Index: include/ruby/intern.h
===================================================================
--- include/ruby/intern.h	(リビジョン 27929)
+++ include/ruby/intern.h	(作業コピー)
@@ -664,6 +664,7 @@
 void rb_str_update(VALUE, long, long, VALUE);
 VALUE rb_str_replace(VALUE, VALUE);
 VALUE rb_str_inspect(VALUE);
+VALUE rb_str_inspect_encode(VALUE);
 VALUE rb_str_dump(VALUE);
 VALUE rb_str_split(VALUE, const char*);
 void rb_str_associate(VALUE, VALUE);
Index: object.c
===================================================================
--- object.c	(リビジョン 27929)
+++ object.c	(作業コピー)
@@ -350,7 +350,7 @@
 VALUE
 rb_inspect(VALUE obj)
 {
-    return rb_obj_as_string(rb_funcall(obj, id_inspect, 0, 0));
+    return rb_str_inspect_encode(rb_obj_as_string(rb_funcall(obj, id_inspect, 0, 0)));
 }
 
 static int
Index: string.c
===================================================================
--- string.c	(リビジョン 27929)
+++ string.c	(作業コピー)
@@ -4078,8 +4078,101 @@
 }
 #endif
 
+
+
+static rb_encoding *
+inspect_encoding(void)
+{
+    rb_encoding *resenc = rb_default_internal_encoding();
+    if (resenc == NULL) resenc = rb_default_external_encoding();
+    if (!rb_enc_asciicompat(resenc)) resenc = rb_usascii_encoding();
+    return resenc;
+}
+
+
 /*
  * call-seq:
+ *   str.inspect_encode   -> string
+ *
+ * Returns a inspect encoding version of _str_. 
+ * if original encoding is diffrent from the result, transcode to 7bit clean.
+ *
+ *    Encoding.default_internal = "utf-8"
+ *    class A ; def inspect ; "\u3042".encode("euc-jp") end ; end
+ *    A.new                                 #=> "\xA4\xA2"
+ *    A.new.inspect                         #=> "\"\\x{A4A2}\""
+ *    A.new.inspect.inspect_encode          #=> "\"\\\\x{A4A2}\""
+ *
+ */
+
+VALUE
+rb_str_inspect_encode(VALUE str)
+{
+    rb_encoding *enc = STR_ENC_GET(str);
+    rb_encoding *resenc = inspect_encoding();
+    int unicode_p = rb_enc_unicode_p(enc);
+    VALUE result = rb_str_buf_new(0);
+#define CHAR_ESC_LEN 13 /* sizeof(\x{ hex of 32bit unsigned int } \0) */
+    char buf[CHAR_ESC_LEN + 1];
+    const char *p, *pend, *prev;
+
+    if(resenc == enc)
+	return str;
+
+    rb_enc_associate(result, resenc);
+    p = RSTRING_PTR(str); pend = RSTRING_END(str);
+    prev = p;
+    while (p < pend) {
+	unsigned int c;
+	int n;
+        n = rb_enc_precise_mbclen(p, pend, enc);
+        if (!MBCLEN_CHARFOUND_P(n)) {
+	    if (p > prev) str_buf_cat(result, prev, p - prev);
+            n = rb_enc_mbminlen(enc);
+            if (pend < p + n)
+                n = (int)(pend - p);
+            while (n--) {
+                snprintf(buf, CHAR_ESC_LEN, "\\x%02X", *p & 0377);
+                str_buf_cat(result, buf, strlen(buf));
+                prev = ++p;
+            }
+	    continue;
+	}
+	
+        n = MBCLEN_CHARFOUND_LEN(n);
+	c = rb_enc_mbc_to_codepoint(p, pend, enc);
+	p += n;
+	if ( !rb_enc_isascii(c, enc)) {
+	    if (p - n > prev) str_buf_cat(result, prev, p - n - prev);
+	    if (unicode_p) {
+		if (c < 0x10000) {
+		    snprintf(buf, CHAR_ESC_LEN, "\\u%04X", c);
+		}
+		else {
+		    snprintf(buf, CHAR_ESC_LEN, "\\u{%X}", c);
+		}
+		str_buf_cat(result, buf, strlen(buf));
+	    }
+	    else {
+		if (c < 0x100) {
+		    snprintf(buf, CHAR_ESC_LEN, "\\x%02X", c);
+		}
+		else {
+		    snprintf(buf, CHAR_ESC_LEN, "\\x{%X}", c);
+		}
+		str_buf_cat(result, buf, strlen(buf));
+	    }
+	    prev = p;
+	}
+    }
+    if (p > prev) str_buf_cat(result, prev, p - prev);
+    OBJ_INFECT(result, str);
+    return result;
+}
+#undef CHAR_ESC_LEN
+
+/*
+ * call-seq:
  *   str.inspect   -> string
  *
  * Returns a printable version of _str_, surrounded by quote marks,
@@ -4098,11 +4191,8 @@
 #define CHAR_ESC_LEN 13 /* sizeof(\x{ hex of 32bit unsigned int } \0) */
     char buf[CHAR_ESC_LEN + 1];
     VALUE result = rb_str_buf_new(0);
-    rb_encoding *resenc = rb_default_internal_encoding();
+    rb_encoding *resenc = inspect_encoding();
     int unicode_p = rb_enc_unicode_p(enc);
-
-    if (resenc == NULL) resenc = rb_default_external_encoding();
-    if (!rb_enc_asciicompat(resenc)) resenc = rb_usascii_encoding();
     rb_enc_associate(result, resenc);
     str_buf_cat2(result, "\"");
 
@@ -7417,6 +7507,7 @@
     rb_define_method(rb_cString, "to_s", rb_str_to_s, 0);
     rb_define_method(rb_cString, "to_str", rb_str_to_s, 0);
     rb_define_method(rb_cString, "inspect", rb_str_inspect, 0);
+    rb_define_method(rb_cString, "inspect_encode", rb_str_inspect_encode, 0);
     rb_define_method(rb_cString, "dump", rb_str_dump, 0);
 
     rb_define_method(rb_cString, "upcase", rb_str_upcase, 0);