python Ctype：回调在python自定义库中的问题 [英] python Ctype : problem with callback in making python custom library

问题描述

整个场景是这样的：

• 在我的c库中有一个函数setmessagelistener（a_structure，function_pointer） >
  

• 我在写一个 python库，这是一个包装器上面提到的c库使用 Ctypes 。
  所以我做的是这样的：

• there is a function setmessagelistener(a_structure,function_pointer) in my c library.

• i am writing a python library which is a wrapper on above mentioned c library using Ctypes. so what i did is something like this:

def setlistener(a_structure,function_pointer)

 listenerDeclaration = CFUNCTYPE(c_void_p, c_void_p)

 listenerFunction = listenerDeclaration(function_pointer)

 setMsgListener = c_lib.setMessageListener

 setMsgListener.argtypes = [c_void_p, c_void_p]

 setMsgListener.restype = c_ubyte

 if (setMsgListener(a_structure, listenerFunction)==0):

    sys.exit("Error setting message listener.")

现在，另一个python程序使用上面的函数从我的python库做工作，但问题是：

当我运行程序它给我分段错误，因为本地对象已经垃圾收集（我认为这样）当控制从库函数setListener（）返回时，它是一个局部对象。

when i run the program it gives me segmentation fault because the local object( listenerfunction) is already garbage collected(i think so) when control returned from the library function setListener() as it being a local object.

有没有解决方案/解决方案？或者我失去了什么？
请提前...
beforex

is there any workaround/solution to this problem?or am i missing something? please suggest... thanx in advance

推荐答案

引用listenerFunction，只要它需要。

As you suspect, you need to keep a reference to listenerFunction as long as it is needed. Perhaps wrap the function in a class, create an instance and set the listenerFunction as a member variable.

请参阅Python文档ctypes

See the Python documentation for ctypes callbacks, especially the important note at the end of the section.

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