set-variant

set-variant Function

Summary

Sets the fields in a VARIANT pointer.

Package

com

Signature

set-variant variant type &optional value

Arguments

`variant`⇩	A foreign pointer to an object of type `VARIANT`.
`type`⇩	A keyword specifying the type of value.
`value`⇩	The value to store in `variant`.

Description

The function set-variant can be used to set the type and value of a VARIANT object. It is useful if the default type provided by the automatic conversion for VARIANT return values is incorrect. The value of meaning of type is an specified below.


Value of `type`	`VT` code used	Expected type of `value`
`nil`	dynamic	any suitable
`:empty`	`VT_EMPTY`	ignored
`:null`	`VT_NULL`	ignored
`:short`	`VT_I2`	integer
`:long`	`VT_I4`	integer
`:float`	`VT_R4`	single-float
`:double`	`VT_R8`	double-float
`:cy`	`VT_CY`
`:date`	`VT_DATE`
`:bstr`	`VT_BSTR`	string
`:dispatch`	`VT_DISPATCH`	FLI pointer
`:error`	`VT_ERROR`	ignored
`:bool`	`VT_BOOL`	`nil` or non `nil`
`:variant`	`VT_VARIANT`	FLI pointer
`:unknown`	`VT_UNKNOWN`	FLI pointer
`:decimal`	`VT_DECIMAL`
`(:unsigned :char)`	`VT_UI1`	integer
`(:array . type)`	`VT_BYREF +` `VT` code for `type`	array
`:array` or `(:array array)` or `(:array . types)`	`VT_ARRAY + VT_VARIANT`	array
`(:pointer type2)`	`VT_BYREF +` `VT` code for `type2`	FLI pointer

If type is nil then the actual VT code is chosen dynamically according to the Lisp type of value (see Automation types, VT codes and their corresponding Lisp types).

If type is a cons of the form (:array . type) for some keyword type, then variant is set to contain an array of objects of type. Each element of value is expected to be suitable for conversion to type.

If type is :array or another list starting with :array then variant is set to contain an array of VARIANT objects with the same dimensions as value. Each element of value is converted as if by calling set-variant with a type chosen as follows:

If type is the symbol :array, then nil is passed as the element type.
If type is of the form (:array array) then array should be an array with the same dimensions as value. The element type is taken from the corresponding element of array.
If type is of the form (:array . types) then types should be a suitable value for the :initial-contents argument to make-array to make an array of types with the same dimensions as value. The element type is taken from the corresponding element of that array. In particular, if value is a vector of length n then type should be a list of the form (:array type-1 type-2 ... type-n).

Examples

(set-variant v :null)

(set-variant v :short 10)

(set-variant v '(:pointer :short) ptr)

(set-variant v '(:array :short :int) #(1 2))