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Chapter 6: Foreign Types 46<br />
foreign-slot-pointer<br />
Syntax<br />
foreign-slot-pointer ptr type slot-name ⇒ pointer<br />
Arguments and Values<br />
[Function]<br />
ptr<br />
type<br />
slot-names<br />
pointer<br />
A pointer to a structure.<br />
A foreign structure type.<br />
A slot name in the type.<br />
A pointer to the slot slot-name.<br />
Description<br />
Returns a pointer to the location of the slot slot-name in a foreign object of type type at<br />
ptr. The returned pointer points inside the structure. Both the pointer and the memory it<br />
points to have the same extent as ptr.<br />
For aggregate slots, this is the same value returned by foreign-slot-value.<br />
Examples<br />
(defcstruct point<br />
"Pointer structure."<br />
(x :int)<br />
(y :int))<br />
<strong>CFFI</strong>> (with-foreign-object (ptr ’(:struct point))<br />
(foreign-slot-pointer ptr ’(:struct point) ’x))<br />
⇒ #<br />
;; Note: the exact pointer representation varies from lisp to lisp.<br />
See Also<br />
[defcstruct], page 33<br />
[foreign-slot-value], page 47<br />
[foreign-slot-names], page 44<br />
[foreign-slot-offset], page 45
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