__str__ vs. __repr__
tim_one at email.msn.com
Tue Nov 2 06:05:30 CET 1999
[Randall Hopper gives an example]
> class c:
> def __str__(self): return 'foo'
> def __repr__(self): return 'bar'
> >>> str(c())
> >>> str([c(), c(), c()])
> '[bar, bar, bar]'
[which Gordon McMillan explains, adding]
> Sick enough, but not convoluted enough, to be a Tim-ism...
It's too convoluted for my tastes! The real illness is that lists (and
dicts, and tuples) don't pass str-vs-repr'ness *down*. That is, even though
the example explicitly asks for str of a list, the list object asks for the
repr of its elements. That's convoluted: if (as happens to be true) str is
meant to give a friendly string, why do the builtin container types ask
their containees to produce unfriendly strings regardless? For that matter,
why is repr implied at an interactive prompt given a raw expression? Seems
that friendly strings would be more appropriate there. And why is there a
shorthand (`x`) for repr(x) but not for str(x)?
These are Great Mysteries debated even among the Ancient Ones. If the
scheme didn't already exist, I don't think we'd have much luck arguing for
its adoption <wink>.
3/4ths-of-one-idea-plus-1/4th-of-another-adds-up-to-2/3rds-ly y'rs - tim
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