Re: Configuring an object via a dictionary
On 17/03/24 12:06, Peter J. Holzer via Python-list wrote: On 2024-03-16 08:15:19 +, Barry via Python-list wrote: On 15 Mar 2024, at 19:51, Thomas Passin via Python-list wrote: I've always like writing using the "or" form and have never gotten bit I, on the other hand, had to fix a production problem that using “or” introducted. I avoid this idiom because it fails on falsy values. Perl has a // operator (pronounced "err"), which works like || (or), except that it tests whether the left side is defined (not None in Python terms) instead of truthy. This still isn't bulletproof but I've found it very handy. So, if starting from: def method( self, name=None, ): rather than: self.name = name if name else default_value ie self.name = name if name is True else default_value the more precise: self.name = name if name is not None or default_value or: self.name = default_value if name is None or name because "is" checks for identity, whereas "==" and True-thy encompass a range of possible alternate values? -- Regards, =dn -- https://mail.python.org/mailman/listinfo/python-list
Re: Configuring an object via a dictionary
On 2024-03-16 08:15:19 +, Barry via Python-list wrote: > > On 15 Mar 2024, at 19:51, Thomas Passin via Python-list > > wrote: > > I've always like writing using the "or" form and have never gotten bit > > I, on the other hand, had to fix a production problem that using “or” > introducted. > I avoid this idiom because it fails on falsy values. Perl has a // operator (pronounced "err"), which works like || (or), except that it tests whether the left side is defined (not None in Python terms) instead of truthy. This still isn't bulletproof but I've found it very handy. hp -- _ | Peter J. Holzer| Story must make more sense than reality. |_|_) || | | | h...@hjp.at |-- Charles Stross, "Creative writing __/ | http://www.hjp.at/ | challenge!" signature.asc Description: PGP signature -- https://mail.python.org/mailman/listinfo/python-list
Re: Configuring an object via a dictionary
On 16/03/24 21:15, Barry via Python-list wrote: On 15 Mar 2024, at 19:51, Thomas Passin via Python-list wrote: I've always like writing using the "or" form and have never gotten bit I, on the other hand, had to fix a production problem that using “or” introducted. I avoid this idiom because it fails on falsy values. As with any other facility, one has to understand ALL implications! It must be one of those intensely-frustrating errors to track-down, which is then oh-so-simple to fix! Are you able to list (real, if suitably anonymised) examples of where the truthy/falsy was inappropriate, please? -- Regards, =dn -- https://mail.python.org/mailman/listinfo/python-list
Re: Configuring an object via a dictionary
On 3/16/2024 8:12 AM, Roel Schroeven via Python-list wrote:
Barry via Python-list schreef op 16/03/2024 om 9:15:
> On 15 Mar 2024, at 19:51, Thomas Passin via Python-list
wrote:
> > I've always like writing using the "or" form and have never gotten
bit
I, on the other hand, had to fix a production problem that using “or”
introducted.
I avoid this idiom because it fails on falsy values.
Me too. It's just too fragile. When writing code you're going to need an
alternative for cases where "config.get('source_name') or default_value"
doesn't work correctly; much better to use that alternative for all cases.
Trying to remember when I've used it, that was probably on personal code
where I had a good idea what the values could be. Otherwise, I'm in
agreement.
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Re: Configuring an object via a dictionary
Barry via Python-list schreef op 16/03/2024 om 9:15:
> On 15 Mar 2024, at 19:51, Thomas Passin via Python-list
wrote:
>
> I've always like writing using the "or" form and have never gotten bit
I, on the other hand, had to fix a production problem that using “or”
introducted.
I avoid this idiom because it fails on falsy values.
Me too. It's just too fragile. When writing code you're going to need an
alternative for cases where "config.get('source_name') or default_value"
doesn't work correctly; much better to use that alternative for all cases.
--
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people living on it were unhappy for pretty much of the time. Many solutions
were suggested for this problem, but most of these were largely concerned with
the movement of small green pieces of paper, which was odd because on the whole
it wasn't the small green pieces of paper that were unhappy."
-- Douglas Adams
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Re: Configuring an object via a dictionary
> On 15 Mar 2024, at 19:51, Thomas Passin via Python-list > wrote: > > I've always like writing using the "or" form and have never gotten bit I, on the other hand, had to fix a production problem that using “or” introducted. I avoid this idiom because it fails on falsy values. Barry -- https://mail.python.org/mailman/listinfo/python-list
