Question

我正在使用PyObjC。 PyObjC没有提供method_exchangeImplementations的接口，所以我试图通过ctypes使用该函数。我试图从某个窗口控制器类中覆盖windowShouldClose:。

我的代码：

import objc
BrowserWindowController = objc.lookUpClass("BrowserWindowController")

class BrowserWindowController(objc.Category(BrowserWindowController)):
    def myWindowShouldClose_(self, sender):
        print "myWindowShouldClose", self, sender
        return self.myWindowShouldClose_(sender)

from ctypes import *
capi = pythonapi

# id objc_getClass(const char *name)
capi.objc_getClass.restype = c_void_p
capi.objc_getClass.argtypes = [c_char_p]

# SEL sel_registerName(const char *str)
capi.sel_registerName.restype = c_void_p
capi.sel_registerName.argtypes = [c_char_p]

def capi_get_selector(name):
    return c_void_p(capi.sel_registerName(name))

# Method class_getInstanceMethod(Class aClass, SEL aSelector)
# Will also search superclass for implementations.
capi.class_getInstanceMethod.restype = c_void_p
capi.class_getInstanceMethod.argtypes = [c_void_p, c_void_p]

# void method_exchangeImplementations(Method m1, Method m2)
capi.method_exchangeImplementations.restype = None
capi.method_exchangeImplementations.argtypes = [c_void_p, c_void_p]

def hook_into_close():
    clazz = capi.objc_getClass("BrowserWindowController")
    origClose = capi.class_getInstanceMethod(clazz, capi_get_selector("windowShouldClose:"))
    newClose = capi.class_getInstanceMethod(clazz, capi_get_selector("myWindowShouldClose:"))
    capi.method_exchangeImplementations(origClose, newClose)

这次崩溃。在[NSWindow _close]中有一些奇怪的回溯。

代码基本上是对的吗？

有什么问题？

Answer 1

啊，当我在@objc.signature(BrowserWindowController.windowWillClose_.signature)前面添加def myWindowShouldClose_时，它不再崩溃。

所以它只是错误/不匹配的签名。

PyObjC和method_exchangeImplementations：崩溃。正确用法？

1 个答案: