如何使python函数作为c ++函数的回调[重复](How to make a python function as callback of a c++ function [duplicate])

如何使python函数作为c ++函数的回调[重复](How to make a python function as callback of a c++ function [duplicate])

可能重复： 使用boost :: python将回调从python传递给c ++

我必须将python函数作为c ++函数的回调。如何做？在哪里可以找到一些例子？ 我想使用boost.python。

Possible Duplicate: pass callback from python to c++ using boost::python

I have to make a python function as callback of a c++ function.How to do?Where can I find some examples?? I want to use boost.python.

最满意答案

我的方法（不是唯一的方法）

在C ++中，我有一个以下列方式提供回调的类：

struct Mesh { template<class Visitor> void visitChildren(Visitor& v) { [...] v.visit([...]) } }

然后当我将类导出到python（仍然是C ++）

struct ChildrenVisitor { ChildrenVisitor(PyObject* self) : self(self) {} void visit( /* .... */ ) { call_method<void>(self, "visit" /*, [...] */ ); } private: PyObject* self; // 1 };

访问者本身导出到python

typedef ChildrenVisitor ClassT; class_<ClassT, boost::noncopyable >("ChildrenVisitor", init<PyObject*>() );

而对于Mesh的出口，你做的

.def("visitChildren", &Mesh::template visitChildren<ChildrenVisitor> )

我总是用...你可以在哪里插入任何参数。

在python中你做这样的事情

class MyVisitor(ChildrenVisitor): def __init__(self): ChildrenVisitor.__init__(self,self) def visit(self): # do whatever you want

我还想创建一个接受lambda函数的ChildrenVisitor的子类，这使得访问者可以用python单行编写。

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哦，顺便问一下。 如果你想稍后调用该函数，那么你需要将C ++实现改为这样的

struct ChildrenVisitorBase { virtual void visit( /* .... */ ) = 0; }; struct Mesh { void registerCallback(shared_ptr<ChildrenVisitorBase> v) { visitors.push_back(v) } void doSomeWork() { // ... for(int i=0; i < visitors.size(); ++i) visitors[i]->visit( /* ... */ ) } std::vector< shared_ptr<ChildrenVisitorBase> > visitors; }

并使ChildrenVisitor实现ChildrenVisitorBase 。

My approach to this (not the only way)

In C++ I have a class that provides a callback in the following way:

struct Mesh { template<class Visitor> void visitChildren(Visitor& v) { [...] v.visit([...]) } }

and then when I export the class to python (still C++)

struct ChildrenVisitor { ChildrenVisitor(PyObject* self) : self(self) {} void visit( /* .... */ ) { call_method<void>(self, "visit" /*, [...] */ ); } private: PyObject* self; // 1 };

The export of the visitor itself to python

typedef ChildrenVisitor ClassT; class_<ClassT, boost::noncopyable >("ChildrenVisitor", init<PyObject*>() );

And for the export of Mesh you do

.def("visitChildren", &Mesh::template visitChildren<ChildrenVisitor> )

I always used ... where you can insert any of your arguments.

In python you do something like this

class MyVisitor(ChildrenVisitor): def __init__(self): ChildrenVisitor.__init__(self,self) def visit(self): # do whatever you want

I also like to make a subclass of ChildrenVisitor that accepts lambda functions, that makes writing visitors in python single lines.

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Oh, btw. if you want to call the function at some later point then you would need to change the C++ implementation to something like this

struct ChildrenVisitorBase { virtual void visit( /* .... */ ) = 0; }; struct Mesh { void registerCallback(shared_ptr<ChildrenVisitorBase> v) { visitors.push_back(v) } void doSomeWork() { // ... for(int i=0; i < visitors.size(); ++i) visitors[i]->visit( /* ... */ ) } std::vector< shared_ptr<ChildrenVisitorBase> > visitors; }

And make ChildrenVisitor implement ChildrenVisitorBase.