Currently, the reprlib module [1] offers an "alternate repr()
implementation", and focuses mainly on guarding the length of the
returned string. I propose to broaden its scope slightly and make it
the place to add helper functions for writing __repr__(), and to add
one such function.
A dataclass automatically generates a __repr__ method (unless you ask
it not to).
@dataclasses.dataclass
class Spam:
quality: int
recipe: str
ham: complex
>>> Spam(75, "<censored>", 1j)
Spam(quality=75, recipe='<censored>', ham=1j)
For non-dataclass classes, it would be extremely helpful to have an
easy helper function available:
class Spam:
def __repr__(self):
return reprlib.kwargs(self, ["quality", "recipe", "ham"])
The implementation for this function would be very similar to what
dataclasses already do:
# in reprlib.py
def kwargs(obj, attrs):
attrs = [f"{a}={getattr(obj, a)!r}" for a in attrs]
return f"{obj.__class__.__qualname__}({", ".join(attrs)})"
A similar function for positional args would be equally easy.
Bikeshedding opportunity: Should it be legal to omit the attrs
parameter, and have it use __slots__ or fall back to dir(obj) ?
ChrisA
[1] https://docs.python.org/3/library/reprlib.html
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