On Tue, Jul 24, 2018, 9:09 AM Chris Angelico <ros...@gmail.com> wrote:
> >>> x = Foo(cfg).user.profile > >>> x.food > > Remember, these lines could be a very long way apart. You could pass > 'x' to a function unrelated to the line of code that created it. And > 'x.food' still has to have the magic. You can't mandate that the call > to Coalesce be on the same line as the attribute access - Python > doesn't work that way. > > So your perfectly ordinary dot operator now does magic in addition to > normal attribute access. See why it's a dangerous thing? > Yes, of course. That's why I would recommend best practice is to unbox or otherwise use the conditional value as close to the magic code as feasible. Likewise, as I noted a little while ago, 'x.food' could equally well be a property that executed arbitrarily slow, magical, obscure, or even malicious operations. Equally, 'x + y' could do absolutely anything if we define .__add__() or .__radd__() methods. Everything in Python is magical in that sense, but we should deliberately keep the magic constrained to the amount needed. >
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