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Revision 1.130 by root, Thu Mar 11 17:36:09 2010 UTC vs.
Revision 1.131 by root, Thu Mar 11 19:31:37 2010 UTC

… …
64so, and even documents what "correct" means. 64so, and even documents what "correct" means.
65 65
66=item * round-trip integrity 66=item * round-trip integrity
67 67
68When you serialise a perl data structure using only data types supported 68When you serialise a perl data structure using only data types supported
69by JSON, the deserialised data structure is identical on the Perl level. 69by JSON and Perl, the deserialised data structure is identical on the Perl
70(e.g. the string "2.0" doesn't suddenly become "2" just because it looks 70level. (e.g. the string "2.0" doesn't suddenly become "2" just because
71like a number). There minor I<are> exceptions to this, read the MAPPING 71it looks like a number). There I<are> minor exceptions to this, read the
72section below to learn about those. 72MAPPING section below to learn about those.
73 73
74=item * strict checking of JSON correctness 74=item * strict checking of JSON correctness
75 75
76There is no guessing, no generating of illegal JSON texts by default, 76There is no guessing, no generating of illegal JSON texts by default,
77and only JSON is accepted as input by default (the latter is a security 77and only JSON is accepted as input by default (the latter is a security
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994Numbers containing a fractional or exponential part will always be 994Numbers containing a fractional or exponential part will always be
995represented as numeric (floating point) values, possibly at a loss of 995represented as numeric (floating point) values, possibly at a loss of
996precision (in which case you might lose perfect roundtripping ability, but 996precision (in which case you might lose perfect roundtripping ability, but
997the JSON number will still be re-encoded as a JSON number). 997the JSON number will still be re-encoded as a JSON number).
998 998
999Note that precision is not accuracy - binary floating point values cannot
1000represent most decimal fractions exactly, and when converting from and to
1001floating point, JSON::XS only guarantees precision up to but not including
1002the leats significant bit.
1003
999=item true, false 1004=item true, false
1000 1005
1001These JSON atoms become C<JSON::XS::true> and C<JSON::XS::false>, 1006These JSON atoms become C<JSON::XS::true> and C<JSON::XS::false>,
1002respectively. They are overloaded to act almost exactly like the numbers 1007respectively. They are overloaded to act almost exactly like the numbers
1003C<1> and C<0>. You can check whether a scalar is a JSON boolean by using 1008C<1> and C<0>. You can check whether a scalar is a JSON boolean by using
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1089 $x *= 1; # same thing, the choice is yours. 1094 $x *= 1; # same thing, the choice is yours.
1090 1095
1091You can not currently force the type in other, less obscure, ways. Tell me 1096You can not currently force the type in other, less obscure, ways. Tell me
1092if you need this capability (but don't forget to explain why it's needed 1097if you need this capability (but don't forget to explain why it's needed
1093:). 1098:).
1099
1100Note that numerical precision has the same meaning as under Perl (so
1101binary to decimal conversion follows the same rules as in Perl, which
1102can differ to other languages). Also, your perl interpreter might expose
1103extensions to the floating point numbers of your platform, such as
1104infinities or NaN's - these cannot be represented in JSON, and it is an
1105error to pass those in.
1094 1106
1095=back 1107=back
1096 1108
1097 1109
1098=head1 ENCODING/CODESET FLAG NOTES 1110=head1 ENCODING/CODESET FLAG NOTES

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