Thread overview
How to COM interfaces work
Mar 19
evilrat
Mar 19
evilrat
March 19
I have a COM interface that is dynamically created using invoke and such.

One of the functions returns an interface. It is just a value of IUnknown or whatever.

If I use it as a pointer in to the the D interface equivalent, it crashes as the value is not pointing to anything valid.

What do these values represent? I tried to use QueryInterface from the class who's function provides the "COM interface" but it returns interface not supported.

So, I have one dynamic COM interface that I initialize properly and can call it's functions and all the ones I tested work fine. Some of those functions returns interfaces. If I try to call the functions on those interfaces, the app crashes.

How to I get the interfaces the return values represent? Or for that matter, the functions that ask for an interface, what do I pass? Passing or using the generated D interfaces does not work.


March 19
On Sunday, 19 March 2017 at 02:04:53 UTC, StarGrazer wrote:
> I have a COM interface that is dynamically created using invoke and such.
>
> One of the functions returns an interface. It is just a value of IUnknown or whatever.
>
> If I use it as a pointer in to the the D interface equivalent, it crashes as the value is not pointing to anything valid.
>
> What do these values represent? I tried to use QueryInterface from the class who's function provides the "COM interface" but it returns interface not supported.
>
> So, I have one dynamic COM interface that I initialize properly and can call it's functions and all the ones I tested work fine. Some of those functions returns interfaces. If I try to call the functions on those interfaces, the app crashes.
>
> How to I get the interfaces the return values represent? Or for that matter, the functions that ask for an interface, what do I pass? Passing or using the generated D interfaces does not work.

I'm sorry, but probably you should read something like this[1] first, this tech(COM) is beyond D, so you must understand how it works before trying it in D.

[1] https://www.codeproject.com/Articles/633/Introduction-to-COM-What-It-Is-and-How-to-Use-It
March 19
On Sunday, 19 March 2017 at 02:45:48 UTC, evilrat wrote:
> On Sunday, 19 March 2017 at 02:04:53 UTC, StarGrazer wrote:
>> I have a COM interface that is dynamically created using invoke and such.
>>
>> One of the functions returns an interface. It is just a value of IUnknown or whatever.
>>
>> If I use it as a pointer in to the the D interface equivalent, it crashes as the value is not pointing to anything valid.
>>
>> What do these values represent? I tried to use QueryInterface from the class who's function provides the "COM interface" but it returns interface not supported.
>>
>> So, I have one dynamic COM interface that I initialize properly and can call it's functions and all the ones I tested work fine. Some of those functions returns interfaces. If I try to call the functions on those interfaces, the app crashes.
>>
>> How to I get the interfaces the return values represent? Or for that matter, the functions that ask for an interface, what do I pass? Passing or using the generated D interfaces does not work.
>
> I'm sorry, but probably you should read something like this[1] first, this tech(COM) is beyond D, so you must understand how it works before trying it in D.
>
> [1] https://www.codeproject.com/Articles/633/Introduction-to-COM-What-It-Is-and-How-to-Use-It

Please don't be condescending to me. You have no idea how much I know or don't know. I already have most of the COM stuff working in D so I do know something. I'm not a complete idiot like you are presupposing. I am asking a very simple question and if you don't know the answer then may you should read the article to know if I know enough or not.


March 19
On Sunday, 19 March 2017 at 02:04:53 UTC, StarGrazer wrote:
> If I use it as a pointer in to the the D interface equivalent, it crashes as the value is not pointing to anything valid.

What's the code look like? What interface too?
March 19
On Sunday, 19 March 2017 at 02:45:48 UTC, evilrat wrote:
> On Sunday, 19 March 2017 at 02:04:53 UTC, StarGrazer wrote:
>> I have a COM interface that is dynamically created using invoke and such.
>>
>> One of the functions returns an interface. It is just a value of IUnknown or whatever.
>>
>> If I use it as a pointer in to the the D interface equivalent, it crashes as the value is not pointing to anything valid.
>>
>> What do these values represent? I tried to use QueryInterface from the class who's function provides the "COM interface" but it returns interface not supported.
>>
>> So, I have one dynamic COM interface that I initialize properly and can call it's functions and all the ones I tested work fine. Some of those functions returns interfaces. If I try to call the functions on those interfaces, the app crashes.
>>
>> How to I get the interfaces the return values represent? Or for that matter, the functions that ask for an interface, what do I pass? Passing or using the generated D interfaces does not work.
>
> I'm sorry, but probably you should read something like this[1] first, this tech(COM) is beyond D, so you must understand how it works before trying it in D.
>
> [1] https://www.codeproject.com/Articles/633/Introduction-to-COM-What-It-Is-and-How-to-Use-It

Reading that tells me nothing about how to get a dynamic COM interface of a dynamic COM interface... but I guess you knew that, didn't you? I'm sorry, but you are an ____.



March 19
On Sunday, 19 March 2017 at 03:10:02 UTC, Adam D. Ruppe wrote:
> On Sunday, 19 March 2017 at 02:04:53 UTC, StarGrazer wrote:
>> If I use it as a pointer in to the the D interface equivalent, it crashes as the value is not pointing to anything valid.
>
> What's the code look like? What interface too?

It's very complicated. I use a lot of reflection to extract the interface functions and build a d class from them.

Like I said, the initial dynamic COM interface works fine. I can call it's functions so all that code is irrelevant.

The problem is, some of those functions return COM interfaces(they inherit IDispatch interfaces in D).

The interfaces are generated from idl2d. So they are just standard d interfaces that only mock up the COM interfaces.

But it is probably not a D issue.

IDispatch.Invoke returns a COM VARIANT type with the return type(which is an IDispatch interface according to idl2d).



HRESULT CoCreateInstance(
  _In_  REFCLSID  rclsid,
  _In_  LPUNKNOWN pUnkOuter,
  _In_  DWORD     dwClsContext,
  _In_  REFIID    riid,
  _Out_ LPVOID    *ppv
);


https://msdn.microsoft.com/en-us/library/windows/desktop/ms686615(v=vs.85).aspx

I assume I'll have to use that to create the COM of COM by passing the returned value from invoke in to the pUnkOuter and do all that. I haven't tried it yet but will when I get a chance.


I'd just like to get some conformation on the process so at least I know I'm headed in the right direction. The project is pretty complex and most of the stuff is done in compile time code.

March 19
On Sunday, 19 March 2017 at 03:27:28 UTC, StarGrazer wrote:
>
>
> I'd just like to get some conformation on the process so at least I know I'm headed in the right direction. The project is pretty complex and most of the stuff is done in compile time code.

What debug shows? If CoCreateInstance and calling other interfaces is working for you, then it could be really D issue, because not much people really use this stuff. Also it could be wrong vptr table (method order issue) generated from reflection, or it could be D vptr issues related to com (can you try interface instead of class?), or D compiler bugs or wrong ABI(try different compilers/versions)

That's probably it, not sure if there is other potential quirks out there...