How can I add custom formatters to my classes similar to datetime?

Question

With datetime objects, you can use .format in a special way:

from datetime import datetime
'{:%Y-%m-%d %H:%M}'.format(datetime(1990, 4, 28, 22, 30))

Those are the usual formatters for datetime objects.

Can I give any class such custom ways to format them? How?

The dupe target refers to string formatting only. This question seems to be for an object of arbitrary class, although the title makes it sound like it's about `datetime`. I'd say this isn't a dupe, but the title should be edited. — C8H10N4O2, Aug 09 '17 at 19:07
@C8H10N4O2 https://stackoverflow.com/a/19864463/846892. `__format__` is decently known, you could find more dupes easily, for example: https://stackoverflow.com/q/28904602/846892 — Ashwini Chaudhary, Aug 09 '17 at 19:16

score 2 · Accepted Answer · answered Aug 09 '17 at 19:03

2

Just found the answer on https://pyformat.info/:

Yes

class HAL9000(object):

    def __format__(self, format):
        if (format == 'open-the-pod-bay-doors'):
            return "I'm afraid I can't do that."
        return 'HAL 9000'

answered Aug 09 '17 at 19:03

Martin Thoma

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How can I add custom formatters to my classes similar to datetime?

1 Answers1