1.8.6.3 Out parameters

For out parameters:

• A parameter whose type is an array type or a pointer type with a size_is attribute will be converted to a Lisp array of the appropriate size allocated for the dynamic extent of the body forms. After the body has been evaluated, the contents of the array will be copied into the foreign array that the caller has supplied.
• For other types, the parameter will be nil initially and the body should use setq to set it to the value to be returned.

In the latter case, the value will be converted to a foreign object after the body has been evaluated. The following conversions are done:

• For a parameter with the string attribute, a Lisp string will be converted to a foreign string using CoTaskMemAlloc() .
• For a parameter of COM type BSTR* , a Lisp string will be converted to a foreign string using SysAllocString() .
• For a parameter of COM type VARIANT* , the value can be any Lisp value, with the VT code being set according to the Lisp type (see Automation types, VT codes and their corresponding Lisp types). If exact control is required, use the pass-style :foreign and the function set-variant.
• For a parameter of COM type SAFEARRAY( type )* , the value can be either a foreign pointer to an appropriate SAFEARRAY or a Lisp array. In the latter case, a new SAFEARRAY is created which contains the elements of the Lisp array converted as in Automation types, VT codes and their corresponding Lisp types.
• For a parameter of COM type VARIANT_BOOL* , the value can be a generalized boolean.
• Otherwise, the Lisp value will be converted using the FLI according to the mapping of types defined in FLI types.