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A bug?

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  A bug? "umatrp@gmail.com" <trsexgl@gmail.com> - 2014-10-27 09:01 -0700
    Re: A bug? Wolfgang Maier <wolfgang.maier@biologie.uni-freiburg.de> - 2014-10-27 17:17 +0100
    Re: A bug? Ian Kelly <ian.g.kelly@gmail.com> - 2014-10-27 10:26 -0600
    Re: A bug? Denis McMahon <denismfmcmahon@gmail.com> - 2014-10-28 00:36 +0000
      Re: A bug? Rustom Mody <rustompmody@gmail.com> - 2014-10-27 18:12 -0700
        Re: A bug? Chris Angelico <rosuav@gmail.com> - 2014-10-28 12:25 +1100
          Re: A bug? Rustom Mody <rustompmody@gmail.com> - 2014-10-27 19:13 -0700
      Re: A bug? Joshua Landau <joshua@landau.ws> - 2014-10-28 01:29 +0000
        Re: A bug? Denis McMahon <denismfmcmahon@gmail.com> - 2014-10-29 02:17 +0000
          What for -- for?  (was A bug?) Rustom Mody <rustompmody@gmail.com> - 2014-10-28 20:22 -0700
            Re: What for -- for? (was A bug?) Zachary Ware <zachary.ware+pylist@gmail.com> - 2014-10-28 23:16 -0500
            Re: What for -- for? (was A bug?) Zachary Ware <zachary.ware+pylist@gmail.com> - 2014-10-28 23:23 -0500
              Re: What for -- for? (was A bug?) Rustom Mody <rustompmody@gmail.com> - 2014-10-28 21:40 -0700
                Re: What for -- for? (was A bug?) Zachary Ware <zachary.ware+pylist@gmail.com> - 2014-10-28 23:59 -0500
                  Re: What for -- for? (was A bug?) Rustom Mody <rustompmody@gmail.com> - 2014-10-28 22:15 -0700
                    Re: What for -- for? (was A bug?) Zachary Ware <zachary.ware+pylist@gmail.com> - 2014-10-29 00:39 -0500
                      Re: What for -- for? (was A bug?) Rustom Mody <rustompmody@gmail.com> - 2014-10-28 23:11 -0700
                        Re: What for -- for? (was A bug?) Zachary Ware <zachary.ware+pylist@gmail.com> - 2014-10-29 01:18 -0500
                          Finding way around ABCs (was What for -- for? (was A bug?)) Rustom Mody <rustompmody@gmail.com> - 2014-10-30 10:01 -0700
                            Re: Finding way around ABCs (was What for -- for? (was A bug?)) Ian Kelly <ian.g.kelly@gmail.com> - 2014-10-30 11:09 -0600
                              Re: Finding way around ABCs (was What for -- for? (was A bug?)) Rustom Mody <rustompmody@gmail.com> - 2014-10-30 10:16 -0700
                            Re: Finding way around ABCs (was What for -- for? (was A bug?)) Ian Kelly <ian.g.kelly@gmail.com> - 2014-10-30 11:11 -0600
            Re: What for -- for? (was A bug?) Ben Finney <ben+python@benfinney.id.au> - 2014-10-29 16:27 +1100
            Re: What for -- for? (was A bug?) Zachary Ware <zachary.ware+pylist@gmail.com> - 2014-10-29 00:42 -0500
              Re: What for -- for? (was A bug?) Rustom Mody <rustompmody@gmail.com> - 2014-10-28 22:57 -0700
            Re: What for -- for? (was A bug?) Ben Finney <ben+python@benfinney.id.au> - 2014-10-29 17:02 +1100
            Re: What for -- for? (was A bug?) Joshua Landau <joshua@landau.ws> - 2014-10-30 17:21 +0000
              Re: What for -- for? (was A bug?) Rustom Mody <rustompmody@gmail.com> - 2014-10-30 10:41 -0700

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#79960 — Re: Finding way around ABCs (was What for -- for? (was A bug?))

On Thursday, October 30, 2014 10:40:42 PM UTC+5:30, Ian wrote:
> On Thu, Oct 30, 2014 at 11:01 AM, Rustom Mody wrote:
> > On Wednesday, October 29, 2014 11:49:27 AM UTC+5:30, Zachary Ware wrote:
> >> On Wed, Oct 29, 2014 at 1:11 AM, Rustom Mody wrote:
> >> > On Wednesday, October 29, 2014 11:10:06 AM UTC+5:30, Zachary Ware wrote:
> >> >> Of course, that's 3 (progressively shorter) loops to get the names of
> >> >> the ABCs of a class compared to 1 (fairly short in the first place)
> >> >> loop for a map of relationships to all available ABCs, but optimizing
> >> >> such a toy as this would just be an exercise in futility :)
> >> >
> >> > Not so.
> >> >
> >> > The charm of introspection is that the introspection
> >> > itself can be introspected.
> >> > For that to be convincing there needs to be a good combo
> >> > of clarity and succinctness.  In particular why not reduce
> >> > the two functions to one?
> >> >
> >> > def get_abc_names(cls):
> >> >     return [abc.__name__ for abc in abcs if issubclass(cls,abc)]
> >>
> >> Well, it depends on what you actually want, the spec has been a bit fuzzy ;)
> >
> > Thanks for this much -- its helpful.
> > Regarding ABCs -- is there a central documentation for them:
> >
> > "What exactly is a sequence or iterable or etc protocol?"
> >
> > This information seems to be strewn all over the place but systematically.
> 
> Maybe the glossary?
> 
> https://docs.python.org/3/glossary.html

Ummm...

I was looking for something more reference-ish, ie
More prolix for ABCs
And not containing random bits of unconnected data like
- What is CPython
- What is EAFP

Maybe there's something in the bowels of the C(Python)-code?

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#79959 — Re: Finding way around ABCs (was What for -- for? (was A bug?))

On Thu, Oct 30, 2014 at 11:09 AM, Ian Kelly <ian.g.kelly@gmail.com> wrote:
> On Thu, Oct 30, 2014 at 11:01 AM, Rustom Mody <rustompmody@gmail.com> wrote:
>> On Wednesday, October 29, 2014 11:49:27 AM UTC+5:30, Zachary Ware wrote:
>>> On Wed, Oct 29, 2014 at 1:11 AM, Rustom Mody wrote:
>>> > On Wednesday, October 29, 2014 11:10:06 AM UTC+5:30, Zachary Ware wrote:
>>> >> Of course, that's 3 (progressively shorter) loops to get the names of
>>> >> the ABCs of a class compared to 1 (fairly short in the first place)
>>> >> loop for a map of relationships to all available ABCs, but optimizing
>>> >> such a toy as this would just be an exercise in futility :)
>>> >
>>> > Not so.
>>> >
>>> > The charm of introspection is that the introspection
>>> > itself can be introspected.
>>> > For that to be convincing there needs to be a good combo
>>> > of clarity and succinctness.  In particular why not reduce
>>> > the two functions to one?
>>> >
>>> > def get_abc_names(cls):
>>> >     return [abc.__name__ for abc in abcs if issubclass(cls,abc)]
>>>
>>> Well, it depends on what you actually want, the spec has been a bit fuzzy ;)
>>
>> Thanks for this much -- its helpful.
>> Regarding ABCs -- is there a central documentation for them:
>>
>> "What exactly is a sequence or iterable or etc protocol?"
>>
>> This information seems to be strewn all over the place but systematically.
>
> Maybe the glossary?

Also the documentation for the collections.abc and numbers modules:

https://docs.python.org/3/library/collections.abc.html
https://docs.python.org/3/library/numbers.html

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#79885 — Re: What for -- for? (was A bug?)

Zachary Ware <zachary.ware+pylist@gmail.com> writes:

> Of course, Gmail decided to wrap my long line for me. In case it's not
> obvious, that should be a single line.

Right, GMail is a poor choice for composing messages. You might get
better results installing a proper mail client, and communicating via
IMAP.

-- 
 \        “Pinky, are you pondering what I'm pondering?” “Wuh, I think |
  `\      so, Brain, but how will we get three pink flamingos into one |
_o__)                     pair of Capri pants?” —_Pinky and The Brain_ |
Ben Finney

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#79887 — Re: What for -- for? (was A bug?)

On Wed, Oct 29, 2014 at 12:27 AM, Ben Finney <ben+python@benfinney.id.au> wrote:
> Zachary Ware <zachary.ware+pylist@gmail.com> writes:
>
>> Of course, Gmail decided to wrap my long line for me. In case it's not
>> obvious, that should be a single line.
>
> Right, GMail is a poor choice for composing messages. You might get
> better results installing a proper mail client, and communicating via
> IMAP.

Noted, but it works fine 99% of the time for me.  I'm not really
interested in trying to get a proper mail client set up on 5 different
devices and 4 different platforms with settings shared between all
just to avoid inconvenient line-wrapping (that I can avoid just by
sticking to 80 column lines in the first place :).

Although if you have a suggestion for that kind of setup, I'm all ears.

-- 
Zach

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#79889 — Re: What for -- for? (was A bug?)

On Wednesday, October 29, 2014 11:14:14 AM UTC+5:30, Zachary Ware wrote:
> On Wed, Oct 29, 2014 at 12:27 AM, Ben Finney  wrote:
> > Zachary Ware writes:
> >
> >> Of course, Gmail decided to wrap my long line for me. In case it's not
> >> obvious, that should be a single line.
> >
> > Right, GMail is a poor choice for composing messages. You might get
> > better results installing a proper mail client, and communicating via
> > IMAP.
> 
> Noted, but it works fine 99% of the time for me.  I'm not really
> interested in trying to get a proper mail client set up on 5 different
> devices and 4 different platforms with settings shared between all
> just to avoid inconvenient line-wrapping (that I can avoid just by
> sticking to 80 column lines in the first place :).

I was going to say the same:
gmail is fine if you remember to press RET 

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#79892 — Re: What for -- for? (was A bug?)

Zachary Ware <zachary.ware+pylist@gmail.com> writes:

> […] just to avoid inconvenient line-wrapping (that I can avoid just by
> sticking to 80 column lines in the first place :).

That is a valid solution. If you have the discipline to stick to it,
congratulations :-)

-- 
 \        “If you ever drop your keys into a river of molten lava, let |
  `\                 'em go, because, man, they're gone.” —Jack Handey |
_o__)                                                                  |
Ben Finney

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#79961 — Re: What for -- for? (was A bug?)

On 29 October 2014 03:22, Rustom Mody <rustompmody@gmail.com> wrote:
> Yesterday I was trying to introduce python to some senior computer scientists.
>
> Tried showing a comprehension-based dir-walker vs a for-loop based one:
>
> def dw(p):
>    if isfile(p):
>       return [p]
>    else:
>       return [p] + [c for f in listdir(p) for c in dw(p+'/'+f)]
>
...
>
> Comment to me : "Well this is neat and compact, but it does not add
> anything fundamental (over usual index based for-loops)"
>
> I tried to say that 'for' over general sequences is quite different
> and significantly more powerful than C/Pascal for over indexes +
> explicit indexing.

If you really want to show the generality of iteration, I suggest you
start with iterators:

    def walk(path):
        yield path

        if isdir(path):
            for name in iterdir(path):
                for file in walk(path + "/" + name):
                    yield file

This is fundementally inexpressable with indexes. It also lends itself
to expressing delegation (eg. "yield from walk(path + "/" + name)").

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#79962 — Re: What for -- for? (was A bug?)

On Thursday, October 30, 2014 10:53:13 PM UTC+5:30, Joshua Landau wrote:
> On 29 October 2014 03:22, Rustom Mody  wrote:
> > Yesterday I was trying to introduce python to some senior computer scientists.
> >
> > Tried showing a comprehension-based dir-walker vs a for-loop based one:
> >
> > def dw(p):
> >    if isfile(p):
> >       return [p]
> >    else:
> >       return [p] + [c for f in listdir(p) for c in dw(p+'/'+f)]
> >
> ...
> >
> > Comment to me : "Well this is neat and compact, but it does not add
> > anything fundamental (over usual index based for-loops)"
> >
> > I tried to say that 'for' over general sequences is quite different
> > and significantly more powerful than C/Pascal for over indexes +
> > explicit indexing.
> 
> If you really want to show the generality of iteration, I suggest you
> start with iterators:
> 
>     def walk(path):
>         yield path
> 
>         if isdir(path):
>             for name in iterdir(path):
>                 for file in walk(path + "/" + name):
>                     yield file

heh!
That was my next version -- almost word-for-word
[Not on that laptop now; will check later]

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