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`` 7template <class F> 8void def(char const* name, F f); 9 10template <class Fn, class A1> 11void def(char const* name, Fn fn, A1 const&); 12 13template <class Fn, class A1, class A2> 14void def(char const* name, Fn fn, A1 const&, A2 const&); 15 16template <class Fn, class A1, class A2, class A3> 17void def(char const* name, Fn fn, A1 const&, A2 const&, A3 const&); 18`` 19[variablelist 20[[Requires][name is an [link ntbs] which conforms to Python's [@http://www.python.org/doc/current/ref/identifiers.html identifier naming rules]. 21 22* 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]. 23* 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]. 24 25 [*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. 26 27* 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. 28 29 [table 30 [[Mnemonic Name][Requirements/Type properties][Effects]] 31 [[docstring][Any [link ntbs]][Value will be bound to the `__doc__` attribute of the resulting method overload.]] 32 [[policies][A model of [link concepts.callpolicies CallPolicies]][A copy will be used as the call policies of the resulting method overload.]] 33 [[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.]] 34] 35]] 36] 37[endsect] 38[section Example] 39`` 40#include <boost/python/def.hpp> 41#include <boost/python/module.hpp> 42#include <boost/python/args.hpp> 43 44using namespace boost::python; 45 46char const* foo(int x, int y) { return "foo"; } 47 48BOOST_PYTHON_MODULE(def_test) 49{ 50 def("foo", foo, args("x", "y"), "foo's docstring"); 51} 52`` 53[endsect] 54[endsect] 55