Bug#523344: boost.python: add support for calling methods with both variable arguments and keywords

[Anderson Lizardo]

Package: boost1.38
Version: 1.38.0-3
Tags: patch

This patch for this is on the boost trunk already:
https://svn.boost.org/trac/boost/changeset/47846

According to the commiter of the patch (contacted privately), it was
supposed to be included in the 1.38.0 release, but due to some release
management mistake, it was not merged to the 1.38.x release branch.

If you look at the patch, the changes are very simple (only changes a
single header, updates the documentation and adds tests for the
feature), and should not break anything, just add the necessary
feature.

For convenience, I attached to this report the patch downloaded from
the URL above (converted to Unix end-of-line, because trac generates
DOS formatted diffs).

Index: /trunk/boost/python/object_core.hpp
===================================================================
--- /trunk/boost/python/object_core.hpp (revision 45918)
+++ /trunk/boost/python/object_core.hpp (revision 47846)
@@ -42,4 +42,10 @@
 
 namespace boost { namespace python { 
+
+namespace detail
+{
+  class kwds_proxy; 
+  class args_proxy; 
+} 
 
 namespace converter
@@ -103,4 +109,9 @@
 # define BOOST_PP_ITERATION_PARAMS_1 (3, (1, BOOST_PYTHON_MAX_ARITY, <boost/python/object_call.hpp>))
 # include BOOST_PP_ITERATE()
+    
+      detail::args_proxy operator* () const; 
+      object operator()(detail::args_proxy const &args) const; 
+      object operator()(detail::args_proxy const &args, 
+                        detail::kwds_proxy const &kwds) const; 
 
       // truth value testing
@@ -417,4 +428,60 @@
 //
 
+namespace detail 
+{
+
+class call_proxy 
+{ 
+public: 
+  call_proxy(object target) : m_target(target) {} 
+  operator object() const { return m_target;} 
+ 
+ private: 
+    object m_target; 
+}; 
+ 
+class kwds_proxy : public call_proxy 
+{ 
+public: 
+  kwds_proxy(object o = object()) : call_proxy(o) {} 
+}; 
+class args_proxy : public call_proxy 
+{ 
+public: 
+  args_proxy(object o) : call_proxy(o) {} 
+  kwds_proxy operator* () const { return kwds_proxy(*this);} 
+}; 
+} 
+ 
+template <typename U> 
+detail::args_proxy api::object_operators<U>::operator* () const 
+{ 
+  object_cref2 x = *static_cast<U const*>(this); 
+  return detail::args_proxy(x); 
+} 
+ 
+template <typename U> 
+object api::object_operators<U>::operator()(detail::args_proxy const &args) const 
+{ 
+  U const& self = *static_cast<U const*>(this); 
+  PyObject *result = PyObject_Call(get_managed_object(self, tag), 
+                                   args.operator object().ptr(), 
+                                   0); 
+  return object(detail::new_reference(result)); 
+ 
+} 
+ 
+template <typename U> 
+object api::object_operators<U>::operator()(detail::args_proxy const &args, 
+                                            detail::kwds_proxy const &kwds) const 
+{ 
+  U const& self = *static_cast<U const*>(this); 
+  PyObject *result = PyObject_Call(get_managed_object(self, tag), 
+                                   args.operator object().ptr(), 
+                                   kwds.operator object().ptr()); 
+  return object(detail::new_reference(result)); 
+ 
+}  
+
 inline object::object()
     : object_base(python::incref(Py_None))
Index: /trunk/libs/python/test/object.cpp
===================================================================
--- /trunk/libs/python/test/object.cpp (revision 45918)
+++ /trunk/libs/python/test/object.cpp (revision 47846)
@@ -187,4 +187,9 @@
     return s.slice(2,-1).slice(1,-1)  == "lo, wor";
 }
+
+object test_call(object c, object args, object kwds) 
+{ 
+    return c(*args, **kwds); 
+} 
 
 bool check_binary_operators()
@@ -378,4 +383,5 @@
     def("test_not_item", test_not_item);
 
+    def("test_call", test_call);
     def("check_binary_operators", check_binary_operators);
     def("check_inplace", check_inplace);
Index: /trunk/libs/python/test/object.py
===================================================================
--- /trunk/libs/python/test/object.py (revision 45918)
+++ /trunk/libs/python/test/object.py (revision 47846)
@@ -135,5 +135,10 @@
         Operators
 
-        
+>>> def print_args(*args, **kwds): 
+...     print args, kwds 
+>>> test_call(print_args, (0, 1, 2, 3), {'a':'A'}) 
+(0, 1, 2, 3) {'a': 'A'}
+
+
 >>> assert check_binary_operators()
 
Index: /trunk/libs/python/doc/v2/object.html
===================================================================
--- /trunk/libs/python/doc/v2/object.html (revision 45918)
+++ /trunk/libs/python/doc/v2/object.html (revision 47846)
@@ -656,4 +656,9 @@
       object operator()(A0 const&amp;, A1 const&amp;,...An const&amp;) const;
 
+      detail::args_proxy operator* () const; 
+      object operator()(detail::args_proxy const &amp;args) const; 
+      object operator()(detail::args_proxy const &amp;args, 
+                        detail::kwds_proxy const &amp;kwds) const; 
+
       // truth value testing
       //
@@ -705,4 +710,23 @@
       a2,...aN)</dt>
     </dl>
+
+<pre>
+object operator()(detail::args_proxy const &amp;args) const; 
+</pre>
+<dl class="function-semantics">
+  <dt><b>Effects:</b>
+  call object with arguments given by the tuple <varname>args</varname></dt>
+</dl>
+<pre>
+object operator()(detail::args_proxy const &amp;args, 
+                  detail::kwds_proxy const &amp;kwds) const; 
+</pre>
+<dl class="function-semantics">
+  <dt><b>Effects:</b>
+  call object with arguments given by the tuple <varname>args</varname>, and named
+  arguments given by the dictionary <varname>kwds</varname></dt>
+</dl>
+
+
 <pre>
 operator bool_type() const;