Fix Python examples to compile and run under Python 3

Examples/python/index.html

@@ -89,21 +89,10 @@ to look at the <a href="http://www.python.org/sigs/distutils-sig/">distutils</a>
 
 <h2>Compatibility</h2>
 
-The examples have been extensively tested on the following platforms:
-
-<ul>
-<li>Linux
-<li>Solaris
-</ul>
-
-All of the examples were last tested with the following configuration (9/1/2000):
-
-<ul>
-<li>Sparc Solaris 2.8.
-<li>gcc-2.95.2
-<li>Python 1.6b1.
-</ul>
+For Python 3, set the environment variable <tt>PY3=1</tt>.
+This will ensure the 2to3 program is run prior to running any example.
 
+<p>
 Your mileage may vary.  If you experience a problem, please let us know by 
 contacting us on the <a href="http://www.swig.org/mail.html">mailing lists</a>.
 </body>

Examples/python/multimap/example.i

@@ -38,27 +38,44 @@ extern int    gcd(int x, int y);
     }
 %#if PY_VERSION_HEX >= 0x03000000
     {
-    int l;
-    $2[i] = PyUnicode_AsStringAndSize(s, &l);
+      PyObject *utf8str = PyUnicode_AsUTF8String(s);
+      const char *cstr = PyBytes_AsString(utf8str);
+      $2[i] = strdup(cstr);
+      Py_DECREF(utf8str);
     }
 %#else
     $2[i] = PyString_AsString(s);
 %#endif
-
   }
   $2[i] = 0;
 }
 
+%typemap(freearg) (int argc, char *argv[]) {
+%#if PY_VERSION_HEX >= 0x03000000
+  int i;
+  for (i = 0; i < $1; i++) {
+    free($2[i]);
+  }
+%#endif
+}
+
 extern int gcdmain(int argc, char *argv[]);
 
 %typemap(in) (char *bytes, int len) {
 
 %#if PY_VERSION_HEX >= 0x03000000
+  char *cstr;
+  Py_ssize_t len;
+  PyObject *utf8str;
   if (!PyUnicode_Check($input)) {
     PyErr_SetString(PyExc_ValueError,"Expected a string");
     return NULL;
   }
-  $1 = PyUnicode_AsStringAndSize($input, &$2);
+  utf8str = PyUnicode_AsUTF8String($input);
+  PyBytes_AsStringAndSize(utf8str, &cstr, &len);
+  $1 = strndup(cstr, (size_t)len);
+  $2 = (int)len;
+  Py_DECREF(utf8str);
 %#else
   if (!PyString_Check($input)) {
     PyErr_SetString(PyExc_ValueError,"Expected a string");
@@ -69,6 +86,12 @@ extern int gcdmain(int argc, char *argv[]);
 %#endif
 }
 
+%typemap(freearg) (char *bytes, int len) {
+%#if PY_VERSION_HEX >= 0x03000000
+  free($1);
+%#endif
+}
+
 extern int count(char *bytes, int len, char c);
 
 
@@ -79,13 +102,17 @@ extern int count(char *bytes, int len, char c);
 
 %typemap(in) (char *str, int len) {
 %#if PY_VERSION_HEX >= 0x03000000
-   $2 = PyUnicode_GetSize($input);
-   $1 = (char *) malloc($2+1);
-   memmove($1,PyUnicode_AsString($input),$2);
+  char *cstr;
+  Py_ssize_t len;
+  PyObject *utf8str = PyUnicode_AsUTF8String($input);
+  PyBytes_AsStringAndSize(utf8str, &cstr, &len);
+  $1 = strndup(cstr, (size_t)len);
+  $2 = (int)len;
+  Py_DECREF(utf8str);
 %#else
-   $2 = PyString_Size($input);
-   $1 = (char *) malloc($2+1);
-   memmove($1,PyString_AsString($input),$2);
+  $2 = PyString_Size($input);
+  $1 = (char *) malloc($2+1);
+  memmove($1,PyString_AsString($input),$2);
 %#endif
 }
 

Examples/python/varargs/example.i

@@ -32,9 +32,6 @@ int printf(const char *fmt, ...);
 }
 #endif
 
-/* Typemap just to make the example work */
-%typemap(in) FILE * "$1 = PyFile_AsFile($input);";
-
 int fprintf(FILE *, const char *fmt, ...);
 
 /* Here is somewhat different example.  A variable length argument
@@ -48,6 +45,13 @@ int fprintf(FILE *, const char *fmt, ...);
 %varargs(20, char *x = NULL) printv;
 
 %inline %{
+
+/* In Python 2 we could use PyFile_AsFile for converting Python sys.stdout to C's stdout.
+   This API disappeared in Python 3, so instead we use a helper function to get stdout */
+FILE * stdout_stream(void) {
+  return stdout;
+}
+
 void printv(char *s, ...) {
     va_list ap;
     char *x;

Examples/python/varargs/runme.py

@@ -13,13 +13,14 @@ for i in range(0,10):
 # This will probably be garbled because %d is interpreted by C
 example.printf("The value is %d\n")
 
+stdout = example.stdout_stream()
 # Call fprintf
-example.fprintf(sys.stdout,"Hello World. I'm fprintf\n")
+example.fprintf(stdout,"Hello World. I'm fprintf\n")
 for i in range(0,10):
-    example.fprintf(sys.stdout,"i is %d\n" % i)
+    example.fprintf(stdout,"i is %d\n" % i)
 
 # This won't be garbled since %d is not interpreted
-example.fprintf(sys.stdout,"The value is %d\n")
+example.fprintf(stdout,"The value is %d\n")
 
 # This function calls our NULL-terminated function