Am 19.12.2013 14:04, schrieb Wedel, Jan: > Hi Thomas, > > Yesterday, in the evening, I actually found a solution (at least I > believe it). I’ve written some more precise description on StackOverflow: > http://stackoverflow.com/questions/20546303/ctypes-memory-management-when-returning-pointers-in-com-server > > But the summary is: > > I had to explicitly allocate memory with windll.ole32.CoTaskMemAlloc for > anything that is returned by pointer like strings, pointers to structs, > pointer to arrays of structs. > > I saw some C++ implementation that called that function for a pointer to > an array so I was wandering if com types is doing it. So I found out > that it’s actually not. > > In one of your test cases, I saw one function that creates a COM string > with this function so I used that as a base for the other allocations I > needed (structs, arrays). See StackOverflow for the code. > > I thought that com types is actually handling that for me by allocating > memory for everything that is returned.
comtypes uses only two automation compatible types that are probably allocated by CoTaskMemAlloc internally: BSTR and SAFEARRAY. But both of these types are created by wrapper functions from the windows api, SysAllocString and SafeArrayCreate which (I assume) use CoTaskMemAlloc internally. > The most interesting thing is that the code worked on XP without > allocation. But on the MSDN forum, they told me that they’d changed that > memory manager in Windows 7 /Server 2003. I found another post on stackoverflow, where in the second answer someone writes: """This causes undiagnosable memory leaks on Windows XP, a hard exception on Vista and up.""" http://stackoverflow.com/questions/10055607/when-using-cotaskmemalloc-should-i-always-call-cotaskmemfree > Do you think the approach is correct or do see any obvious problems with > that? Yes it looks correct to me. Thomas ------------------------------------------------------------------------------ Rapidly troubleshoot problems before they affect your business. Most IT organizations don't have a clear picture of how application performance affects their revenue. With AppDynamics, you get 100% visibility into your Java,.NET, & PHP application. Start your 15-day FREE TRIAL of AppDynamics Pro! http://pubads.g.doubleclick.net/gampad/clk?id=84349831&iu=/4140/ostg.clktrk _______________________________________________ comtypes-users mailing list comtypes-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/comtypes-users
