theller at python.net
Wed Mar 10 19:17:35 CET 2004
[followup to myself...]
Thomas Heller <theller at python.net> writes:
> I'm currently reinventing the wheel ;-), implementing 'clones' for the
> win32com.client.Dispatch and DispatchWithEvents functions using ctypes.
> It works fairly well, although the more complicated data types like
> SAFEARRAY or RECORD are not yet implemented.
> The win32com.client versions of these functions require makepy support
> (for DispatchWithEvents), and create this on demand. The ctypes
> versions don't require something similar, they are using the ITypeComp
> interface at runtime to bind methods, properties, and constants on
> demand, for events support they use either IProvideClassInfo2 to find
> the outgoing interface, or iterate through the type library to find the
> type info and finally ITypeComp for the default outgoing interface.
> For my own sake, I'm trying to keep the ctypes version as compatible as
> possible to the win32com versions, although I'm not happy by some of the
> design decisions Mark Hammond or whoever wrote this stuff made.
> First, constants defined in the type libraries are exposed in the
> win32com.client.constants instance, which is internally a sequence of
> dictionaries. Wouldn't it be better to have the constants available in
> the object returned by the Dispatch() call itself, maybe in a _constants
> property? I'm also wondering how VB does this...
> My second 'complaint' is about the event handlers. It seems win32com
> prepends 'On' to the method handler names if the method itself, as
> defined in the type library, doesn't already start with 'On'. Take
> Internetexplorer as an example. The DWebBrowserEvents2 outgoing
> interface has methods named "BeforeNavigate2", "NavigateComplete2", and
> "OnQuit". The handlers in Python then must be named
> "OnBeforeNavigate2", "OnNavigateComplete2", and "OnQuit". The method
> names look nice in the Python class implementation, and their templates
> are also available as commented out code in the makepy generated files,
> but looking at the Internet Explorer type library with Oleview, I find
> this very confusing. What is the reason that it was chosen this way?
Maybe this has to do with the fact (I didn't know this before) that
DispatchWithEvents(progid, user_event_class) returns an instance of a
class which has user_event_class as one of its base classes. So, all
the COM methods, properties, and even the event handler methods share a
More information about the Python-list