Mprn

A UK gas supply's meter point reference number (Xoserve), 6 to 10 digits: 1234567.

Other with a published standard; not ordered; personal data (contact); since Jadpo 0.1.0.

Make one

Build one from its text, Mprn("1234567"), which checks it: text that isn't one breaks format.

text.parse(raw, as: Mprn) reads one from its text; text that isn't one at all fails malformed, such as 12345, 12345678901 or 12 34567.

Text, JSON and storage

text.from writes its canonical text, the one form text.parse reads back. JSON sends its canonical text as a string.

It is stored in one column named for the field, of type text. 9876543210 is stored as '9876543210'.

Shown to people

text.format(value, locale:) shows it to people in their locale.

With locale: Locale.en_gb:

Operations

It has the contract's own operations: text.parse, text.from, text.format, json.read, json.write and ==. It isn't ordered, so < and sorting don't take it. Every standard type meets one contract says how they work.