[ViewVC] Diff of: cvs/JSON-XS/README

Comparing JSON-XS/README (file contents):
Revision 1.34 by root, Thu Mar 11 17:36:09 2010 UTC vs.
Revision 1.38 by root, Tue Oct 29 00:36:18 2013 UTC

…		…
56	does so, and even documents what "correct" means.	56	does so, and even documents what "correct" means.
57		57
58	* round-trip integrity	58	* round-trip integrity
59		59
60	When you serialise a perl data structure using only data types	60	When you serialise a perl data structure using only data types
61	supported by JSON, the deserialised data structure is identical on	61	supported by JSON and Perl, the deserialised data structure is
62	the Perl level. (e.g. the string "2.0" doesn't suddenly become "2"	62	identical on the Perl level. (e.g. the string "2.0" doesn't suddenly
63	just because it looks like a number). There minor are exceptions	63	become "2" just because it looks like a number). There are minor
64	to this, read the MAPPING section below to learn about those.	64	exceptions to this, read the MAPPING section below to learn about
		65	those.
65		66
66	* strict checking of JSON correctness	67	* strict checking of JSON correctness
67		68
68	There is no guessing, no generating of illegal JSON texts by	69	There is no guessing, no generating of illegal JSON texts by
69	default, and only JSON is accepted as input by default (the latter	70	default, and only JSON is accepted as input by default (the latter
…		…
76	too.	77	too.
77		78
78	* simple to use	79	* simple to use
79		80
80	This module has both a simple functional interface as well as an	81	This module has both a simple functional interface as well as an
81	object oriented interface interface.	82	object oriented interface.
82		83
83	* reasonably versatile output formats	84	* reasonably versatile output formats
84		85
85	You can choose between the most compact guaranteed-single-line	86	You can choose between the most compact guaranteed-single-line
86	format possible (nice for simple line-based protocols), a pure-ASCII	87	format possible (nice for simple line-based protocols), a pure-ASCII
…		…
111	This function call is functionally identical to:	112	This function call is functionally identical to:
112		113
113	$perl_scalar = JSON::XS->new->utf8->decode ($json_text)	114	$perl_scalar = JSON::XS->new->utf8->decode ($json_text)
114		115
115	Except being faster.	116	Except being faster.
116
117	$is_boolean = JSON::XS::is_bool $scalar
118	Returns true if the passed scalar represents either JSON::XS::true
119	or JSON::XS::false, two constants that act like 1 and 0,
120	respectively and are used to represent JSON "true" and "false"
121	values in Perl.
122
123	See MAPPING, below, for more information on how JSON values are
124	mapped to Perl.
125		117
126	A FEW NOTES ON UNICODE AND PERL	118	A FEW NOTES ON UNICODE AND PERL
127	Since this often leads to confusion, here are a few very clear words on	119	Since this often leads to confusion, here are a few very clear words on
128	how Unicode works in Perl, modulo bugs.	120	how Unicode works in Perl, modulo bugs.
129		121
…		…
368	output JSON objects by sorting their keys. This is adding a	360	output JSON objects by sorting their keys. This is adding a
369	comparatively high overhead.	361	comparatively high overhead.
370		362
371	If $enable is false, then the "encode" method will output key-value	363	If $enable is false, then the "encode" method will output key-value
372	pairs in the order Perl stores them (which will likely change	364	pairs in the order Perl stores them (which will likely change
373	between runs of the same script).	365	between runs of the same script, and can change even within the same
		366	run from 5.18 onwards).
374		367
375	This option is useful if you want the same data structure to be	368	This option is useful if you want the same data structure to be
376	encoded as the same JSON text (given the same overall settings). If	369	encoded as the same JSON text (given the same overall settings). If
377	it is disabled, the same hash might be encoded differently even if	370	it is disabled, the same hash might be encoded differently even if
378	contains the same data, as key-value pairs have no inherent ordering	371	contains the same data, as key-value pairs have no inherent ordering
…		…
415	recommended to leave it off unless you know your communications	408	recommended to leave it off unless you know your communications
416	partner.	409	partner.
417		410
418	$json = $json->allow_blessed ([$enable])	411	$json = $json->allow_blessed ([$enable])
419	$enabled = $json->get_allow_blessed	412	$enabled = $json->get_allow_blessed
		413	See "OBJECT SERIALISATION" for details.
		414
420	If $enable is true (or missing), then the "encode" method will not	415	If $enable is true (or missing), then the "encode" method will not
421	barf when it encounters a blessed reference. Instead, the value of	416	barf when it encounters a blessed reference that it cannot convert
422	the convert_blessed option will decide whether "null"	417	otherwise. Instead, a JSON "null" value is encoded instead of the
423	("convert_blessed" disabled or no "TO_JSON" method found) or a	418	object.
424	representation of the object ("convert_blessed" enabled and
425	"TO_JSON" method found) is being encoded. Has no effect on "decode".
426		419
427	If $enable is false (the default), then "encode" will throw an	420	If $enable is false (the default), then "encode" will throw an
428	exception when it encounters a blessed object.	421	exception when it encounters a blessed object that it cannot convert
		422	otherwise.
		423
		424	This setting has no effect on "decode".
429		425
430	$json = $json->convert_blessed ([$enable])	426	$json = $json->convert_blessed ([$enable])
431	$enabled = $json->get_convert_blessed	427	$enabled = $json->get_convert_blessed
		428	See "OBJECT SERIALISATION" for details.
		429
432	If $enable is true (or missing), then "encode", upon encountering a	430	If $enable is true (or missing), then "encode", upon encountering a
433	blessed object, will check for the availability of the "TO_JSON"	431	blessed object, will check for the availability of the "TO_JSON"
434	method on the object's class. If found, it will be called in scalar	432	method on the object's class. If found, it will be called in scalar
435	context and the resulting scalar will be encoded instead of the	433	context and the resulting scalar will be encoded instead of the
436	object. If no "TO_JSON" method is found, the value of	434	object.
437	"allow_blessed" will decide what to do.
438		435
439	The "TO_JSON" method may safely call die if it wants. If "TO_JSON"	436	The "TO_JSON" method may safely call die if it wants. If "TO_JSON"
440	returns other blessed objects, those will be handled in the same	437	returns other blessed objects, those will be handled in the same
441	way. "TO_JSON" must take care of not causing an endless recursion	438	way. "TO_JSON" must take care of not causing an endless recursion
442	cycle (== crash) in this case. The name of "TO_JSON" was chosen	439	cycle (== crash) in this case. The name of "TO_JSON" was chosen
443	because other methods called by the Perl core (== not by the user of	440	because other methods called by the Perl core (== not by the user of
444	the object) are usually in upper case letters and to avoid	441	the object) are usually in upper case letters and to avoid
445	collisions with any "to_json" function or method.	442	collisions with any "to_json" function or method.
446		443
447	This setting does not yet influence "decode" in any way, but in the	444	If $enable is false (the default), then "encode" will not consider
448	future, global hooks might get installed that influence "decode" and	445	this type of conversion.
449	are enabled by this setting.
450		446
451	If $enable is false, then the "allow_blessed" setting will decide	447	This setting has no effect on "decode".
452	what to do when a blessed object is found.	448
		449	$json = $json->allow_tags ([$enable])
		450	$enabled = $json->allow_tags
		451	See "OBJECT SERIALISATION" for details.
		452
		453	If $enable is true (or missing), then "encode", upon encountering a
		454	blessed object, will check for the availability of the "FREEZE"
		455	method on the object's class. If found, it will be used to serialise
		456	the object into a nonstandard tagged JSON value (that JSON decoders
		457	cannot decode).
		458
		459	It also causes "decode" to parse such tagged JSON values and
		460	deserialise them via a call to the "THAW" method.
		461
		462	If $enable is false (the default), then "encode" will not consider
		463	this type of conversion, and tagged JSON values will cause a parse
		464	error in "decode", as if tags were not part of the grammar.
453		465
454	$json = $json->filter_json_object ([$coderef->($hashref)])	466	$json = $json->filter_json_object ([$coderef->($hashref)])
455	When $coderef is specified, it will be called from "decode" each	467	When $coderef is specified, it will be called from "decode" each
456	time it decodes a JSON object. The only argument is a reference to	468	time it decodes a JSON object. The only argument is a reference to
457	the newly-created hash. If the code references returns a single	469	the newly-created hash. If the code references returns a single
…		…
593		605
594	See SECURITY CONSIDERATIONS, below, for more info on why this is	606	See SECURITY CONSIDERATIONS, below, for more info on why this is
595	useful.	607	useful.
596		608
597	$json_text = $json->encode ($perl_scalar)	609	$json_text = $json->encode ($perl_scalar)
598	Converts the given Perl data structure (a simple scalar or a	610	Converts the given Perl value or data structure to its JSON
599	reference to a hash or array) to its JSON representation. Simple	611	representation. Croaks on error.
600	scalars will be converted into JSON string or number sequences,
601	while references to arrays become JSON arrays and references to
602	hashes become JSON objects. Undefined Perl values (e.g. "undef")
603	become JSON "null" values. Neither "true" nor "false" values will be
604	generated.
605		612
606	$perl_scalar = $json->decode ($json_text)	613	$perl_scalar = $json->decode ($json_text)
607	The opposite of "encode": expects a JSON text and tries to parse it,	614	The opposite of "encode": expects a JSON text and tries to parse it,
608	returning the resulting simple scalar or reference. Croaks on error.	615	returning the resulting simple scalar or reference. Croaks on error.
609
610	JSON numbers and strings become simple Perl scalars. JSON arrays
611	become Perl arrayrefs and JSON objects become Perl hashrefs. "true"
612	becomes 1, "false" becomes 0 and "null" becomes "undef".
613		616
614	($perl_scalar, $characters) = $json->decode_prefix ($json_text)	617	($perl_scalar, $characters) = $json->decode_prefix ($json_text)
615	This works like the "decode" method, but instead of raising an	618	This works like the "decode" method, but instead of raising an
616	exception when there is trailing garbage after the first JSON	619	exception when there is trailing garbage after the first JSON
617	object, it will silently stop parsing there and return the number of	620	object, it will silently stop parsing there and return the number of
618	characters consumed so far.	621	characters consumed so far.
619		622
620	This is useful if your JSON texts are not delimited by an outer	623	This is useful if your JSON texts are not delimited by an outer
621	protocol (which is not the brightest thing to do in the first place)
622	and you need to know where the JSON text ends.	624	protocol and you need to know where the JSON text ends.
623		625
624	JSON::XS->new->decode_prefix ("[1] the tail")	626	JSON::XS->new->decode_prefix ("[1] the tail")
625	=> ([], 3)	627	=> ([], 3)
626		628
627	INCREMENTAL PARSING	629	INCREMENTAL PARSING
…		…
635	calls).	637	calls).
636		638
637	JSON::XS will only attempt to parse the JSON text once it is sure it has	639	JSON::XS will only attempt to parse the JSON text once it is sure it has
638	enough text to get a decisive result, using a very simple but truly	640	enough text to get a decisive result, using a very simple but truly
639	incremental parser. This means that it sometimes won't stop as early as	641	incremental parser. This means that it sometimes won't stop as early as
640	the full parser, for example, it doesn't detect parenthese mismatches.	642	the full parser, for example, it doesn't detect mismatched parentheses.
641	The only thing it guarantees is that it starts decoding as soon as a	643	The only thing it guarantees is that it starts decoding as soon as a
642	syntactically valid JSON text has been seen. This means you need to set	644	syntactically valid JSON text has been seen. This means you need to set
643	resource limits (e.g. "max_size") to ensure the parser will stop parsing	645	resource limits (e.g. "max_size") to ensure the parser will stop parsing
644	in the presence if syntax errors.	646	in the presence if syntax errors.
645		647
…		…
659		661
660	If the method is called in scalar context, then it will try to	662	If the method is called in scalar context, then it will try to
661	extract exactly one JSON object. If that is successful, it will	663	extract exactly one JSON object. If that is successful, it will
662	return this object, otherwise it will return "undef". If there is a	664	return this object, otherwise it will return "undef". If there is a
663	parse error, this method will croak just as "decode" would do (one	665	parse error, this method will croak just as "decode" would do (one
664	can then use "incr_skip" to skip the errornous part). This is the	666	can then use "incr_skip" to skip the erroneous part). This is the
665	most common way of using the method.	667	most common way of using the method.
666		668
667	And finally, in list context, it will try to extract as many objects	669	And finally, in list context, it will try to extract as many objects
668	from the stream as it can find and return them, or the empty list	670	from the stream as it can find and return them, or the empty list
669	otherwise. For this to work, there must be no separators between the	671	otherwise. For this to work, there must be no separators between the
670	JSON objects or arrays, instead they must be concatenated	672	JSON objects or arrays, instead they must be concatenated
671	back-to-back. If an error occurs, an exception will be raised as in	673	back-to-back. If an error occurs, an exception will be raised as in
672	the scalar context case. Note that in this case, any	674	the scalar context case. Note that in this case, any
673	previously-parsed JSON texts will be lost.	675	previously-parsed JSON texts will be lost.
		676
		677	Example: Parse some JSON arrays/objects in a given string and return
		678	them.
		679
		680	my @objs = JSON::XS->new->incr_parse ("[5][7][1,2]");
674		681
675	$lvalue_string = $json->incr_text	682	$lvalue_string = $json->incr_text
676	This method returns the currently stored JSON fragment as an lvalue,	683	This method returns the currently stored JSON fragment as an lvalue,
677	that is, you can manipulate it. This only works when a preceding	684	that is, you can manipulate it. This only works when a preceding
678	call to "incr_parse" in scalar context successfully returned an	685	call to "incr_parse" in scalar context successfully returned an
…		…
692	"incr_parse" died, in which case the input buffer and incremental	699	"incr_parse" died, in which case the input buffer and incremental
693	parser state is left unchanged, to skip the text parsed so far and	700	parser state is left unchanged, to skip the text parsed so far and
694	to reset the parse state.	701	to reset the parse state.
695		702
696	The difference to "incr_reset" is that only text until the parse	703	The difference to "incr_reset" is that only text until the parse
697	error occured is removed.	704	error occurred is removed.
698		705
699	$json->incr_reset	706	$json->incr_reset
700	This completely resets the incremental parser, that is, after this	707	This completely resets the incremental parser, that is, after this
701	call, it will be as if the parser had never parsed anything.	708	call, it will be as if the parser had never parsed anything.
702		709
…		…
886	If the number consists of digits only, JSON::XS will try to	893	If the number consists of digits only, JSON::XS will try to
887	represent it as an integer value. If that fails, it will try to	894	represent it as an integer value. If that fails, it will try to
888	represent it as a numeric (floating point) value if that is possible	895	represent it as a numeric (floating point) value if that is possible
889	without loss of precision. Otherwise it will preserve the number as	896	without loss of precision. Otherwise it will preserve the number as
890	a string value (in which case you lose roundtripping ability, as the	897	a string value (in which case you lose roundtripping ability, as the
891	JSON number will be re-encoded toa JSON string).	898	JSON number will be re-encoded to a JSON string).
892		899
893	Numbers containing a fractional or exponential part will always be	900	Numbers containing a fractional or exponential part will always be
894	represented as numeric (floating point) values, possibly at a loss	901	represented as numeric (floating point) values, possibly at a loss
895	of precision (in which case you might lose perfect roundtripping	902	of precision (in which case you might lose perfect roundtripping
896	ability, but the JSON number will still be re-encoded as a JSON	903	ability, but the JSON number will still be re-encoded as a JSON
897	number).	904	number).
898		905
		906	Note that precision is not accuracy - binary floating point values
		907	cannot represent most decimal fractions exactly, and when converting
		908	from and to floating point, JSON::XS only guarantees precision up to
		909	but not including the least significant bit.
		910
899	true, false	911	true, false
900	These JSON atoms become "JSON::XS::true" and "JSON::XS::false",	912	These JSON atoms become "Types::Serialiser::true" and
901	respectively. They are overloaded to act almost exactly like the	913	"Types::Serialiser::false", respectively. They are overloaded to act
902	numbers 1 and 0. You can check whether a scalar is a JSON boolean by	914	almost exactly like the numbers 1 and 0. You can check whether a
903	using the "JSON::XS::is_bool" function.	915	scalar is a JSON boolean by using the "Types::Serialiser::is_bool"
		916	function (after "use Types::Serialier", of course).
904		917
905	null	918	null
906	A JSON null atom becomes "undef" in Perl.	919	A JSON null atom becomes "undef" in Perl.
		920
		921	shell-style comments ("# text")
		922	As a nonstandard extension to the JSON syntax that is enabled by the
		923	"relaxed" setting, shell-style comments are allowed. They can start
		924	anywhere outside strings and go till the end of the line.
		925
		926	tagged values ("(tag)value").
		927	Another nonstandard extension to the JSON syntax, enabled with the
		928	"allow_tags" setting, are tagged values. In this implementation, the
		929	tag must be a perl package/class name encoded as a JSON string,
		930	and the value must be a JSON array encoding optional constructor
		931	arguments.
		932
		933	See "OBJECT SERIALISATION", below, for details.
907		934
908	PERL -> JSON	935	PERL -> JSON
909	The mapping from Perl to JSON is slightly more difficult, as Perl is a	936	The mapping from Perl to JSON is slightly more difficult, as Perl is a
910	truly typeless language, so we can only guess which JSON type is meant	937	truly typeless language, so we can only guess which JSON type is meant
911	by a Perl value.	938	by a Perl value.
912		939
913	hash references	940	hash references
914	Perl hash references become JSON objects. As there is no inherent	941	Perl hash references become JSON objects. As there is no inherent
915	ordering in hash keys (or JSON objects), they will usually be	942	ordering in hash keys (or JSON objects), they will usually be
916	encoded in a pseudo-random order that can change between runs of the	943	encoded in a pseudo-random order. JSON::XS can optionally sort the
917	same program but stays generally the same within a single run of a	944	hash keys (determined by the canonical flag), so the same
918	program. JSON::XS can optionally sort the hash keys (determined by	945	datastructure will serialise to the same JSON text (given same
919	the canonical flag), so the same datastructure will serialise to	946	settings and version of JSON::XS), but this incurs a runtime
920	the same JSON text (given same settings and version of JSON::XS),	947	overhead and is only rarely useful, e.g. when you want to compare
921	but this incurs a runtime overhead and is only rarely useful, e.g.	948	some JSON text against another for equality.
922	when you want to compare some JSON text against another for
923	equality.
924		949
925	array references	950	array references
926	Perl array references become JSON arrays.	951	Perl array references become JSON arrays.
927		952
928	other references	953	other references
929	Other unblessed references are generally not allowed and will cause	954	Other unblessed references are generally not allowed and will cause
930	an exception to be thrown, except for references to the integers 0	955	an exception to be thrown, except for references to the integers 0
931	and 1, which get turned into "false" and "true" atoms in JSON. You	956	and 1, which get turned into "false" and "true" atoms in JSON.
932	can also use "JSON::XS::false" and "JSON::XS::true" to improve	957
		958	Since "JSON::XS" uses the boolean model from Types::Serialiser, you
		959	can also "use Types::Serialiser" and then use
		960	"Types::Serialiser::false" and "Types::Serialiser::true" to improve
933	readability.	961	readability.
934		962
		963	use Types::Serialiser;
935	encode_json [\0, JSON::XS::true] # yields [false,true]	964	encode_json [\0, Types::Serialiser::true] # yields [false,true]
936		965
937	JSON::XS::true, JSON::XS::false	966	Types::Serialiser::true, Types::Serialiser::false
938	These special values become JSON true and JSON false values,	967	These special values from the Types::Serialiser module become JSON
939	respectively. You can also use "\1" and "\0" directly if you want.	968	true and JSON false values, respectively. You can also use "\1" and
		969	"\0" directly if you want.
940		970
941	blessed objects	971	blessed objects
942	Blessed objects are not directly representable in JSON. See the	972	Blessed objects are not directly representable in JSON, but
943	"allow_blessed" and "convert_blessed" methods on various options on	973	"JSON::XS" allows various ways of handling objects. See "OBJECT
944	how to deal with this: basically, you can choose between throwing an	974	SERIALISATION", below, for details.
945	exception, encoding the reference as if it weren't blessed, or
946	provide your own serialiser method.
947		975
948	simple scalars	976	simple scalars
949	Simple Perl scalars (any scalar that is not a reference) are the	977	Simple Perl scalars (any scalar that is not a reference) are the
950	most difficult objects to encode: JSON::XS will encode undefined	978	most difficult objects to encode: JSON::XS will encode undefined
951	scalars as JSON "null" values, scalars that have last been used in a	979	scalars as JSON "null" values, scalars that have last been used in a
…		…
979		1007
980	You can not currently force the type in other, less obscure, ways.	1008	You can not currently force the type in other, less obscure, ways.
981	Tell me if you need this capability (but don't forget to explain why	1009	Tell me if you need this capability (but don't forget to explain why
982	it's needed :).	1010	it's needed :).
983		1011
		1012	Note that numerical precision has the same meaning as under Perl (so
		1013	binary to decimal conversion follows the same rules as in Perl,
		1014	which can differ to other languages). Also, your perl interpreter
		1015	might expose extensions to the floating point numbers of your
		1016	platform, such as infinities or NaN's - these cannot be represented
		1017	in JSON, and it is an error to pass those in.
		1018
		1019	OBJECT SERIALISATION
		1020	As JSON cannot directly represent Perl objects, you have to choose
		1021	between a pure JSON representation (without the ability to deserialise
		1022	the object automatically again), and a nonstandard extension to the JSON
		1023	syntax, tagged values.
		1024
		1025	SERIALISATION
		1026	What happens when "JSON::XS" encounters a Perl object depends on the
		1027	"allow_blessed", "convert_blessed" and "allow_tags" settings, which are
		1028	used in this order:
		1029
		1030	1. "allow_tags" is enabled and the object has a "FREEZE" method.
		1031	In this case, "JSON::XS" uses the Types::Serialiser object
		1032	serialisation protocol to create a tagged JSON value, using a
		1033	nonstandard extension to the JSON syntax.
		1034
		1035	This works by invoking the "FREEZE" method on the object, with the
		1036	first argument being the object to serialise, and the second
		1037	argument being the constant string "JSON" to distinguish it from
		1038	other serialisers.
		1039
		1040	The "FREEZE" method can return any number of values (i.e. zero or
		1041	more). These values and the paclkage/classname of the object will
		1042	then be encoded as a tagged JSON value in the following format:
		1043
		1044	("classname")[FREEZE return values...]
		1045
		1046	For example, the hypothetical "My::Object" "FREEZE" method might use
		1047	the objects "type" and "id" members to encode the object:
		1048
		1049	sub My::Object::FREEZE {
		1050	my ($self, $serialiser) = @_;
		1051
		1052	($self->{type}, $self->{id})
		1053	}
		1054
		1055	2. "convert_blessed" is enabled and the object has a "TO_JSON" method.
		1056	In this case, the "TO_JSON" method of the object is invoked in
		1057	scalar context. It must return a single scalar that can be directly
		1058	encoded into JSON. This scalar replaces the object in the JSON text.
		1059
		1060	For example, the following "TO_JSON" method will convert all URI
		1061	objects to JSON strings when serialised. The fatc that these values
		1062	originally were URI objects is lost.
		1063
		1064	sub URI::TO_JSON {
		1065	my ($uri) = @_;
		1066	$uri->as_string
		1067	}
		1068
		1069	3. "allow_blessed" is enabled.
		1070	The object will be serialised as a JSON null value.
		1071
		1072	4. none of the above
		1073	If none of the settings are enabled or the respective methods are
		1074	missing, "JSON::XS" throws an exception.
		1075
		1076	DESERIALISATION
		1077	For deserialisation there are only two cases to consider: either
		1078	nonstandard tagging was used, in which case "allow_tags" decides, or
		1079	objects cannot be automatically be deserialised, in which case you can
		1080	use postprocessing or the "filter_json_object" or
		1081	"filter_json_single_key_object" callbacks to get some real objects our
		1082	of your JSON.
		1083
		1084	This section only considers the tagged value case: I a tagged JSON
		1085	object is encountered during decoding and "allow_tags" is disabled, a
		1086	parse error will result (as if tagged values were not part of the
		1087	grammar).
		1088
		1089	If "allow_tags" is enabled, "JSON::XS" will look up the "THAW" method of
		1090	the package/classname used during serialisation (it will not attempt to
		1091	load the package as a Perl module). If there is no such method, the
		1092	decoding will fail with an error.
		1093
		1094	Otherwise, the "THAW" method is invoked with the classname as first
		1095	argument, the constant string "JSON" as second argument, and all the
		1096	values from the JSON array (the values originally returned by the
		1097	"FREEZE" method) as remaining arguments.
		1098
		1099	The method must then return the object. While technically you can return
		1100	any Perl scalar, you might have to enable the "enable_nonref" setting to
		1101	make that work in all cases, so better return an actual blessed
		1102	reference.
		1103
		1104	As an example, let's implement a "THAW" function that regenerates the
		1105	"My::Object" from the "FREEZE" example earlier:
		1106
		1107	sub My::Object::THAW {
		1108	my ($class, $serialiser, $type, $id) = @_;
		1109
		1110	$class->new (type => $type, id => $id)
		1111	}
		1112
984	ENCODING/CODESET FLAG NOTES	1113	ENCODING/CODESET FLAG NOTES
985	The interested reader might have seen a number of flags that signify	1114	The interested reader might have seen a number of flags that signify
986	encodings or codesets - "utf8", "latin1" and "ascii". There seems to be	1115	encodings or codesets - "utf8", "latin1" and "ascii". There seems to be
987	some confusion on what these do, so here is a short comparison:	1116	some confusion on what these do, so here is a short comparison:
988		1117
…		…
1007		1136
1008	"utf8" flag disabled	1137	"utf8" flag disabled
1009	When "utf8" is disabled (the default), then "encode"/"decode"	1138	When "utf8" is disabled (the default), then "encode"/"decode"
1010	generate and expect Unicode strings, that is, characters with high	1139	generate and expect Unicode strings, that is, characters with high
1011	ordinal Unicode values (> 255) will be encoded as such characters,	1140	ordinal Unicode values (> 255) will be encoded as such characters,
1012	and likewise such characters are decoded as-is, no canges to them	1141	and likewise such characters are decoded as-is, no changes to them
1013	will be done, except "(re-)interpreting" them as Unicode codepoints	1142	will be done, except "(re-)interpreting" them as Unicode codepoints
1014	or Unicode characters, respectively (to Perl, these are the same	1143	or Unicode characters, respectively (to Perl, these are the same
1015	thing in strings unless you do funny/weird/dumb stuff).	1144	thing in strings unless you do funny/weird/dumb stuff).
1016		1145
1017	This is useful when you want to do the encoding yourself (e.g. when	1146	This is useful when you want to do the encoding yourself (e.g. when
…		…
1125	characters as well - using "eval" naively simply will cause problems.	1254	characters as well - using "eval" naively simply will cause problems.
1126		1255
1127	Another problem is that some javascript implementations reserve some	1256	Another problem is that some javascript implementations reserve some
1128	property names for their own purposes (which probably makes them	1257	property names for their own purposes (which probably makes them
1129	non-ECMAscript-compliant). For example, Iceweasel reserves the	1258	non-ECMAscript-compliant). For example, Iceweasel reserves the
1130	"__proto__" property name for it's own purposes.	1259	"__proto__" property name for its own purposes.
1131		1260
1132	If that is a problem, you could parse try to filter the resulting JSON	1261	If that is a problem, you could parse try to filter the resulting JSON
1133	output for these property strings, e.g.:	1262	output for these property strings, e.g.:
1134		1263
1135	$json =~ s/"__proto__"\s*:/"__proto__renamed":/g;	1264	$json =~ s/"__proto__"\s*:/"__proto__renamed":/g;
1136		1265
1137	This works because "__proto__" is not valid outside of strings, so every	1266	This works because "__proto__" is not valid outside of strings, so every
1138	occurence of ""__proto__"\s*:" must be a string used as property name.	1267	occurrence of ""__proto__"\s*:" must be a string used as property name.
1139		1268
1140	If you know of other incompatibilities, please let me know.	1269	If you know of other incompatibilities, please let me know.
1141		1270
1142	JSON and YAML	1271	JSON and YAML
1143	You often hear that JSON is a subset of YAML. This is, however, a mass	1272	You often hear that JSON is a subset of YAML. This is, however, a mass
…		…
1183	(which is not that difficult or long) and finally make YAML	1312	(which is not that difficult or long) and finally make YAML
1184	compatible to it, and educating users about the changes, instead of	1313	compatible to it, and educating users about the changes, instead of
1185	spreading lies about the real compatibility for many years and	1314	spreading lies about the real compatibility for many years and
1186	trying to silence people who point out that it isn't true.	1315	trying to silence people who point out that it isn't true.
1187		1316
1188	Addendum/2009: the YAML 1.2 spec is still incomaptible with JSON,	1317	Addendum/2009: the YAML 1.2 spec is still incompatible with JSON,
1189	even though the incompatibilities have been documented (and are	1318	even though the incompatibilities have been documented (and are
1190	known to Brian) for many years and the spec makes explicit claims	1319	known to Brian) for many years and the spec makes explicit claims
1191	that YAML is a superset of JSON. It would be so easy to fix, but	1320	that YAML is a superset of JSON. It would be so easy to fix, but
1192	apparently, bullying and corrupting userdata is so much easier.	1321	apparently, bullying people and corrupting userdata is so much
		1322	easier.
1193		1323
1194	SPEED	1324	SPEED
1195	It seems that JSON::XS is surprisingly fast, as shown in the following	1325	It seems that JSON::XS is surprisingly fast, as shown in the following
1196	tables. They have been generated with the help of the "eg/bench" program	1326	tables. They have been generated with the help of the "eg/bench" program
1197	in the JSON::XS distribution, to make it easy to compare on your own	1327	in the JSON::XS distribution, to make it easy to compare on your own
…		…
1293	to see whether you are vulnerable to some common attack vectors (which	1423	to see whether you are vulnerable to some common attack vectors (which
1294	really are browser design bugs, but it is still you who will have to	1424	really are browser design bugs, but it is still you who will have to
1295	deal with it, as major browser developers care only for features, not	1425	deal with it, as major browser developers care only for features, not
1296	about getting security right).	1426	about getting security right).
1297		1427
		1428	INTEROPERABILITY WITH OTHER MODULES
		1429	"JSON::XS" uses the Types::Serialiser module to provide boolean
		1430	constants. That means that the JSON true and false values will be
		1431	comaptible to true and false values of iother modules that do the same,
		1432	such as JSON::PP and CBOR::XS.
		1433
1298	THREADS	1434	THREADS
1299	This module is not guaranteed to be thread safe and there are no plans	1435	This module is not guaranteed to be thread safe and there are no plans
1300	to change this until Perl gets thread support (as opposed to the	1436	to change this until Perl gets thread support (as opposed to the
1301	horribly slow so-called "threads" which are simply slow and bloated	1437	horribly slow so-called "threads" which are simply slow and bloated
1302	process simulations - use fork, it's much faster, cheaper, better).	1438	process simulations - use fork, it's much faster, cheaper, better).
1303		1439
1304	(It might actually work, but you have been warned).	1440	(It might actually work, but you have been warned).
1305		1441
		1442	THE PERILS OF SETLOCALE
		1443	Sometimes people avoid the Perl locale support and directly call the
		1444	system's setlocale function with "LC_ALL".
		1445
		1446	This breaks both perl and modules such as JSON::XS, as stringification
		1447	of numbers no longer works correctly (e.g. "$x = 0.1; print "$x"+1"
		1448	might print 1, and JSON::XS might output illegal JSON as JSON::XS relies
		1449	on perl to stringify numbers).
		1450
		1451	The solution is simple: don't call "setlocale", or use it for only those
		1452	categories you need, such as "LC_MESSAGES" or "LC_CTYPE".
		1453
		1454	If you need "LC_NUMERIC", you should enable it only around the code that
		1455	actually needs it (avoiding stringification of numbers), and restore it
		1456	afterwards.
		1457
1306	BUGS	1458	BUGS
1307	While the goal of this module is to be correct, that unfortunately does	1459	While the goal of this module is to be correct, that unfortunately does
1308	not mean it's bug-free, only that I think its design is bug-free. If you	1460	not mean it's bug-free, only that I think its design is bug-free. If you
1309	keep reporting bugs they will be fixed swiftly, though.	1461	keep reporting bugs they will be fixed swiftly, though.
1310		1462

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Comparing JSON-XS/README (file contents): Revision 1.34 by root, Thu Mar 11 17:36:09 2010 UTC vs. Revision 1.38 by root, Tue Oct 29 00:36:18 2013 UTC

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Comparing JSON-XS/README (file contents):
Revision 1.34 by root, Thu Mar 11 17:36:09 2010 UTC vs.
Revision 1.38 by root, Tue Oct 29 00:36:18 2013 UTC