def.qbk 3.3 KB

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  1. [section boost/python/def.hpp]
  2. [section Introduction]
  3. `def()` is the function which can be used to expose C++ functions and callable objects as Python functions in the [link high_level_components.boost_python_scope_hpp.introduction current scope].
  4. [endsect]
  5. [section Functions]
  6. ``
  7. template <class F>
  8. void def(char const* name, F f);
  9. template <class Fn, class A1>
  10. void def(char const* name, Fn fn, A1 const&);
  11. template <class Fn, class A1, class A2>
  12. void def(char const* name, Fn fn, A1 const&, A2 const&);
  13. template <class Fn, class A1, class A2, class A3>
  14. void def(char const* name, Fn fn, A1 const&, A2 const&, A3 const&);
  15. ``
  16. [variablelist
  17. [[Requires][name is an [link ntbs] which conforms to Python's [@http://www.python.org/doc/current/ref/identifiers.html identifier naming rules].
  18. * If `Fn` is [derived from] [link object_wrappers.boost_python_object_hpp.class_object object], it will be added to the [link high_level_components.boost_python_scope_hpp.introduction current scope] as a single overload. To be useful, `fn` should be [@http://www.python.org/doc/current/lib/built-in-funcs.html#l2h-6 callable].
  19. * If `a1` is the result of an [link function_invocation_and_creation.boost_python_overloads_hpp.introduction.overload_dispatch_expressions overload-dispatch-expression], only the second form is allowed and `fn` must be a pointer to function or pointer to member function whose [link arity] is the same as A1's [link function_invocation_and_creation.boost_python_overloads_hpp.introduction.overload_dispatch_expressions maximum arity].
  20. [*Effects:] For each prefix `P` of `Fn`\ 's sequence of argument types, beginning with the one whose length is `A1`\ 's [link function_invocation_and_creation.boost_python_overloads_hpp.introduction.overload_dispatch_expressions minimum arity], adds a `name(...)` function overload to the [link high_level_components.boost_python_scope_hpp.introduction current scope]. Each overload generated invokes a1's call-expression with P, using a copy of a1's call policies. If the longest valid prefix of A1 contains N types and a1 holds M keywords, an initial sequence of the keywords are used for all but the first N - M arguments of each overload.
  21. * Otherwise, fn must be a non-null function or member function pointer, and a single function overload built around fn is added to the current scope. If any of a1-a3 are supplied, they may be selected in any order from the table below.
  22. [table
  23. [[Mnemonic Name][Requirements/Type properties][Effects]]
  24. [[docstring][Any [link ntbs]][Value will be bound to the `__doc__` attribute of the resulting method overload.]]
  25. [[policies][A model of [link concepts.callpolicies CallPolicies]][A copy will be used as the call policies of the resulting method overload.]]
  26. [[keywords][The result of a [link function_invocation_and_creation.boost_python_args_hpp.introduction.keyword_expressions keyword-expression] specifying no more arguments than the [link arity] of `fn`.][A copy will be used as the call policies of the resulting method overload.]]
  27. ]
  28. ]]
  29. ]
  30. [endsect]
  31. [section Example]
  32. ``
  33. #include <boost/python/def.hpp>
  34. #include <boost/python/module.hpp>
  35. #include <boost/python/args.hpp>
  36. using namespace boost::python;
  37. char const* foo(int x, int y) { return "foo"; }
  38. BOOST_PYTHON_MODULE(def_test)
  39. {
  40. def("foo", foo, args("x", "y"), "foo's docstring");
  41. }
  42. ``
  43. [endsect]
  44. [endsect]