Macro

Summary

Accesses a place containing an interface pointer, maintaining reference counts.

Package

com

Signature

interface-ref iptr => iptr

(setf interface-ref) new-value iptr => new-value

Arguments

iptr

A place containing a COM interface pointer or nil.

new-value

A COM interface pointer or nil.

Description

interface-ref is useful when manipulating a place containing an interface pointer.

The setf expander increments the reference count, as if by add-ref, of new-value, unless it is nil. It then decrements the reference count, as if by release, of the existing value in iptr, unless this is nil. Note that this order is important in the case that the new value is the same as the current value. Finally the value of place iptr is set to new-value.

The reader interface-ref simply returns its argument and does no reference counting. It may be useful in a form which both reads and writes a place like incf.

See also

add-ref
release