--- JSON-XS/XS.pm	2009/01/21 05:34:08	1.114
+++ JSON-XS/XS.pm	2009/08/09 16:01:39	1.124
@@ -101,10 +101,9 @@
 
 package JSON::XS;
 
-no warnings;
-use strict;
+use common::sense;
 
-our $VERSION = '2.231';
+our $VERSION = '2.25';
 our @ISA = qw(Exporter);
 
 our @EXPORT = qw(encode_json decode_json to_json from_json);
@@ -444,6 +443,8 @@
 
 This setting has no effect when decoding JSON texts.
 
+This setting has currently no effect on tied hashes.
+
 =item $json = $json->allow_nonref ([$enable])
 
 =item $enabled = $json->get_allow_nonref
@@ -1187,6 +1188,71 @@
 =back
 
 
+=head2 JSON and ECMAscript
+
+JSON syntax is based on how literals are represented in javascript (the
+not-standardised predecessor of ECMAscript) which is presumably why it is
+called "JavaScript Object Notation".
+
+However, JSON is not a subset (and also not a superset of course) of
+ECMAscript (the standard) or javascript (whatever browsers actually
+implement).
+
+If you want to use javascript's C<eval> function to "parse" JSON, you
+might run into parse errors for valid JSON texts, or the resulting data
+structure might not be queryable:
+
+One of the problems is that U+2028 and U+2029 are valid characters inside
+JSON strings, but are not allowed in ECMAscript string literals, so the
+following Perl fragment will not output something that can be guaranteed
+to be parsable by javascript's C<eval>:
+
+   use JSON::XS;
+
+   print encode_json [chr 0x2028];
+
+The right fix for this is to use a proper JSON parser in your javascript
+programs, and not rely on C<eval> (see for example Douglas Crockford's
+F<json2.js> parser).
+
+If this is not an option, you can, as a stop-gap measure, simply encode to
+ASCII-only JSON:
+
+   use JSON::XS;
+
+   print JSON::XS->new->ascii->encode ([chr 0x2028]);
+
+Note that this will enlarge the resulting JSON text quite a bit if you
+have many non-ASCII characters. You might be tempted to run some regexes
+to only escape U+2028 and U+2029, e.g.:
+
+   # DO NOT USE THIS!
+   my $json = JSON::XS->new->utf8->encode ([chr 0x2028]);
+   $json =~ s/\xe2\x80\xa8/\\u2028/g; # escape U+2028
+   $json =~ s/\xe2\x80\xa9/\\u2029/g; # escape U+2029
+   print $json;
+
+Note that I<this is a bad idea>: the above only works for U+2028 and
+U+2029 and thus only for fully ECMAscript-compliant parsers. Many existing
+javascript implementations, however, have issues with other characters as
+well - using C<eval> naively simply I<will> cause problems.
+
+Another problem is that some javascript implementations reserve
+some property names for their own purposes (which probably makes
+them non-ECMAscript-compliant). For example, Iceweasel reserves the
+C<__proto__> property name for it's own purposes.
+
+If that is a problem, you could parse try to filter the resulting JSON
+output for these property strings, e.g.:
+
+   $json =~ s/"__proto__"\s*:/"__proto__renamed":/g;
+
+This works because C<__proto__> is not valid outside of strings, so every
+occurence of C<"__proto__"\s*:> must be a string used as property name.
+
+If you know of other incompatibilities, please let me know.
+
+
 =head2 JSON and YAML
 
 You often hear that JSON is a subset of YAML. This is, however, a mass
@@ -1204,12 +1270,12 @@
 This will I<usually> generate JSON texts that also parse as valid
 YAML. Please note that YAML has hardcoded limits on (simple) object key
 lengths that JSON doesn't have and also has different and incompatible
-unicode handling, so you should make sure that your hash keys are
-noticeably shorter than the 1024 "stream characters" YAML allows and that
-you do not have characters with codepoint values outside the Unicode BMP
-(basic multilingual page). YAML also does not allow C<\/> sequences in
-strings (which JSON::XS does not I<currently> generate, but other JSON
-generators might).
+unicode character escape syntax, so you should make sure that your hash
+keys are noticeably shorter than the 1024 "stream characters" YAML allows
+and that you do not have characters with codepoint values outside the
+Unicode BMP (basic multilingual page). YAML also does not allow C<\/>
+sequences in strings (which JSON::XS does not I<currently> generate, but
+other JSON generators might).
 
 There might be other incompatibilities that I am not aware of (or the YAML
 specification has been changed yet again - it does so quite often). In
@@ -1238,6 +1304,12 @@
 real compatibility for many I<years> and trying to silence people who
 point out that it isn't true.
 
+Addendum/2009: the YAML 1.2 spec is still incomaptible with JSON, even
+though the incompatibilities have been documented (and are known to
+Brian) for many years and the spec makes explicit claims that YAML is a
+superset of JSON. It would be so easy to fix, but apparently, bullying and
+corrupting userdata is so much easier.
+
 =back