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with-foreign-pointer

Syntax

— Macro: with-foreign-pointer (var size &optional size-var) &body body

Arguments and Values

var
size-var
A symbol.
size
An integer.
body
A list of forms to be executed.

Description

The with-foreign-pointer macro, binds var to size bytes of foreign memory during body. The pointer in var is invalid beyond the dynamic extend of body and may be stack-allocated if supported by the implementation.

If size-var is supplied, it will be bound to size during body.

Examples

  CFFI> (with-foreign-pointer (string 4 size)
          (setf (mem-ref string :char (1- size)) 0)
          (lisp-string-to-foreign "Popcorns" string size)
          (loop for i from 0 below size
                collect (code-char (mem-ref string :char i))))
  => (#\P #\o #\p #\Null)

See Also

foreign-alloc
foreign-free