1 2 :mod:`uuid` --- UUID objects according to RFC 4122 3 ================================================== 4 5 .. module:: uuid 6 :synopsis: UUID objects (universally unique identifiers) according to RFC 4122 7 .. moduleauthor:: Ka-Ping Yee <ping (a] zesty.ca> 8 .. sectionauthor:: George Yoshida <quiver (a] users.sourceforge.net> 9 10 11 .. versionadded:: 2.5 12 13 This module provides immutable :class:`UUID` objects (the :class:`UUID` class) 14 and the functions :func:`uuid1`, :func:`uuid3`, :func:`uuid4`, :func:`uuid5` for 15 generating version 1, 3, 4, and 5 UUIDs as specified in :rfc:`4122`. 16 17 If all you want is a unique ID, you should probably call :func:`uuid1` or 18 :func:`uuid4`. Note that :func:`uuid1` may compromise privacy since it creates 19 a UUID containing the computer's network address. :func:`uuid4` creates a 20 random UUID. 21 22 23 .. class:: UUID([hex[, bytes[, bytes_le[, fields[, int[, version]]]]]]) 24 25 Create a UUID from either a string of 32 hexadecimal digits, a string of 16 26 bytes in big-endian order as the *bytes* argument, a string of 16 bytes in 27 little-endian order as the *bytes_le* argument, a tuple of six integers 28 (32-bit *time_low*, 16-bit *time_mid*, 16-bit *time_hi_version*, 29 8-bit *clock_seq_hi_variant*, 8-bit *clock_seq_low*, 48-bit *node*) as the 30 *fields* argument, or a single 128-bit integer as the *int* argument. 31 When a string of hex digits is given, curly braces, hyphens, 32 and a URN prefix are all optional. For example, these 33 expressions all yield the same UUID:: 34 35 UUID('{12345678-1234-5678-1234-567812345678}') 36 UUID('12345678123456781234567812345678') 37 UUID('urn:uuid:12345678-1234-5678-1234-567812345678') 38 UUID(bytes='\x12\x34\x56\x78'*4) 39 UUID(bytes_le='\x78\x56\x34\x12\x34\x12\x78\x56' + 40 '\x12\x34\x56\x78\x12\x34\x56\x78') 41 UUID(fields=(0x12345678, 0x1234, 0x5678, 0x12, 0x34, 0x567812345678)) 42 UUID(int=0x12345678123456781234567812345678) 43 44 Exactly one of *hex*, *bytes*, *bytes_le*, *fields*, or *int* must be given. 45 The *version* argument is optional; if given, the resulting UUID will have its 46 variant and version number set according to RFC 4122, overriding bits in the 47 given *hex*, *bytes*, *bytes_le*, *fields*, or *int*. 48 49 :class:`UUID` instances have these read-only attributes: 50 51 52 .. attribute:: UUID.bytes 53 54 The UUID as a 16-byte string (containing the six integer fields in big-endian 55 byte order). 56 57 58 .. attribute:: UUID.bytes_le 59 60 The UUID as a 16-byte string (with *time_low*, *time_mid*, and *time_hi_version* 61 in little-endian byte order). 62 63 64 .. attribute:: UUID.fields 65 66 A tuple of the six integer fields of the UUID, which are also available as six 67 individual attributes and two derived attributes: 68 69 +------------------------------+-------------------------------+ 70 | Field | Meaning | 71 +==============================+===============================+ 72 | :attr:`time_low` | the first 32 bits of the UUID | 73 +------------------------------+-------------------------------+ 74 | :attr:`time_mid` | the next 16 bits of the UUID | 75 +------------------------------+-------------------------------+ 76 | :attr:`time_hi_version` | the next 16 bits of the UUID | 77 +------------------------------+-------------------------------+ 78 | :attr:`clock_seq_hi_variant` | the next 8 bits of the UUID | 79 +------------------------------+-------------------------------+ 80 | :attr:`clock_seq_low` | the next 8 bits of the UUID | 81 +------------------------------+-------------------------------+ 82 | :attr:`node` | the last 48 bits of the UUID | 83 +------------------------------+-------------------------------+ 84 | :attr:`time` | the 60-bit timestamp | 85 +------------------------------+-------------------------------+ 86 | :attr:`clock_seq` | the 14-bit sequence number | 87 +------------------------------+-------------------------------+ 88 89 90 .. attribute:: UUID.hex 91 92 The UUID as a 32-character hexadecimal string. 93 94 95 .. attribute:: UUID.int 96 97 The UUID as a 128-bit integer. 98 99 100 .. attribute:: UUID.urn 101 102 The UUID as a URN as specified in RFC 4122. 103 104 105 .. attribute:: UUID.variant 106 107 The UUID variant, which determines the internal layout of the UUID. This will be 108 one of the constants :const:`RESERVED_NCS`, :const:`RFC_4122`, 109 :const:`RESERVED_MICROSOFT`, or :const:`RESERVED_FUTURE`. 110 111 112 .. attribute:: UUID.version 113 114 The UUID version number (1 through 5, meaningful only when the variant is 115 :const:`RFC_4122`). 116 117 The :mod:`uuid` module defines the following functions: 118 119 120 .. function:: getnode() 121 122 Get the hardware address as a 48-bit positive integer. The first time this 123 runs, it may launch a separate program, which could be quite slow. If all 124 attempts to obtain the hardware address fail, we choose a random 48-bit number 125 with its eighth bit set to 1 as recommended in RFC 4122. "Hardware address" 126 means the MAC address of a network interface, and on a machine with multiple 127 network interfaces the MAC address of any one of them may be returned. 128 129 .. index:: single: getnode 130 131 132 .. function:: uuid1([node[, clock_seq]]) 133 134 Generate a UUID from a host ID, sequence number, and the current time. If *node* 135 is not given, :func:`getnode` is used to obtain the hardware address. If 136 *clock_seq* is given, it is used as the sequence number; otherwise a random 137 14-bit sequence number is chosen. 138 139 .. index:: single: uuid1 140 141 142 .. function:: uuid3(namespace, name) 143 144 Generate a UUID based on the MD5 hash of a namespace identifier (which is a 145 UUID) and a name (which is a string). 146 147 .. index:: single: uuid3 148 149 150 .. function:: uuid4() 151 152 Generate a random UUID. 153 154 .. index:: single: uuid4 155 156 157 .. function:: uuid5(namespace, name) 158 159 Generate a UUID based on the SHA-1 hash of a namespace identifier (which is a 160 UUID) and a name (which is a string). 161 162 .. index:: single: uuid5 163 164 The :mod:`uuid` module defines the following namespace identifiers for use with 165 :func:`uuid3` or :func:`uuid5`. 166 167 168 .. data:: NAMESPACE_DNS 169 170 When this namespace is specified, the *name* string is a fully-qualified domain 171 name. 172 173 174 .. data:: NAMESPACE_URL 175 176 When this namespace is specified, the *name* string is a URL. 177 178 179 .. data:: NAMESPACE_OID 180 181 When this namespace is specified, the *name* string is an ISO OID. 182 183 184 .. data:: NAMESPACE_X500 185 186 When this namespace is specified, the *name* string is an X.500 DN in DER or a 187 text output format. 188 189 The :mod:`uuid` module defines the following constants for the possible values 190 of the :attr:`variant` attribute: 191 192 193 .. data:: RESERVED_NCS 194 195 Reserved for NCS compatibility. 196 197 198 .. data:: RFC_4122 199 200 Specifies the UUID layout given in :rfc:`4122`. 201 202 203 .. data:: RESERVED_MICROSOFT 204 205 Reserved for Microsoft compatibility. 206 207 208 .. data:: RESERVED_FUTURE 209 210 Reserved for future definition. 211 212 213 .. seealso:: 214 215 :rfc:`4122` - A Universally Unique IDentifier (UUID) URN Namespace 216 This specification defines a Uniform Resource Name namespace for UUIDs, the 217 internal format of UUIDs, and methods of generating UUIDs. 218 219 220 .. _uuid-example: 221 222 Example 223 ------- 224 225 Here are some examples of typical usage of the :mod:`uuid` module:: 226 227 >>> import uuid 228 229 >>> # make a UUID based on the host ID and current time 230 >>> uuid.uuid1() 231 UUID('a8098c1a-f86e-11da-bd1a-00112444be1e') 232 233 >>> # make a UUID using an MD5 hash of a namespace UUID and a name 234 >>> uuid.uuid3(uuid.NAMESPACE_DNS, 'python.org') 235 UUID('6fa459ea-ee8a-3ca4-894e-db77e160355e') 236 237 >>> # make a random UUID 238 >>> uuid.uuid4() 239 UUID('16fd2706-8baf-433b-82eb-8c7fada847da') 240 241 >>> # make a UUID using a SHA-1 hash of a namespace UUID and a name 242 >>> uuid.uuid5(uuid.NAMESPACE_DNS, 'python.org') 243 UUID('886313e1-3b8a-5372-9b90-0c9aee199e5d') 244 245 >>> # make a UUID from a string of hex digits (braces and hyphens ignored) 246 >>> x = uuid.UUID('{00010203-0405-0607-0809-0a0b0c0d0e0f}') 247 248 >>> # convert a UUID to a string of hex digits in standard form 249 >>> str(x) 250 '00010203-0405-0607-0809-0a0b0c0d0e0f' 251 252 >>> # get the raw 16 bytes of the UUID 253 >>> x.bytes 254 '\x00\x01\x02\x03\x04\x05\x06\x07\x08\t\n\x0b\x0c\r\x0e\x0f' 255 256 >>> # make a UUID from a 16-byte string 257 >>> uuid.UUID(bytes=x.bytes) 258 UUID('00010203-0405-0607-0809-0a0b0c0d0e0f') 259 260
