boost python def 函數匯出

Introduction

def() is the function which can be used to expose C++ functions and callable objects as Python functions in the current scope.

這個函數可以協助我們將C++中的函數匯出到Python中，供Python使用。說實話，真的很好用。

Functions

def

template <class F>void def(char const* name, F f);template <class Fn, class A1>void def(char const* name, Fn fn, A1 const&);template <class Fn, class A1, class A2>void def(char const* name, Fn fn, A1 const&, A2 const&);template <class Fn, class A1, class A2, class A3>void def(char const* name, Fn fn, A1 const&, A2 const&, A3 const&);

Requires: name is an ntbs which conforms to Python's identifier
naming rules.

• If Fn is [derived from] object, it will be added to the
  current scope as a single overload. To be useful, fn should be callable.
• If a1 is the result of an overload-dispatch-expression, only the second form
  is allowed and fn must be a pointer to function or pointer to member function whose arity is the same as A1's maximum
  arity.

  Effects: For each prefix  P of  Fn's sequence of argument types, beginning with the one whose length is  A1's  minimum
  arity, adds a  name(... ) function overload to the 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.

• 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.

Memnonic Name	Requirements/Type properties	Effects
docstring	Any ntbs.	Value will be bound to the __doc__ attribute of the resulting method overload.
policies	A model of CallPolicies	A copy will be used as the call policies of the resulting method overload.
keywords	The result of a keyword-expression specifying no more arguments than thearity of fn.	A copy will be used as the call policies of the resulting method overload.

Example例子，其實按照下面的例子，很容易就明白了。主要是

第一個參數，填寫你在Python中使用他的名字第二個參數，寫上函數指標第三個參數，填上參數名，好讓boost只要你的函數有幾個參數。第四個參數，是描述，可以忽略其實還有個很重要的是返回協議（return policy )，詳見：http://blog.csdn.net/cedricporter/article/details/6828322

#include <boost/python/def.hpp>#include <boost/python/module.hpp>#include <boost/python/args.hpp>using namespace boost::python;char const* foo(int x, int y) { return "foo"; }BOOST_PYTHON_MODULE(def_test){    def("foo", foo, args("x", "y"), "foo's docstring");}

7 March, 2003

Copyright Dave Abrahams 2002.