On 2017-04-28 06:07, Nick Coghlan wrote:
…the root cause (writing imperative initialisers is still
part of the baseline recommendation for writing classes, and we don't
offer any supporting infrastructure for avoiding that directly in the
standard library)
For a *lot* of classes, what we want to be able to define is:
- a set of data fields
- a basic initialiser to set those fields by name
- a repr based on those fields (or a subset)
- equality comparisons based on those fields (or a subset)
- ordering comparisons based on those fields (or a subset)
- conversion to a JSON-friendly dict
- pickling support
- copying support
Nice! I've implemented a higher-level base class in a few projects that does
just this. Things like pickling and JSON I might want to put into "mixins", but
yes the majority of these would be nice to have implemented by default
"batteries included" style. I prefer a base class to decorators since they seem
to stay out of the way more:
class Vehicle(BaseObject, Picklable):
…
That still leaves the problem of how to define instance attributes concisely.
Perhaps a "defaults" member or marker, or one of the other examples in the
larger thread would do.
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