--- JSON-XS/XS.pm 2010/01/19 01:02:19 1.129 +++ JSON-XS/XS.pm 2013/05/23 09:31:32 1.139 @@ -66,10 +66,10 @@ =item * round-trip integrity When you serialise a perl data structure using only data types supported -by JSON, the deserialised data structure is identical on the Perl level. -(e.g. the string "2.0" doesn't suddenly become "2" just because it looks -like a number). There minor I exceptions to this, read the MAPPING -section below to learn about those. +by JSON and Perl, the deserialised data structure is identical on the Perl +level. (e.g. the string "2.0" doesn't suddenly become "2" just because +it looks like a number). There I minor exceptions to this, read the +MAPPING section below to learn about those. =item * strict checking of JSON correctness @@ -103,7 +103,7 @@ use common::sense; -our $VERSION = '2.28'; +our $VERSION = 2.34; our @ISA = qw(Exporter); our @EXPORT = qw(encode_json decode_json to_json from_json); @@ -434,7 +434,8 @@ If C<$enable> is false, then the C method will output key-value pairs in the order Perl stores them (which will likely change between runs -of the same script). +of the same script, and can change even within the same run from 5.18 +onwards). This option is useful if you want the same data structure to be encoded as the same JSON text (given the same overall settings). If it is disabled, @@ -715,8 +716,8 @@ JSON::XS will only attempt to parse the JSON text once it is sure it has enough text to get a decisive result, using a very simple but truly incremental parser. This means that it sometimes won't stop as -early as the full parser, for example, it doesn't detect parenthese -mismatches. The only thing it guarantees is that it starts decoding as +early as the full parser, for example, it doesn't detect mismatched +parentheses. The only thing it guarantees is that it starts decoding as soon as a syntactically valid JSON text has been seen. This means you need to set resource limits (e.g. C) to ensure the parser will stop parsing in the presence if syntax errors. @@ -753,6 +754,11 @@ case. Note that in this case, any previously-parsed JSON texts will be lost. +Example: Parse some JSON arrays/objects in a given string and return +them. + + my @objs = JSON::XS->new->incr_parse ("[5][7][1,2]"); + =item $lvalue_string = $json->incr_text This method returns the currently stored JSON fragment as an lvalue, that @@ -991,6 +997,11 @@ precision (in which case you might lose perfect roundtripping ability, but the JSON number will still be re-encoded as a JSON number). +Note that precision is not accuracy - binary floating point values cannot +represent most decimal fractions exactly, and when converting from and to +floating point, JSON::XS only guarantees precision up to but not including +the leats significant bit. + =item true, false These JSON atoms become C and C, @@ -1087,6 +1098,13 @@ if you need this capability (but don't forget to explain why it's needed :). +Note that numerical precision has the same meaning as under Perl (so +binary to decimal conversion follows the same rules as in Perl, which +can differ to other languages). Also, your perl interpreter might expose +extensions to the floating point numbers of your platform, such as +infinities or NaN's - these cannot be represented in JSON, and it is an +error to pass those in. + =back @@ -1240,7 +1258,7 @@ 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. +C<__proto__> property name for its own purposes. If that is a problem, you could parse try to filter the resulting JSON output for these property strings, e.g.: @@ -1304,10 +1322,10 @@ real compatibility for many I 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 +Addendum/2009: the YAML 1.2 spec is still incompatible 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 people and corrupting userdata is so much easier. =back @@ -1430,6 +1448,24 @@ (It might actually work, but you have been warned). +=head1 THE PERILS OF SETLOCALE + +Sometimes people avoid the Perl locale support and directly call the +system's setlocale function with C. + +This breaks both perl and modules such as JSON::XS, as stringification of +numbers no longer works correcly (e.g. C<$x = 0.1; print "$x"+1> might +print C<1>, and JSON::XS might output illegal JSON as JSON::XS relies on +perl to stringify numbers). + +The solution is simple: don't call C, or use it for only those +categories you need, such as C or C. + +If you need C, you should enable it only around the code that +actually needs it (avoiding stringification of numbers), and restore it +afterwards. + + =head1 BUGS While the goal of this module is to be correct, that unfortunately does