Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 1 | :mod:`uuid` --- UUID objects according to RFC 4122 |
| 2 | ================================================== |
| 3 | |
| 4 | .. module:: uuid |
| 5 | :synopsis: UUID objects (universally unique identifiers) according to RFC 4122 |
| 6 | .. moduleauthor:: Ka-Ping Yee <ping@zesty.ca> |
| 7 | .. sectionauthor:: George Yoshida <quiver@users.sourceforge.net> |
| 8 | |
| 9 | |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 10 | This module provides immutable :class:`UUID` objects (the :class:`UUID` class) |
| 11 | and the functions :func:`uuid1`, :func:`uuid3`, :func:`uuid4`, :func:`uuid5` for |
| 12 | generating version 1, 3, 4, and 5 UUIDs as specified in :rfc:`4122`. |
| 13 | |
| 14 | If all you want is a unique ID, you should probably call :func:`uuid1` or |
| 15 | :func:`uuid4`. Note that :func:`uuid1` may compromise privacy since it creates |
| 16 | a UUID containing the computer's network address. :func:`uuid4` creates a |
| 17 | random UUID. |
| 18 | |
| 19 | |
Georg Brandl | b044b2a | 2009-09-16 16:05:59 +0000 | [diff] [blame] | 20 | .. class:: UUID(hex=None, bytes=None, bytes_le=None, fields=None, int=None, version=None) |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 21 | |
| 22 | Create a UUID from either a string of 32 hexadecimal digits, a string of 16 |
| 23 | bytes as the *bytes* argument, a string of 16 bytes in little-endian order as |
| 24 | the *bytes_le* argument, a tuple of six integers (32-bit *time_low*, 16-bit |
| 25 | *time_mid*, 16-bit *time_hi_version*, 8-bit *clock_seq_hi_variant*, 8-bit |
| 26 | *clock_seq_low*, 48-bit *node*) as the *fields* argument, or a single 128-bit |
| 27 | integer as the *int* argument. When a string of hex digits is given, curly |
| 28 | braces, hyphens, and a URN prefix are all optional. For example, these |
| 29 | expressions all yield the same UUID:: |
| 30 | |
| 31 | UUID('{12345678-1234-5678-1234-567812345678}') |
| 32 | UUID('12345678123456781234567812345678') |
| 33 | UUID('urn:uuid:12345678-1234-5678-1234-567812345678') |
| 34 | UUID(bytes='\x12\x34\x56\x78'*4) |
| 35 | UUID(bytes_le='\x78\x56\x34\x12\x34\x12\x78\x56' + |
| 36 | '\x12\x34\x56\x78\x12\x34\x56\x78') |
| 37 | UUID(fields=(0x12345678, 0x1234, 0x5678, 0x12, 0x34, 0x567812345678)) |
| 38 | UUID(int=0x12345678123456781234567812345678) |
| 39 | |
| 40 | Exactly one of *hex*, *bytes*, *bytes_le*, *fields*, or *int* must be given. |
| 41 | The *version* argument is optional; if given, the resulting UUID will have its |
| 42 | variant and version number set according to RFC 4122, overriding bits in the |
| 43 | given *hex*, *bytes*, *bytes_le*, *fields*, or *int*. |
| 44 | |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 45 | |
Georg Brandl | b044b2a | 2009-09-16 16:05:59 +0000 | [diff] [blame] | 46 | :class:`UUID` instances have these read-only attributes: |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 47 | |
| 48 | .. attribute:: UUID.bytes |
| 49 | |
| 50 | The UUID as a 16-byte string (containing the six integer fields in big-endian |
| 51 | byte order). |
| 52 | |
| 53 | |
| 54 | .. attribute:: UUID.bytes_le |
| 55 | |
| 56 | The UUID as a 16-byte string (with *time_low*, *time_mid*, and *time_hi_version* |
| 57 | in little-endian byte order). |
| 58 | |
| 59 | |
| 60 | .. attribute:: UUID.fields |
| 61 | |
| 62 | A tuple of the six integer fields of the UUID, which are also available as six |
| 63 | individual attributes and two derived attributes: |
| 64 | |
| 65 | +------------------------------+-------------------------------+ |
| 66 | | Field | Meaning | |
| 67 | +==============================+===============================+ |
| 68 | | :attr:`time_low` | the first 32 bits of the UUID | |
| 69 | +------------------------------+-------------------------------+ |
| 70 | | :attr:`time_mid` | the next 16 bits of the UUID | |
| 71 | +------------------------------+-------------------------------+ |
| 72 | | :attr:`time_hi_version` | the next 16 bits of the UUID | |
| 73 | +------------------------------+-------------------------------+ |
| 74 | | :attr:`clock_seq_hi_variant` | the next 8 bits of the UUID | |
| 75 | +------------------------------+-------------------------------+ |
| 76 | | :attr:`clock_seq_low` | the next 8 bits of the UUID | |
| 77 | +------------------------------+-------------------------------+ |
| 78 | | :attr:`node` | the last 48 bits of the UUID | |
| 79 | +------------------------------+-------------------------------+ |
| 80 | | :attr:`time` | the 60-bit timestamp | |
| 81 | +------------------------------+-------------------------------+ |
| 82 | | :attr:`clock_seq` | the 14-bit sequence number | |
| 83 | +------------------------------+-------------------------------+ |
| 84 | |
| 85 | |
| 86 | .. attribute:: UUID.hex |
| 87 | |
| 88 | The UUID as a 32-character hexadecimal string. |
| 89 | |
| 90 | |
| 91 | .. attribute:: UUID.int |
| 92 | |
| 93 | The UUID as a 128-bit integer. |
| 94 | |
| 95 | |
| 96 | .. attribute:: UUID.urn |
| 97 | |
| 98 | The UUID as a URN as specified in RFC 4122. |
| 99 | |
| 100 | |
| 101 | .. attribute:: UUID.variant |
| 102 | |
| 103 | The UUID variant, which determines the internal layout of the UUID. This will be |
| 104 | one of the integer constants :const:`RESERVED_NCS`, :const:`RFC_4122`, |
| 105 | :const:`RESERVED_MICROSOFT`, or :const:`RESERVED_FUTURE`. |
| 106 | |
| 107 | |
| 108 | .. attribute:: UUID.version |
| 109 | |
| 110 | The UUID version number (1 through 5, meaningful only when the variant is |
| 111 | :const:`RFC_4122`). |
| 112 | |
| 113 | The :mod:`uuid` module defines the following functions: |
| 114 | |
| 115 | |
| 116 | .. function:: getnode() |
| 117 | |
| 118 | Get the hardware address as a 48-bit positive integer. The first time this |
| 119 | runs, it may launch a separate program, which could be quite slow. If all |
| 120 | attempts to obtain the hardware address fail, we choose a random 48-bit number |
| 121 | with its eighth bit set to 1 as recommended in RFC 4122. "Hardware address" |
| 122 | means the MAC address of a network interface, and on a machine with multiple |
| 123 | network interfaces the MAC address of any one of them may be returned. |
| 124 | |
| 125 | .. index:: single: getnode |
| 126 | |
| 127 | |
Georg Brandl | b044b2a | 2009-09-16 16:05:59 +0000 | [diff] [blame] | 128 | .. function:: uuid1(node=None, clock_seq=None) |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 129 | |
| 130 | Generate a UUID from a host ID, sequence number, and the current time. If *node* |
| 131 | is not given, :func:`getnode` is used to obtain the hardware address. If |
| 132 | *clock_seq* is given, it is used as the sequence number; otherwise a random |
| 133 | 14-bit sequence number is chosen. |
| 134 | |
| 135 | .. index:: single: uuid1 |
| 136 | |
| 137 | |
| 138 | .. function:: uuid3(namespace, name) |
| 139 | |
| 140 | Generate a UUID based on the MD5 hash of a namespace identifier (which is a |
| 141 | UUID) and a name (which is a string). |
| 142 | |
| 143 | .. index:: single: uuid3 |
| 144 | |
| 145 | |
| 146 | .. function:: uuid4() |
| 147 | |
| 148 | Generate a random UUID. |
| 149 | |
| 150 | .. index:: single: uuid4 |
| 151 | |
| 152 | |
| 153 | .. function:: uuid5(namespace, name) |
| 154 | |
| 155 | Generate a UUID based on the SHA-1 hash of a namespace identifier (which is a |
| 156 | UUID) and a name (which is a string). |
| 157 | |
| 158 | .. index:: single: uuid5 |
| 159 | |
| 160 | The :mod:`uuid` module defines the following namespace identifiers for use with |
| 161 | :func:`uuid3` or :func:`uuid5`. |
| 162 | |
| 163 | |
| 164 | .. data:: NAMESPACE_DNS |
| 165 | |
| 166 | When this namespace is specified, the *name* string is a fully-qualified domain |
| 167 | name. |
| 168 | |
| 169 | |
| 170 | .. data:: NAMESPACE_URL |
| 171 | |
| 172 | When this namespace is specified, the *name* string is a URL. |
| 173 | |
| 174 | |
| 175 | .. data:: NAMESPACE_OID |
| 176 | |
| 177 | When this namespace is specified, the *name* string is an ISO OID. |
| 178 | |
| 179 | |
| 180 | .. data:: NAMESPACE_X500 |
| 181 | |
| 182 | When this namespace is specified, the *name* string is an X.500 DN in DER or a |
| 183 | text output format. |
| 184 | |
| 185 | The :mod:`uuid` module defines the following constants for the possible values |
| 186 | of the :attr:`variant` attribute: |
| 187 | |
| 188 | |
| 189 | .. data:: RESERVED_NCS |
| 190 | |
| 191 | Reserved for NCS compatibility. |
| 192 | |
| 193 | |
| 194 | .. data:: RFC_4122 |
| 195 | |
| 196 | Specifies the UUID layout given in :rfc:`4122`. |
| 197 | |
| 198 | |
| 199 | .. data:: RESERVED_MICROSOFT |
| 200 | |
| 201 | Reserved for Microsoft compatibility. |
| 202 | |
| 203 | |
| 204 | .. data:: RESERVED_FUTURE |
| 205 | |
| 206 | Reserved for future definition. |
| 207 | |
| 208 | |
| 209 | .. seealso:: |
| 210 | |
| 211 | :rfc:`4122` - A Universally Unique IDentifier (UUID) URN Namespace |
| 212 | This specification defines a Uniform Resource Name namespace for UUIDs, the |
| 213 | internal format of UUIDs, and methods of generating UUIDs. |
| 214 | |
| 215 | |
| 216 | .. _uuid-example: |
| 217 | |
| 218 | Example |
| 219 | ------- |
| 220 | |
| 221 | Here are some examples of typical usage of the :mod:`uuid` module:: |
| 222 | |
| 223 | >>> import uuid |
| 224 | |
| 225 | # make a UUID based on the host ID and current time |
| 226 | >>> uuid.uuid1() |
| 227 | UUID('a8098c1a-f86e-11da-bd1a-00112444be1e') |
| 228 | |
| 229 | # make a UUID using an MD5 hash of a namespace UUID and a name |
| 230 | >>> uuid.uuid3(uuid.NAMESPACE_DNS, 'python.org') |
| 231 | UUID('6fa459ea-ee8a-3ca4-894e-db77e160355e') |
| 232 | |
| 233 | # make a random UUID |
| 234 | >>> uuid.uuid4() |
| 235 | UUID('16fd2706-8baf-433b-82eb-8c7fada847da') |
| 236 | |
| 237 | # make a UUID using a SHA-1 hash of a namespace UUID and a name |
| 238 | >>> uuid.uuid5(uuid.NAMESPACE_DNS, 'python.org') |
| 239 | UUID('886313e1-3b8a-5372-9b90-0c9aee199e5d') |
| 240 | |
| 241 | # make a UUID from a string of hex digits (braces and hyphens ignored) |
| 242 | >>> x = uuid.UUID('{00010203-0405-0607-0809-0a0b0c0d0e0f}') |
| 243 | |
| 244 | # convert a UUID to a string of hex digits in standard form |
| 245 | >>> str(x) |
| 246 | '00010203-0405-0607-0809-0a0b0c0d0e0f' |
| 247 | |
| 248 | # get the raw 16 bytes of the UUID |
| 249 | >>> x.bytes |
| 250 | '\x00\x01\x02\x03\x04\x05\x06\x07\x08\t\n\x0b\x0c\r\x0e\x0f' |
| 251 | |
| 252 | # make a UUID from a 16-byte string |
| 253 | >>> uuid.UUID(bytes=x.bytes) |
| 254 | UUID('00010203-0405-0607-0809-0a0b0c0d0e0f') |
| 255 | |