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From: Alf P. Steinbach on 4 Jun 2010 22:25
* Terry Reedy, on 05.06.2010 03:01:
> On 6/4/2010 8:01 PM, dmtr wrote:
>>> Why does it have to be a one-liner? Is the Enter key on your keyboard
>>> broken?
>>
>> Nah. I was simply looking for something natural and intuitive, like: m
>> = object(); m.a = 1;
>> Usually python is pretty good providing these natural and intuitive
>> solutions.
>
> As far as I can think of now, one cannot add attributes to *any*
> builtin-class instance, but can add attributes to any user class which
> does not have them disabled.
>
> >>> [].a = 3
> Traceback (most recent call last):
> File "<pyshell#15>", line 1, in <module>
> [].a = 3
> AttributeError: 'list' object has no attribute 'a'
> >>> class L(list): pass
>
> >>> i = L(); i; i.a = 3; i.a
> []
> 3
>
> Terry Jan Reedy

You can add attributes to functions.

I'm not sure, but I think it was you who once provided me with a reference to
the relevant PEP (thanks!), so I guess it just slipped your mind on a late
Friday night. :-)

See my earlier reply in this thread regarding that.

Regarding user defined classes, I gather that by "have them [attributes]
disabled" you're including the case of a class with slots?

There was an article recently in DDJ where the author seemed to be unaware of
this, but I'm not going to pay for the privilege of commenting on articles.


Cheers & hth.,

- Alf


PS: How come that when I post a blog entry proving mathematically that the
reader is really really smart, the number of views dropped like a stone? Huh.
But OK, it was just a late-night posting, I couldn't sleep so I posted a bit of
what I, late at night, thought was some funny or at least amusing philosophy...

--
blog at <url: http://alfps.wordpress.com>
From: Terry Reedy on 4 Jun 2010 23:13
On 6/4/2010 10:25 PM, Alf P. Steinbach wrote:

>> As far as I can think of now, one cannot add attributes to *any*
>> builtin-class instance, but can add attributes to any user class which
>> does not have them disabled.
>>
>> >>> [].a = 3
>> Traceback (most recent call last):
>> File "<pyshell#15>", line 1, in <module>
>> [].a = 3
>> AttributeError: 'list' object has no attribute 'a'
>> >>> class L(list): pass
>>
>> >>> i = L(); i; i.a = 3; i.a
>> []
>> 3
>>
>> Terry Jan Reedy
>
> You can add attributes to functions.
>
> I'm not sure, but I think it was you who once provided me with a
> reference to the relevant PEP (thanks!), so I guess it just slipped your
> mind on a late Friday night. :-)

Right on both counts. Function attributes are exceptions, and they were
added after I learned Python.

> Regarding user defined classes, I gather that by "have them [attributes]
> disabled" you're including the case of a class with slots?

Yes. or custom __setattr__ or something.

tjr



From: dmtr on 5 Jun 2010 22:07
Right.

>>> m = lambda:expando
>>> m.myattr = 1
>>> print m.myattr
1

-- Cheers, Dmitry
From: Aahz on 9 Jun 2010 22:31
In article <86beb1fe-36ec-4a89-b926-3bb227c09a6f(a)g39g2000pri.googlegroups.com>,
dmtr <dchichkov(a)gmail.com> wrote:
>
>>>> m = lambda:expando
>>>> m.myattr = 1
>>>> print m.myattr
>1

That's a *great* technique if your goal is to confuse people.
--
Aahz (aahz(a)pythoncraft.com) <*> http://www.pythoncraft.com/

"If you don't know what your program is supposed to do, you'd better not
start writing it." --Dijkstra
From: dmtr on 10 Jun 2010 21:25
On Jun 9, 7:31 pm, a...(a)pythoncraft.com (Aahz) wrote:
> dmtr  <dchich...(a)gmail.com> wrote:
>
> >>>> m = lambda:expando
> >>>> m.myattr = 1
> >>>> print m.myattr
> >1
>
> That's a *great* technique if your goal is to confuse people.
> --

Yeah. But it is kinda cute. Let's hope it won't get adapted
(adopted ;).

-- Dmitry
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