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| Started by | Dennis Lee Bieber <wlfraed@ix.netcom.com> |
|---|---|
| First post | 2014-12-02 23:05 -0500 |
| Last post | 2014-12-02 23:05 -0500 |
| Articles | 1 — 1 participant |
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Re: Proposed new conditional operator: "or else" Dennis Lee Bieber <wlfraed@ix.netcom.com> - 2014-12-02 23:05 -0500
| From | Dennis Lee Bieber <wlfraed@ix.netcom.com> |
|---|---|
| Date | 2014-12-02 23:05 -0500 |
| Subject | Re: Proposed new conditional operator: "or else" |
| Message-ID | <mailman.16511.1417579537.18130.python-list@python.org> |
On Tue, 2 Dec 2014 12:18:36 -0500, Roy Smith <roy@panix.com> declaimed the
following:
>In the process of refactoring some code, I serendipitously created what I think is an essential new bit of Python syntax. The “or else” statement. I ended up with:
>
> sites_string = args.sites or else self.config['sites']
>
>which, of course, is a syntax error today, but it got me thinking what we could do with an “or else” construct. Perhaps an alternative to assertions? Wouldn’t it be neat to write:
Well -- currently, since Python does short circuit conditionals, ALL
"or" conditions are the equivalent of "or else" (which is an Ada construct:
A or B evaluates both sides, A or else B only evaluates B if A is false.
The converse operation in Ada is and then: A and then B)
>
> foo == 42 or else
>
Has a PERL stink to it... like: foo == 42 or die
--
Wulfraed Dennis Lee Bieber AF6VN
wlfraed@ix.netcom.com HTTP://wlfraed.home.netcom.com/
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