[Python-Dev] Re: Should set objects maintain insertion order too?

2019-12-17 Thread Steven D'Aprano
On Sun, Dec 15, 2019 at 09:00:31PM -0800, Larry Hastings wrote: > I think we should decide the question "should set > objects maintain insertion order?" literally without any consideration > about performance implications. In your opening post: > I also want FAST lookup because I soemtimes rem

[Python-Dev] Re: Should set objects maintain insertion order too?

2019-12-17 Thread Larry Hastings
On 12/17/19 2:02 AM, Steven D'Aprano wrote: Without being facetious[1] if you don't care about performance, you don't need a set, you could use a list. Lists don't enforce uniqueness.  Apart from that a list would probably work fine for my needs; in my admittedly-modest workloads I would pr

[Python-Dev] Re: Should set objects maintain insertion order too?

2019-12-17 Thread Paul Moore
On Tue, 17 Dec 2019 at 11:13, Larry Hastings wrote: > I lack this strongly mathematical view of sets others have espoused; instead > I view them more like "dicts without values". I'm therefore disgruntled by > this inconsistency between what are I see as closely related data structures, > and

[Python-Dev] Re: Should set objects maintain insertion order too?

2019-12-17 Thread Ivan Levkivskyi
On Tue, 17 Dec 2019 at 11:48, Paul Moore wrote: > On Tue, 17 Dec 2019 at 11:13, Larry Hastings wrote: > > I lack this strongly mathematical view of sets others have espoused; > instead I view them more like "dicts without values". I'm therefore > disgruntled by this inconsistency between what a

[Python-Dev] Re: Should set objects maintain insertion order too?

2019-12-17 Thread Serhiy Storchaka
17.12.19 14:05, Ivan Levkivskyi пише: As a random data point, I often see the pattern where one needs to remove duplicates from the list while preserving the order of first appearance. This is for example needed to get stability in various type-checking situations (like union items, type variab

[Python-Dev] Re: Should set objects maintain insertion order too?

2019-12-17 Thread Tim Peters
... [Larry] >> One prominent Python core developer** wanted this feature for years, and I >> recall >> them saying something like: >> >> Guido says, "When a programmer iterates over a dictionary and they see the >> keys >> shift around when the dictionary changes, they learn something!" To that

[Python-Dev] Re: Should set objects maintain insertion order too?

2019-12-17 Thread Tim Peters
[Larry] > "I don't care about performance" is not because I'm aching for Python to > run my code slowly. It's because I'm 100% confident that the Python > community will lovingly optimize the implementation. I'm not ;-) > So when I have my language designer hat on, I really don't concern myself

[Python-Dev] sqlite3 module and thread-safe SQLite library

2019-12-17 Thread Kacvinsky, Tom
We ran into an issue where having the SQLite library built with -DSQLITE_THREADSAFE=0, but then the sqlite3 module (really, the _sqlite3.so0 crashing in threading code. So I have to ask if it is intended that the sqlite3 Python module always be built with a thread safe SQLite library. Thanks

[Python-Dev] Re: sqlite3 module and thread-safe SQLite library

2019-12-17 Thread Gregory P. Smith
On Tue, Dec 17, 2019 at 12:30 PM Kacvinsky, Tom wrote: > We ran into an issue where having the SQLite library built with > -DSQLITE_THREADSAFE=0, > but then the sqlite3 module (really, the _sqlite3.so0 crashing in > threading code. So I have > to ask if it is intended that the sqlite3 Python mo