To void introducing a new built-in, we could do object.bag = SimpleNamespace
Le 27/07/2017 à 05:23, Mike Miller a écrit :
> Many times in the olden days when I needed a bag o' attributes to be
> passed around like a struct I'd make a dummy class, then instantiate
> it. (A lot harder than the java
On 27 July 2017 at 03:10, Steven D'Aprano wrote:
> On Thu, Jul 27, 2017 at 02:05:47AM +1000, Nick Coghlan wrote:
>> On 26 July 2017 at 11:05, Steven D'Aprano wrote:
>> > I don't see any way that this proposal can be anything by a subtle
>> > source of bugs. We have two *incompatible* requirements
On 27 July 2017 at 10:38, Steven D'Aprano wrote:
> On Thu, Jul 27, 2017 at 11:46:45AM +1200, Greg Ewing wrote:
>> Nick Coghlan wrote:
>> >The same applies to the ntuple concept, expect there it's the fact
>> >that it's a *tuple* that conveys the "order matters" expectation.
>>
>> That assumes ther
> To avoid introducing a new built-in, we could do object.bag =
SimpleNamespace
I am liking the idea of making SimpleNamespace more accessible, but maybe
we need to think a bit more about why one might want a tuple-with-names,
rather than just an easy way to create
an object-with-just-attributes.
Since we are talking about namedtuple and implementation, I just noticed:
In [22]: Point = namedtuple('Point', ['x', 'y'])
In [23]: p = Point(2,3)
In [24]: p.x = 5
---
AttributeErrorTraceback (most
This error message is the same for types with __slots__, and probably it is
indeed a bit too terse.
--
Ivan
On 27 July 2017 at 18:26, Chris Barker wrote:
> Since we are talking about namedtuple and implementation, I just noticed:
>
> In [22]: Point = namedtuple('Point', ['x', 'y'])
> In [23]:
On 7/26/17, Steven D'Aprano wrote:
[...]
> But this has a hidden landmine. If *any* module happens to use ntuple
> with the same field names as you, but in a different order, you will
> have mysterious bugs:
>
> x, y, z = spam
>
> You expect x=2, y=1, z=0 because that's the way you defined the f
On Fri, Jul 28, 2017 at 7:22 AM, Pavol Lisy wrote:
> On 7/26/17, Steven D'Aprano wrote:
>
> [...]
>
>> But this has a hidden landmine. If *any* module happens to use ntuple
>> with the same field names as you, but in a different order, you will
>> have mysterious bugs:
>>
>> x, y, z = spam
>>
>>
> But you'd need to decide whether you
want attributes (spam.x, spam.y) or items (spam["x"], spam["y"]). Both
would be useful at different times.
ChrisA
If something like this was ever added, it'd probably be items, then you
could implement a custom __unpack__ (or whatever name it'd be) method
On Fri, Jul 28, 2017 at 12:51 AM Chris Angelico wrote:
> On Fri, Jul 28, 2017 at 7:22 AM, Pavol Lisy wrote:
>
> > We have:
> > from module import x, y, z # where order is not important
> >
> > Could we have something similar with ntuple (SimpleNamespace, ...)?
> >
> > maybe:
> > for x, y, z fro
On Thu, Jul 27, 2017 at 2:50 PM, Chris Angelico wrote:
> On Fri, Jul 28, 2017 at 7:22 AM, Pavol Lisy wrote:
> > maybe:
> > for x, y, z from spam:
> > print(x, y, z)
>
> What you're asking for is something like JavaScript's "object
> destructuring" syntax.
Wasn't there just a big long discu
On Fri, Jul 28, 2017 at 9:31 AM, Chris Barker wrote:
>
>
> On Thu, Jul 27, 2017 at 2:50 PM, Chris Angelico wrote:
>>
>> On Fri, Jul 28, 2017 at 7:22 AM, Pavol Lisy wrote:
>> > maybe:
>> > for x, y, z from spam:
>> > print(x, y, z)
>>
>> What you're asking for is something like JavaScript's "
I've never liked that error message either:
>>> object().foo = 'bar'
Traceback (most recent call last):
File "", line 1, in
AttributeError: 'object' object has no attribute 'foo'
Should say the "object is immutable," not writable, or something of the sort.
On 2017-07-27 09:
On Fri, Jul 28, 2017 at 10:09 AM, Mike Miller wrote:
> I've never liked that error message either:
>
> >>> object().foo = 'bar'
> Traceback (most recent call last):
> File "", line 1, in
> AttributeError: 'object' object has no attribute 'foo'
>
>
> Should say the "object is imm
MRAB writes:
> But what about:
>
> >>> nt2 = ntuple(y=2, x=1)
>
> ? Does that mean that nt[0] == 2? Presumably, yes.
>
> Does nt == nt2?
>
> If it's False, then you've lost some of the advantage of using names
> instead of positions.
Sure. And if you use a dict, you've lost some
Ethan Furman writes:
> Tuples, named or otherwise, are positional first -- order matters.
> Specifying
>
> point = ntuple(y=2, x=-3)
>
> and having point[0] == 3 is going to be bizarre. This will be a
> source for horrible bugs.
I don't see how you get that?
Anyway, I expect that
On Thu, Jul 27, 2017 at 05:09:56PM -0700, Mike Miller wrote:
> I've never liked that error message either:
>
> >>> object().foo = 'bar'
> Traceback (most recent call last):
> File "", line 1, in
> AttributeError: 'object' object has no attribute 'foo'
>
>
> Should say the "obj
On 07/27/2017 06:24 PM, Stephen J. Turnbull wrote:
Ethan Furman writes:
Tuples, named or otherwise, are positional first -- order matters.
Specifying
point = ntuple(y=2, x=-3)
and having point[0] == 3 is going to be bizarre. This will be a
source for horrible bugs.
I don't see how yo
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