`class SerialNumber(FancyStrMixin): (source)`

Constructor: `SerialNumber(number, serialBits)`

An RFC1982 Serial Number.

This class implements RFC1982 DNS Serial Number Arithmetic.

SNA is used in DNS and specifically in DNSSEC as defined in RFC4034 in the DNSSEC Signature Expiration and Inception Fields.

See Also | |

https://tools.ietf.org/html/rfc1982 | |

https://tools.ietf.org/html/rfc4034 |

Class Method | `from` |
Create an `SerialNumber` instance from a date string in format 'YYYYMMDDHHMMSS' described in RFC4034 3.2. |

Method | `__add__` |
Allow addition with another `SerialNumber` instance. |

Method | `__eq__` |
Allow rich equality comparison with another `SerialNumber` instance. |

Method | `__ge__` |
Allow greater than or equal comparison with another `SerialNumber` instance. |

Method | `__gt__` |
Allow greater than comparison with another `SerialNumber` instance. |

Method | `__hash__` |
Allow `SerialNumber` instances to be hashed for use as `dict` keys. |

Method | `__init__` |
Construct an `SerialNumber` instance. |

Method | `__int__` |
No summary |

Method | `__le__` |
Allow less than or equal comparison with another `SerialNumber` instance. |

Method | `__lt__` |
Allow less than comparison with another `SerialNumber` instance. |

Method | `__str__` |
Return a string representation of this `SerialNumber` instance. |

Method | `to` |
Calculate a date by treating the current `SerialNumber` value as a UNIX timestamp and return a date string in the format described in RFC4034 3.2. |

Class Variable | `show` |
Undocumented |

Method | `_convert` |
Check that a foreign object is suitable for use in the comparison or arithmetic magic methods of this `SerialNumber` instance. Raise `TypeError` if not. |

Instance Variable | `_half` |
Half _modulo. If another `SerialNumber` value is larger than this, it would lead to a wrapped value which is larger than the first and comparisons are therefore ambiguous. |

Instance Variable | `_max` |
Half _modulo plus 1. If another `SerialNumber` value is larger than this, it would lead to a wrapped value which is larger than the first. Comparisons with the original value would therefore be ambiguous. |

Instance Variable | `_modulo` |
The value at which wrapping will occur. |

Instance Variable | `_number` |
See number of `__init__` . |

Instance Variable | `_serial` |
See serialBits of `__init__` . |

Create an `SerialNumber`

instance from a date string in format 'YYYYMMDDHHMMSS' described in RFC4034 3.2.

The `SerialNumber`

instance stores the date as a 32bit UNIX timestamp.

Parameters | |

utc`unicode` | A UTC date/time string of format YYMMDDhhmmss which will be converted to seconds since the UNIX epoch. |

Returns | |

An `SerialNumber` instance containing the supplied date as a 32bit UNIX timestamp. | |

See Also | |

https://tools.ietf.org/html/rfc4034#section-3.1.5 |

Allow *addition* with another `SerialNumber`

instance.

Serial numbers may be incremented by the addition of a positive integer n, where n is taken from the range of integers [0 .. (2^(SERIAL_BITS - 1) - 1)]. For a sequence number s, the result of such an addition, s', is defined as

s' = (s + n) modulo (2 ^ SERIAL_BITS)

where the addition and modulus operations here act upon values that are non-negative values of unbounded size in the usual ways of integer arithmetic.

Addition of a value outside the range [0 .. (2^(SERIAL_BITS - 1) - 1)] is undefined.

Raises | |

`ArithmeticError` | If other is more than _maxAdd ie more than half the maximum value of this serial number. |

See Also | |

http://tools.ietf.org/html/rfc1982#section-3.1 |

Construct an `SerialNumber`

instance.

Parameters | |

number:`int` | An `int` which will be stored as the modulo number % 2 ^ serialBits |

serial`int` | The size of the serial number space. The power of two which results in one larger than the largest integer corresponding to a serial number value. |

Calculate a date by treating the current `SerialNumber`

value as a UNIX timestamp and return a date string in the format described in RFC4034 3.2.

Returns | |

The date string. |

Check that a foreign object is suitable for use in the comparison or arithmetic magic methods of this `SerialNumber`

instance. Raise `TypeError`

if not.

Parameters | |

other:`object` | The foreign `object` to be checked. |

Returns | |

`SerialNumber` | other after compatibility checks and possible coercion. |

Raises | |

`TypeError` | If other is not compatible. |

Half `_modulo`. If another `SerialNumber`

value is larger than this, it would lead to a wrapped value which is larger than the first and comparisons are therefore ambiguous.

Half `_modulo` plus 1. If another `SerialNumber`

value is larger than this, it would lead to a wrapped value which is larger than the first. Comparisons with the original value would therefore be ambiguous.