I'm on my tablet, so cannot test at the moment. But is `str.upper()` REALLY
wrong about the Turkish dotless I (and dotted capital I) currently?!
That feels like a BPO needed if true.
On Wed, Dec 21, 2022, 1:04 AM Steven D'Aprano <st...@pearwood.info> wrote:
> On Wed, Dec 21, 2022 at 09:42:51AM +1100, Cameron Simpson wrote:
>
> > With str subtypes, the case that comes to my mind is mixing str
> > subtypes.
> [...]
> > So, yes, for many methods I might reasonably expect a new html(str). But
> > I can contrive situations where I'd want a plain str
>
> The key word there is *contrive*.
>
> Obviously there are methods that are expected to return plain old
> strings. If you have a html.extract_content() method which extracts the
> body of the html document as plain text, stripping out all markup, there
> is no point returning a html object and a str will do. But most methods
> will need to keep the markup, and so they will need to return a html
> object.
>
> HTML is probably not the greatest example for this issue, because I
> expect that a full-blown HTML string subclass would probably have to
> override nearly all methods, so in this *specific* case the status quo
> is probably fine in practice. The status quo mostly hurts *lightweight*
> subclasses:
>
> class TurkishString(str):
> def upper(self):
> return TurkishString(str.upper(self.replace('i', 'İ')))
> def lower(self):
> return TurkishString(str.lower(self.replace('I', 'ı')))
>
> That's fine so long as the *only* operations you do to a TurkishString
> is upper or lower. As soon as you do concatenation, substring
> replacement, stripping, joining, etc you get a regular string.
>
> So we've gone from a lightweight subclass that needs to override two
> methods, to a heavyweight subclass that needs to override 30+ methods.
>
> This is probably why we don't rely on subclassing that much. Easier to
> just write a top-level function and forget about subclassing.
>
>
> --
> Steve
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