> As Matthew points out, you could use numpy.array. Or code your own > class, by providing __add__ and __iadd__ methods. > > >>> import numpy > >>> a = numpy.array([1, 2]) > >>> b = numpy.array([3, 4]) > >>> a + b > array([4, 6]) > >>> a += b > >>> a > array([4, 6])
I could, but I don't think that justifies not having this functionality in python standard. From the language experience perspective, numpy is often a pain to install on most systems. If I'm designing card games and I just want to run a quick monte carlo simulation, the experience should be as smooth as possible. This is something I think most students will expect while learning python, especially if they're implementing algorithms. On Mon, Aug 27, 2018 at 4:24 AM <python-ideas-requ...@python.org> wrote: > Send Python-ideas mailing list submissions to > python-ideas@python.org > > To subscribe or unsubscribe via the World Wide Web, visit > https://mail.python.org/mailman/listinfo/python-ideas > or, via email, send a message with subject or body 'help' to > python-ideas-requ...@python.org > > You can reach the person managing the list at > python-ideas-ow...@python.org > > When replying, please edit your Subject line so it is more specific > than "Re: Contents of Python-ideas digest..." > > > Today's Topics: > > 1. Re: Unpacking iterables for augmented assignment (Matthew Einhorn) > 2. Re: Unpacking iterables for augmented assignment (Jonathan Fine) > 3. Re: Pre-conditions and post-conditions (Jacco van Dorp) > 4. Re: Pre-conditions and post-conditions (Ivan Levkivskyi) > > > ---------------------------------------------------------------------- > > Message: 1 > Date: Mon, 27 Aug 2018 01:29:14 -0400 > From: Matthew Einhorn <moiein2...@gmail.com> > To: python-ideas@python.org > Subject: Re: [Python-ideas] Unpacking iterables for augmented > assignment > Message-ID: > <CALCauYeAjPWek5L=BU-= > ymm-fnyw3bza2hjqsgmdgtrvbua...@mail.gmail.com> > Content-Type: text/plain; charset="utf-8" > > On Sun, Aug 26, 2018, 9:24 PM James Lu <jam...@gmail.com> wrote: > > > Hi Johnathan > > > > I echo your points. Indeed, the PEP referenced to refers to a "tuple > > expression" in the grammatical and not the programmatic sense. > > > > Finally, here's something that surprised me a little bit > > > > >>> x = [1, 2]; id(x) > > 140161160364616 > > >>> x += [3, 4]; id(x) > > 140161160364616 > > > > >>> x = (1, 2); id(x) > > 140161159928520 > > >>> x += (3, 4); id(x) > > 140161225906440 > > > > Notice that '+=' creates uses the same object when the object is > > a > > list, but creates a new object. This raises the question: Why and > > how > > does Python behave in this way? > > > > It's because lists are mutable are tuples are immutable. > > There's a dunder iadd method and a dunder add method. > > iadd magic methods, operating on the left hand side, return None and > > modify the object in-place. add magic methods return the result and > > don't modify the object it's called on. > > iadd is mutable add, whereas add is "return a copy with the result > > added" > > > > >>> tuple.__iadd__ > > Traceback (most recent call last): > > File "<stdin>", line 1, in <module> > > AttributeError: type object 'tuple' has no attribute '__iadd__' > > type object 'tuple' has no attribute '__iadd__' > > >>> tuple.__add__ > > <slot wrapper '__add__' of 'tuple' objects> > > >>> list.__iadd__ > > <slot wrapper '__iadd__' of 'list' objects> > > >>> list.__add__ > > <slot wrapper '__add__' of 'list' objects> > > > > > > tuple1 = tuple1.__add__(tuple2) > > > > list1.__iadd__(list2) > > > > > Does it IN PRACTICE bring sufficient benefits to users? > > > > I found myself needing this when I was writing a monte-carlo > > simulation in python that required incrementing a tallying counter > > from a subroutine. > > > > > Wouldn't a numpy array be very suited for this kind of task? > > > > -------------- next part -------------- > An HTML attachment was scrubbed... > URL: < > http://mail.python.org/pipermail/python-ideas/attachments/20180827/a1c698af/attachment-0001.html > > > > ------------------------------ > > Message: 2 > Date: Mon, 27 Aug 2018 07:25:00 +0100 > From: Jonathan Fine <jfine2...@gmail.com> > To: python-ideas <python-ideas@python.org> > Subject: Re: [Python-ideas] Unpacking iterables for augmented > assignment > Message-ID: > <CALD= > yf9b7erxanbvbxz2ybjr4zleyv1tphv7+u3ebo2sw08...@mail.gmail.com> > Content-Type: text/plain; charset="UTF-8" > > James has suggested that Python be enhanced so that > >>> a, b += c, d > is a short-hand for > >>> a += c > >>> b += d > > Myself, James and Matthew wrote > > >> > Does it IN PRACTICE bring sufficient benefits to users? > > >> I found myself needing this when I was writing a monte-carlo > >> simulation in python that required incrementing a tallying counter > >> from a subroutine. > > > Wouldn't a numpy array be very suited for this kind of task? > > Perhaps, James, you might like to refactor your code so that > >>> tally += simulation(args) > does what you want. > > As Matthew points out, you could use numpy.array. Or code your own > class, by providing __add__ and __iadd__ methods. > > >>> import numpy > >>> a = numpy.array([1, 2]) > >>> b = numpy.array([3, 4]) > >>> a + b > array([4, 6]) > >>> a += b > >>> a > array([4, 6]) > > -- > Jonathan > > > ------------------------------ > > Message: 3 > Date: Mon, 27 Aug 2018 09:04:21 +0200 > From: Jacco van Dorp <j.van.d...@deonet.nl> > To: python-ideas <python-ideas@python.org> > Subject: Re: [Python-ideas] Pre-conditions and post-conditions > Message-ID: > <CAKnNRP= > kzlvch+6mk+imzvncdf412qkpo4fojmetlf2euu9...@mail.gmail.com> > Content-Type: text/plain; charset="utf-8" > > Total noob speaking here, but.... > > Those contracts are mostly important during development right ? Slowdown > isn't that much of an issue during development. So you could make a debug > mode that enforces the contracts, and a production mode that code users can > use during production to stop the slowdown - in this case, your decorators > can return their functions/classes unaltered. If they do end up with > problems, you can always ask them to run the same inputs with debug mode on > to see where it goes wrong. > > For the rest, i'm totally new to design by contract. I do get the draw of > it, but im not sure if I'd ever really use it. I tend to solve my problems > with a royal sprinkling of logger.debug(f"{val_i_need_to_check}"). > -------------- next part -------------- > An HTML attachment was scrubbed... > URL: < > http://mail.python.org/pipermail/python-ideas/attachments/20180827/e59ffdd2/attachment-0001.html > > > > ------------------------------ > > Message: 4 > Date: Mon, 27 Aug 2018 09:24:20 +0100 > From: Ivan Levkivskyi <levkivs...@gmail.com> > To: j.van.d...@deonet.nl > Cc: python-ideas <python-ideas@python.org> > Subject: Re: [Python-ideas] Pre-conditions and post-conditions > Message-ID: > <CAOMjWk=ZrQSFBYKWGgne+2RgF8KvfJrRSt3qw= > vne9yhgfy...@mail.gmail.com> > Content-Type: text/plain; charset="utf-8" > > TBH, I think one of the main points of design by contract is that contracts > are verified statically. > For runtime contract checking I would rather recommend hypothesis library > (or similar). > > -- > Ivan > > > > On Mon, 27 Aug 2018 at 08:05, Jacco van Dorp <j.van.d...@deonet.nl> wrote: > > > Total noob speaking here, but.... > > > > Those contracts are mostly important during development right ? Slowdown > > isn't that much of an issue during development. So you could make a debug > > mode that enforces the contracts, and a production mode that code users > can > > use during production to stop the slowdown - in this case, your > decorators > > can return their functions/classes unaltered. If they do end up with > > problems, you can always ask them to run the same inputs with debug mode > on > > to see where it goes wrong. > > > > For the rest, i'm totally new to design by contract. I do get the draw of > > it, but im not sure if I'd ever really use it. I tend to solve my > problems > > with a royal sprinkling of logger.debug(f"{val_i_need_to_check}"). > > _______________________________________________ > > Python-ideas mailing list > > Python-ideas@python.org > > https://mail.python.org/mailman/listinfo/python-ideas > > Code of Conduct: http://python.org/psf/codeofconduct/ > > > -------------- next part -------------- > An HTML attachment was scrubbed... > URL: < > http://mail.python.org/pipermail/python-ideas/attachments/20180827/5cdeae6c/attachment.html > > > > ------------------------------ > > Subject: Digest Footer > > _______________________________________________ > Python-ideas mailing list > Python-ideas@python.org > https://mail.python.org/mailman/listinfo/python-ideas > > > ------------------------------ > > End of Python-ideas Digest, Vol 141, Issue 145 > ********************************************** >
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