[1/2] qcap: Distinguish interface and implementation pointer for VfwCapture output pin.

Sebastian Lackner sebastian at fds-team.de
Mon Jun 29 06:11:51 CDT 2015

On 29.06.2015 12:50, Nikolay Sivov wrote:
> On 29.06.2015 13:13, Sebastian Lackner wrote:
>> Thanks for the feedback. In this case pOutputPin is basically part of the same object,
>> not an arbitrary external interface. It is constructed with VfwPin_Construct ->
>> BaseOutputPin_Construct, and also holds a reference to the critical section of the parent
>> object for example, so there is no clear distinction between public/private interfaces
>> anyway.
>> Most other code parts which use BaseOutputPin_Construct store the result in something like:
>> (IPin **)&This->store_impl_pointer_here where the variable already has the corresponding
>> implementation type. Should we change it here too? Using only the public interface is not possible,
>> take a look at for example the following code part, where a private member is set from a
>> different interface:
>> --- snip ---
>>          This->driver_info = qcap_driver_init( This->pOutputPin,
>>                 var.__VARIANT_NAME_1.__VARIANT_NAME_2.__VARIANT_NAME_3.ulVal );
>>          if (This->driver_info)
>>          {
>>              pin = impl_from_IPin(This->pOutputPin);
>>              pin->driver_info = This->driver_info; // <---
>> --- snip ---
> I personally prefer to use public interface, usually it makes things more clear, and code doesn't depend on implementation changes.
> If in this particular case it's not possible then yes, we should store impl pointer instead of interface pointer.

Okay, I'll resend an updated version later then.

> By the way, variant thing looks a little insane, assuming intention was to get V_UI4(&var), which is not necessary right on its own as qcap_driver_init() takes USHORT argument.

Yes, I also noticed it. Changes to this part should probably be in a separate patch though.

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