On Tue, 5 May 2020, 18:24 Steven D'Aprano, <st...@pearwood.info> wrote:
> On Tue, May 05, 2020 at 05:26:02PM +0100, Henk-Jaap Wagenaar wrote:
>
> > This is a straw man in regards to backwards compatibility. This
> particular
> > (sub)thread is about whether if this zip-is-strict either as a separate
> > name or a Boolean flag or some other flag of zip should be a built-in or
> be
> > in e.g. itertools.
>
> Please don't misuse "strawman" in that fashion. A strawman argument is a
> logical fallacy where you attack a weaker position your opponent didn't
> make in order to make your own position stronger. That's not what Chris
> did, and frankly accusing him of strawmanning is a form of "poisoning
> the well".
> What Chris did was to propose a counterfactual to express his opinion on
> this proposal. To paraphrase:
>
> "If this were true (we were designing zip from scratch for the first
> time) then I would agree with the proposal, but since we aren't, I
> disagree because of these reasons."
>
> That is a perfectly legitimate position to take.
>
I agree on the face of it (in regards to strawmanning and your
paraphrasing), except I wasn't disagreeing with anything you've gone into
the detail above, but I disagreed with one of the reasons listed and
thought it was strawmanning, namely the "the backward compatibility break
large" (see further down, why).
>
> "If we weren't in lockdown, I would take you out for dinner at a
> restaurant, but since we are in quarantine, I don't think we
> should go out."
>
> Personally, I don't think Chris' backwards-compatibility argument is
> strong. Technically adding a new keyword argument to a function is
> backwards-incompatible, but we normally exclude that sort of change. Who
> writes this?
>
> # This behaviour will be changed by the proposed new parameter.
> zip('', strict=1) # Raise a type error.
>
> So I think the *backwards incompatibility* argument is weak in that
> regard. But maybe Chris has got a different perspective on this that I
> haven't thought of.
>
>
I cannot interpret that as a "large" break as Chris says, so I must assume
he meant something else (changing the default is my assumption) unless
somebody (Chris or otherwise) can tell me why adding a keyword argument
would be a large incompatible change?
>
> [Chris]
> > > Should they? I'm not sure how well-supported this actually is. If you
> > > hand-craft an AST and then compile it, is it supposed to catch every
> > > possible malformation?
>
> I would expect that the ast library should accept anything which could
> come from legal Python, and nothing that doesn't.
>
>
> --
> Steven
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