How to detect that a function argument is the default one

[Jussi Piitulainen]

Jean-Michel Pichavant writes:

> If you like one-liners,
> 
> def __init__(self, center=(0,0), radius=10, mass=None):
>     self.center = center
>     self.radius = radius
>     self.mass = (mass is None and radius**2) or mass

That's not a one-liner. That's a one-liner:

def __init__(self, center=(0,0), radius=10, mass=None): self.center = center ; self.radius = radius ; self.mass = (mass is None and radius**2) or mass

And as others point out, you could highlight the number of
sub-expressions better by using an actual three-place expression.
(Why _that_ is considered so salient, I don't know. But it is.)

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