def getevents(clsid):
"""Determine the default outgoing interface for a class, given
either a clsid or progid. It returns a class - you can
conveniently derive your own handler from this class and implement
the appropriate methods.
This method relies on the classes produced by makepy. You must use
either makepy or the gencache module to ensure that the
appropriate support classes have been generated for the com server
that you will be handling events from.
Beware of COM circular references. When the Events class is connected
to the COM object, the COM object itself keeps a reference to the Python
events class. Thus, neither the Events instance or the COM object will
ever die by themselves. The 'close' method on the events instance
must be called to break this chain and allow standard Python collection
rules to manage object lifetimes. Note that DispatchWithEvents() does
work around this problem by the use of a proxy object, but if you use
the getevents() function yourself, you must make your own arrangements
to manage this circular reference issue.
Beware of creating Python circular references: this will happen if your
handler has a reference to an object that has a reference back to
the event source. Call the 'close' method to break the chain.
Example:
>>>win32com.client.gencache.EnsureModule('{EAB22AC0-30C1-11CF-A7EB-0000C05BAE0B}',0,1,1)
<module 'win32com.gen_py.....
>>>
>>> class InternetExplorerEvents(win32com.client.getevents("InternetExplorer.Application.1")):
... def OnVisible(self, Visible):
... print "Visibility changed: ", Visible
...
>>>
>>> ie=win32com.client.Dispatch("InternetExplorer.Application.1")
>>> events=InternetExplorerEvents(ie)
>>> ie.Visible=1
Visibility changed: 1
>>>
"""
# find clsid given progid or clsid
clsid = str(pywintypes.IID(clsid))
# return default outgoing interface for that class
klass = gencache.GetClassForCLSID(clsid)
try:
return klass.default_source
except AttributeError:
# See if we have a coclass for the interfaces.
try:
return gencache.GetClassForCLSID(
klass.coclass_clsid).default_source
except AttributeError:
return None
def __WrapDispatch(dispatch, userName = None, resultCLSID = None, typeinfo = None, \
UnicodeToString = NeedUnicodeConversions, clsctx = pythoncom.CLSCTX_SERVER,
WrapperClass = None):
"""
Helper function to return a makepy generated class for a CLSID if it exists,
otherwise cope by using CDispatch.
"""
if resultCLSID is None:
try:
typeinfo = dispatch.GetTypeInfo()
if typeinfo is not None: # Some objects return NULL, some raise exceptions...
resultCLSID = str(typeinfo.GetTypeAttr()[0])
except (pythoncom.com_error, AttributeError):
pass
if resultCLSID is not None:
import gencache
# Attempt to load generated module support
# This may load the module, and make it available
klass = gencache.GetClassForCLSID(resultCLSID)
if klass is not None:
return klass(dispatch)
# Return a "dynamic" object - best we can do!
if WrapperClass is None: WrapperClass = CDispatch
return dynamic.Dispatch(dispatch,
userName,
WrapperClass,
typeinfo,
UnicodeToString=UnicodeToString,
clsctx=clsctx)