1.7.1 Data conversion when calling COM methods

All IDL definitions map onto FLI definitions, mirroring the mapping that midl.exe does for C/C++. However, IDL provides some additional type information that C/C++ lacks (for instance the string attribute), so there are some additional conversions that Lisp performs when it can.

The COM API uses the information from the IDL to convert data between FLI types and Lisp types where appropriate for arguments and return values of COM method calls. In particular:

• Primitive integer types are represented as Lisp integers.
• Primitive char types are represented as Lisp characters.
• Primitive float types are represented as Lisp float types.
• COM interface pointers are FLI objects represented as objects of type com-interface, which supports type checking of the interface name.
• Except as detailed below, all other COM types are represented as their equivalent FLI types. This includes other pointer types and structs.

In COM, all parameters have a direction which can be either in , out or both in and out (referred to as in-out here). Arguments and values for client-side COM method calls reflect the direction as described in the following sections. For a complete version of the example code, see the file examples\com\manual\args\args-calling.lisp in the LispWorks installation.

1.7.1.1 In parameters

1.7.1.2 Out parameters

1.7.1.3 In-out parameters