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Asked: 2026-05-26T09:14:53+00:00

I’ve been working on a problem for over a week, so I may be

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I’ve been working on a problem for over a week, so I may be blind, frustrated or just plain nuts. Please forgive me, but….

My class has this member:

IDevicePtr  devicePtr

a function wants (IDevicePtr * ptr) as a parameter.

I can’t pass devicePtr to it, natural reasons:

cannot convert parameter 2 from 'IDevicePtr' to 'IDevicePtr *

BUT…

i also can’t pass &devicePtr to it:

compiler screams: cannot convert parameter 2 from 'IDevice **' to 'IDevicePtr *'

Where did “Idevice**” come from? How can I satisfy the “IDevicePtr *” function parameter requirements when I have an IDevicePtr object?

Sorry for the frustration. I’ve spent the last week trying to intercept one COM event without using ATL or MFC. No success. I haven’t been able to locate a living person who ever did something like that.

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1 Answer

  1. Editorial Team

    _COM_SMARTPTR_TYPEDEF defines a pointer wrapper class – you can think of it as basically typedef IDevice *IDevicePtr, except that your IDevicePtr auto-releases and auto-references.

    You should not be passing IDevicePtr *s around. Pass around IDevice * and wrap it in a IDevicePtr only if you take a reference, or pass a IDevice ** if you want to return-by-reference (you can take the address of an IDevicePtr to get an IDevice **). Do not attempt to use a IDevicePtr * for return-by-reference; this will fail (this is the problem you are seeing) because of that operator& overload.

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