On Sat, Oct 30, 2021 at 10:51:42PM -0700, [email protected]
wrote:
> I still see anything more complicated than a constant or an extremely
> simple expression (len(a)? well, ok, maybe; (len(a) if is_prime((len(a))
> else next_larger_prime(len(a)))? don't push it) as no longer being a
> default, but something more serious, but I don't have a better name for
> it than "computation" or "part of the function" or even "business logic"
> or "a bad API."
There is no benefit to using an actual constant as a late-bound default.
If the value is constant, then why delay evaluation? You're going to get
the same constant one way or another. So linters should flag misuse
like:
func(@arg=0)
List and dict displays ("literals") like [] and {} are a different
story, but they aren't constants.
I agree that extremely complex expressions fall under the category of
"Don't Do That". But that's a code review and/or linter problem to
solve.
Most uses of late-binding defaults are going to be short and simple,
such as:
* an empty list or dict display;
* call a function;
* access an attribute of self;
* len of another argument.
Right now, defaults can be set to arbitrarily complex expressions. When
is the last time you saw a default that was uncomfortably complex?
--
Steve
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