将附加参数传递给 python 回调对象 (win32com.client.dispatchWithEvents)

Question

我正在使用 win32com 包与 windows 应用程序交互（应用程序并不重要）。

简而言之，我想要实现的是订阅更新的表。

我已经成功实现了一个回调，它在更新表时接收返回的数据，但我现在需要对收到的数据采取行动。

如果我可以使用附加参数实例化回调对象，这个问题将很容易解决（见下面的代码）但我不知道如何做到这一点。

---

回调类：

class callBackEvents(object):
    """ Callback Object for win32com
    """

    def OnNewData(self, XMLData):
        logging.info("Subscription returned information")
        print "HERE : {}".format(XMLData))
        
        # Would like to use some argument to access logic
        # For how to use the new data  

    def OnActionResult(self, job, msg):
        return True

    def OnServerDisconnect(self):
        logging.debug("Server Disconnected")

    def OnServerConnect(self):
        logging.debug("Trader Connected To Server")

---

实例化回调对象：

# Instantiate API com object
self.app = win32com.client.DispatchWithEvents("WindowsApplication" callBackEvents)
# I would like to give the callback object extra arguments e.g. callBackEvents(params)

---

编辑 实例化回调对象：

# Instatiate two com objects
self.com1 = win32com.client.DispatchWithEvents("WindowsApplication" callBackEvents)
self.com2 = win32com.client.DispatchWithEvents("WindowsApplication" callBackEvents)

# Create multiple subscriptions (Note these are asynchronous)
# Pushing the subscribed info is not a problem and done elsewhere
self.com1.Subscribe(<subscription info>)
self.com2.Subscribe(<subscription info>)

现在，当订阅信息遇到回调对象时，我不知道是哪个 com 对象设置了订阅（我可以根据返回的信息猜测，但是在设置相同的订阅时这会导致问题）

Answer 1

我遇到了同样的问题，最终增加了 DispatchWithEvents。请看下面我的解决方案（我认为它更优雅）：

from win32com.client import Dispatch
from win32com.client import gencache
from win32com.client import getevents
from win32com.client import EventsProxy
import pythoncom

def _event_setattr_(self, attr, val):
    try:
        # Does the COM object have an attribute of this name?
        self.__class__.__bases__[0].__setattr__(self, attr, val)
    except AttributeError:
        # Otherwise just stash it away in the instance.
        self.__dict__[attr] = val

def DispatchWithEvents(clsid, user_event_class, arguments):
    # Create/Get the object.
    disp = Dispatch(clsid)
    if not disp.__class__.__dict__.get("CLSID"): # Eeek - no makepy support - try and build it.
        try:
            ti = disp._oleobj_.GetTypeInfo()
            disp_clsid = ti.GetTypeAttr()[0]
            tlb, index = ti.GetContainingTypeLib()
            tla = tlb.GetLibAttr()
            gencache.EnsureModule(tla[0], tla[1], tla[3], tla[4], bValidateFile=0)
            # Get the class from the module.
            disp_class = gencache.GetClassForProgID(str(disp_clsid))
        except pythoncom.com_error:
            raise TypeError("This COM object can not automate the makepy process - please run makepy manually for this object")
    else:
        disp_class = disp.__class__
    # If the clsid was an object, get the clsid
    clsid = disp_class.CLSID
    # Create a new class that derives from 3 classes - the dispatch class, the event sink class and the user class.
    # XXX - we are still "classic style" classes in py2x, so we need can't yet
    # use 'type()' everywhere - revisit soon, as py2x will move to new-style too...
    try:
        from types import ClassType as new_type
    except ImportError:
        new_type = type # py3k
    events_class = getevents(clsid)
    if events_class is None:
        raise ValueError("This COM object does not support events.")
    result_class = new_type("COMEventClass", (disp_class, events_class, user_event_class), {"__setattr__" : _event_setattr_})
    instance = result_class(disp._oleobj_) # This only calls the first base class __init__.
    events_class.__init__(instance, instance)
    args = [instance] + arguments
    if hasattr(user_event_class, "__init__"):
        user_event_class.__init__(*args)
    return EventsProxy(instance)

您的处理程序类必须有一个__init__ 函数并准备好按顺序接受参数：

class Handler_Class():
            def __init__(self, cls):
                self.cls = cls
            def OnItemAdd(self, mail):
                #Check if the item is of the MailItem type
                if mail.Class==43:
                    print("##########",inbox, "##########")
                    print(mail.Subject, " - ", mail.Parent.FolderPath)
                    label = cls.label_email(datetime.now(),mail)
                    print("=======>",label)

你可以这样初始化它：

clsGED = classifier.PersonClassifier()
items = win32com.client.DispatchEx("Outlook.Application").GetNamespace("MAPI").Folders[<emailaddress>].Folders["Inbox"].Items
utilities.DispatchWithEvents(items, Handler_Class, [cls])

正如您可能已经猜到的那样，这里的应用程序用于数据科学项目，其中传入的电子邮件被自动分类，但新的 DispatchWithEvents 方法非常通用，并且接受动态数量的参数。

Answer 2

由于您可能只有一个应用实例，因此只有一个 DispatchWithEvents，您可以简单地将参数设置为该类的成员：

class callBackEvents(object):
    """ Callback Object for win32com
    """

    params = None

    def OnNewData(...

    ...

# populate the params field
callBackEvents.params = yourParams

self.app = win32com.client.DispatchWithEvents("WindowsApplication", callBackEvents)

您当然可以将 params 设为全局变量，但您应该仅将全局变量用作最后的手段或用于常量。