, PyObject* /* keywords */) const
> +{
> +    if (!PyArg_ParseTuple(args, const_cast<char*>("")))
> +        return 0;
> +
> +    return to_python(*m_pm);
> +}
> +
> +template <class MemberType>
> +PyObject* static_setter_function<MemberType>::do_call(
> +    PyObject* args, PyObject* /* keywords */) const
> +{
> +    PyObject* value;
> +    if (!PyArg_ParseTuple(args, const_cast<char*>("O"), &value))
> +        return 0;
> +
> +    typedef typename boost::call_traits<MemberType>::const_reference
extract_type;
> +    *m_pm = from_python(value, type<extract_type>());
> +
> +    return none();
> +}
> +
>  }}} // namespace boost::python::detail
>
>  #endif // FUNCTIONS_DWA051400_H_
> --- libs/python/src/classes.cpp-orig2 Sat Dec  1 02:04:36 2001
> +++ libs/python/src/classes.cpp Sat Dec  1 02:36:47 2001
> @@ -213,6 +213,14 @@
>        if (local_attribute.get())
>            return local_attribute.release();
>
> +      // Check for __getattr__name__
> +      PyErr_Clear ();
> +      const string specific_getattr_name(detail::getattr_string() + name
+ "__");
> +      ref getattr_method = m_name_space.get_item
(specific_getattr_name.reference());
> +      if (getattr_method.get() != 0) {
> +        return PyEval_CallFunction (getattr_method.get(), "()");
> +      }
> +
>        // In case there are no bases...
>        PyErr_SetString(PyExc_AttributeError, name);
>
> @@ -275,6 +283,13 @@
>            throw error_already_set();
>        }
>
> +      const string specific_method_name(detail::setattr_string() + name +
"__");
> +      ref setattr_method = m_name_space.get_item
(specific_method_name.reference());
> +      if (setattr_method.get() != 0) {
> +        ref res (PyEval_CallFunction (setattr_method.get(), "(O)",
value));
> +        return res.get() == 0;
> +      }
> +
>        if (PyCallable_Check(value))
>            detail::enable_named_method(this, name);
>
>
>
> Info: http://www.boost.org  Unsubscribe:
<mailto:boost-unsubscribe_at_[hidden]>
>
> Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
>
>