uffi/doc ref.sgml,1.33,1.34

Update of /pubcvs/uffi/doc
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	ref.sgml 
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Index: ref.sgml
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RCS file: /pubcvs/uffi/doc/ref.sgml,v
retrieving revision 1.33
retrieving revision 1.34
diff -C2 -d -r1.33 -r1.34
*** ref.sgml	23 Nov 2002 18:03:30 -0000	1.33
--- ref.sgml	5 May 2003 21:57:50 -0000	1.34
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*** 1544,1547 ****
--- 1544,1566 ----
  </programlisting>
  
+ <para>  Foreign functions that return pointers to freshly allocated
+ strings should in general not return cstrings, but foreign strings.
+ (There is no portable way to release such cstrings from Lisp.)  The
+ following is an example of handling such a function.  </para>
+ 
+ <programlisting>
+ (uffi:def-function ("readline" c-readline)
+     ((prompt :cstring))
+   :returning (* :char))
+ 
+ (defun readline (prompt)
+   "Reads a string from console with line-editing."
+   (with-cstring (c-prompt prompt)
+       (let* ((c-str (c-readline c-prompt))
+              (str (convert-from-foreign-string c-str)))
+         (uffi:free-foreign-object c-str)
+         str)))
+ </programlisting>
+ 
  </partintro>