#2630: Implement PEP 3138.

The repr() of a string now contains printable Unicode characters unescaped.
The new ascii() builtin can be used to get a repr() with only ASCII characters in it.

PEP and patch were written by Atsuo Ishimoto.

Objects/stringlib/string_format.h

@@ -766,6 +766,10 @@ do_conversion(PyObject *obj, STRINGLIB_CHAR conversion)
         return PyObject_Repr(obj);
     case 's':
         return STRINGLIB_TOSTR(obj);
+#if PY_VERSION_HEX >= 0x03000000
+    case 'a':
+        return STRINGLIB_TOASCII(obj);
+#endif
     default:
 	if (conversion > 32 && conversion < 127) {
 		/* It's the ASCII subrange; casting to char is safe

Objects/stringlib/stringdefs.h

@@ -24,5 +24,5 @@
 #define STRINGLIB_CMP            memcmp
 #define STRINGLIB_TOSTR          PyObject_Str
 #define STRINGLIB_GROUPING       _PyBytes_InsertThousandsGrouping
-
+#define STRINGLIB_TOASCII        PyObject_Repr
 #endif /* !STRINGLIB_STRINGDEFS_H */

Objects/stringlib/unicodedefs.h

@@ -25,8 +25,10 @@
 
 #if PY_VERSION_HEX < 0x03000000
 #define STRINGLIB_TOSTR          PyObject_Unicode
+#define STRINGLIB_TOASCII        PyObject_Repr
 #else
 #define STRINGLIB_TOSTR          PyObject_Str
+#define STRINGLIB_TOASCII        PyObject_ASCII
 #endif
 
 #define STRINGLIB_WANT_CONTAINS_OBJ 1