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Sean
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 Posted: Fri Jan 16, 2004 8:18 pm Post subject: Return an IUnknown from automation object |
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Hi,
I'm would like to create a method in my automation object that has an
[out] parameter of type IUnknown *. When I attempt to update the TLB,
it gives the error 'Out parameter requires pointer type'. I thought
the * indicated a pointer type but apparently not. Is there a way to
return an IUnknown?
thanks,
Sean
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John Carlyle-Clarke
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| Posted: Mon Jan 19, 2004 9:10 am Post subject: Re: Return an IUnknown from automation object |
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[email]delphiconsultingguy (AT) yahoo (DOT) com[/email] (Sean) wrote in
news:c9b4f122.0401161218.d64bc0b (AT) posting (DOT) google.com:
| Quote: | Hi,
I'm would like to create a method in my automation object that has
an [out] parameter of type IUnknown *. When I attempt to update
the TLB, it gives the error 'Out parameter requires pointer type'.
I thought the * indicated a pointer type but apparently not. Is
there a way to return an IUnknown?
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Yes, there is. This is a bit misleading really. The simple answer is
this : use IUnknown**
IIRC, this only occurs if you use IDL rather than Pascal style for the
TLB editor. In Delphi, IUnknown is an interface, but in C (which IDL
derives from) you only ever deal with interface pointers. Therefore,
IUnknown* in IDL is equivalent to IUnknown in Pascal. Therefore, if
you want an interface {reference|pointer} that you can modify (for an
out param) you need IUnknown**.
Just think of IUnknown* or IDispatch* or IWhatever* as interfaces
(since interfaces are only ever pointers, really), and then it makes
sense.
HTH.
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Sean
Guest
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| Posted: Tue Jan 20, 2004 7:14 pm Post subject: Re: Return an IUnknown from automation object |
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| Quote: | Yes, there is. This is a bit misleading really. The simple answer is
this : use IUnknown**
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The answer is as suprisingly obvious as it is unlikely. Many thanks,
Sean
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