FAQ 34.32 What limitations are there on dual interfaces?

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The primary limitation of dual interfaces is that arguments and return types are restricted to the Automation-compatible data types:

  • boolean

  • unsigned char

  • short, int, long

  • float, double

  • currency, Date

  • text strings

  • status codes

  • pointers to COM interfaces

  • pointers to dispatch interfaces

  • arrays of these types

  • references to these types

These data types are defined by COM; they are not C++ data types, although there is a mapping from these data types to C++ data types. The reason that dual interfaces are restricted to these data types is that these are the data types that can be passed to IDispatch::Invoke, and every custom method of a dual interface has a corresponding automation method that is invoked using IDispatch::Invoke.



C++ FAQs
C Programming FAQs: Frequently Asked Questions
ISBN: 0201845199
EAN: 2147483647
Year: 2005
Pages: 566
Authors: Steve Summit

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