ceph/src/boost/libs/python/doc/reference/args.qbk

   1 [section boost/python/args.hpp]
   2 [section Introduction]
   3 Supplies a family of overloaded functions for specifying argument keywords for wrapped C++ functions.
   4 [section keyword-expressions]
   5 A keyword-expression results in an object which holds a sequence of [link ntbs]\ es, and whose type encodes the number of keywords specified. The keyword-expression may contain default values for some or all of the keywords it holds
   6 [endsect]
   7 [endsect]
   8 [section Class `arg`]
   9 The objects of class arg are keyword-expressions holding one keyword ( size one )
  10 ``
  11 namespace boost { namespace python
  12 {
  13         struct arg
  14         {
  15           template <class T>
  16                   arg &operator = (T const &value);
  17           explicit arg (char const *name){elements[0].name = name;}
  18         };
  19
  20 }}
  21 ``
  22 [endsect]
  23 [section Class `arg` constructor]
  24 ``arg(char const* name);``
  25 [variablelist
  26 [[Requires][The argument must be a [link ntbs].]]
  27 [[Effects][Constructs an arg object holding a keyword with name name.]]
  28 ]
  29 [endsect]
  30 [section Class `arg` operator=]
  31 ``template <class T> arg &operator = (T const &value);``
  32 [variablelist
  33 [[Requires][The argument must convertible to python.]]
  34 [[Effects][Assigns default value for the keyword.]]
  35 [[Returns][Reference to `this`.]]
  36 ]
  37 [endsect]
  38 [section Keyword-expression operator,]
  39 ``
  40 keyword-expression operator , (keyword-expression, const arg &kw) const
  41 keyword-expression operator , (keyword-expression, const char *name) const;
  42 ``
  43 [variablelist
  44 [[Requires][The argument name must be a [link ntbs].]]
  45 [[Effects][Extends the keyword-expression argument with one more keyword.]]
  46 [[Returns][The extended keyword-expression.]]
  47 ]
  48 [endsect]
  49 [section Example]
  50 ``
  51 #include <boost/python/def.hpp>
  52 using namespace boost::python;
  53
  54 int f(double x, double y, double z=0.0, double w=1.0);
  55
  56 BOOST_PYTHON_MODULE(xxx)
  57 {
  58   def("f", f, (arg("x"), "y", arg("z")=0.0, arg("w")=1.0));
  59 }
  60 ``
  61 [endsect]
  62 [endsect]