Number::Phone::Formatters - how to write custom formatters


How to write custom formatters for phone numbers.


Formatters are modules that live in the Number::Phone::Formatter::* namespace. Users only need to type the last bit of the name, without the leading Number::Phone::Formatter::, when calling the format_using method of Number::Phone.

The 'E123' formatter name is reserved and implemented by Number::Phone subclasses in their format() methods.

The 'FishAndChips' formatter name is reserved because I needed something guaranteed to not exist so I could test that it failed correctly.


There is one compulsory method, format that you must write. It will be called as a class method, with a number in E.123 international format as its first argument, looking something like '+CC NNN NNN NNN', and a Number::Phone object as its second argument. The gory details of what E.123 looks like are at but in summary, you'll get a string consisting of:

a plus sign
a 1, 2 or 3 digit country code
a mixture of digits and whitespace

You should return a string.


See Number::Phone::Formatter::Raw for an example that uses the string argument, and Number::Phone::Formatter::NationallyPreferredIntl for one that uses the object.


Copyright 2016 David Cantrell <>

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