Python:在扩展模块中引用使用 PyErr_NewException 创建的异常类 [英] Python: Referring to an Exception Class Created with PyErr_NewException in an Extension Module

问题描述

我正在创建自己的 Python 扩展(使用 SWIG，但我希望这无关紧要).

I am creating my own Python extension (using SWIG, but I hope that is not relevant).

在 C++ 方面，我使用 PyErr_NewException 创建自定义异常对象.

In the C++ side of it, I am using PyErr_NewException to create a custom exception object.

// C++ - create a custom Python Exception class.

m = Py_InitModule((char *) "MyModule", SwigMethods);
g_pyMyErr = PyErr_NewException( "MyModule.MyErr", 0, 0 );
Py_INCREF(g_pyMyErr);
int result = PyModule_AddObject(m, "MyErr", g_pyMyErr);

上面的代码返回成功值，我可以成功抛出上面的异常并在Python客户端代码中捕获它.

The above code returns success values and I can throw the above exception successfully and catch it in the Python client code.

问题是这样的:当我在 Python 代码中提到MyErr"时，我收到一条错误消息，指出MyErr"未定义.

The problem is this: When I refer to "MyErr" in Python code I get an error saying "MyErr" is not defined.

// Python client code - catch the exception

from MyModule import *

try:
    causeException()
catch MyErr:  # Error: MyErr is not defined.
    pass
catch Exception:
    pass

我目前的想法是 SWIG 可能正在改变(修改)事物的名称.

My current thinking is that maybe SWIG is altering (mangling) the names of things.

推荐答案

你需要定义错误然后:

%{
  class MyErr {};
%}

另外，我建议添加这个，以便您可以将异常捕获为 MyModule.MyErr 而不是 MyModule._MyModule.MyErr(因为它们将是由 SWIG 生成的):

Also, I would suggest adding this, so that you could catch the exceptions as MyModule.MyErr and not as MyModule._MyModule.MyErr (since that is how they will be generated by SWIG):

%pythoncode %{
  MyErr = _MyModule.MyErr
%}

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