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Dynamically reference member of array

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  Dynamically reference member of array Ben Collier <bmcollier@gmail.com> - 2014-03-26 04:43 -0700
    Dynamically reference variable in object Ben Collier <bmcollier@gmail.com> - 2014-03-26 04:44 -0700
      Re: Dynamically reference variable in object Ian Kelly <ian.g.kelly@gmail.com> - 2014-03-26 15:19 -0600
        Re: Dynamically reference variable in object Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2014-03-26 23:42 +0000
    Re: Dynamically reference member of array "R. Michael Weylandt" <michael.weylandt@gmail.com> - 2014-03-29 22:50 -0400

#69116 — Dynamically reference member of array

Hi all,

I know that I can dynamically reference a variable with locals()["i"], for instance, but I'd like to know how to do this with a variable in an object.

If I have an object called "device", with variables called attr1, attr2 .. attr50, how could I dynamically reference these?

It's fairly academic, but I'd like to avoid code duplication.

Thanks,

Ben

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#69117 — Dynamically reference variable in object

Sorry, subject was wrong. Please see below:

On Wednesday, 26 March 2014 11:43:49 UTC, Ben Collier  wrote:
> Hi all,
> 
> 
> 
> I know that I can dynamically reference a variable with locals()["i"], for instance, but I'd like to know how to do this with a variable in an object.
> 
> 
> 
> If I have an object called "device", with variables called attr1, attr2 .. attr50, how could I dynamically reference these?
> 
> 
> 
> It's fairly academic, but I'd like to avoid code duplication.
> 
> 
> 
> Thanks,
> 
> 
> 
> Ben

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#69143 — Re: Dynamically reference variable in object

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On Mar 26, 2014 5:48 AM, "Ben Collier" <bmcollier@gmail.com> wrote:
>
> Sorry, subject was wrong. Please see below:
>
> On Wednesday, 26 March 2014 11:43:49 UTC, Ben Collier  wrote:
> > Hi all,
> > I know that I can dynamically reference a variable with locals()["i"],
for instance, but I'd like to know how to do this with a variable in an
object.
> > If I have an object called "device", with variables called attr1, attr2
.. attr50, how could I dynamically reference these?
> > It's fairly academic, but I'd like to avoid code duplication.

You want to access object "attributes", not "variables".  You can do this
using the functions getattr and setattr like so:

>>> class Foo(object): pass
...
>>> obj = Foo()
>>> setattr(obj, "x", 42)
>>> print(obj.x)
42
>>> print(getattr(obj, "x"))
42

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#69153 — Re: Dynamically reference variable in object

On Wed, 26 Mar 2014 15:19:03 -0600, Ian Kelly wrote:

> You want to access object "attributes", not "variables".

In fairness to the OP, the terminology "instance variables" meaning 
attributes or members of an instance is (sadly, in my opinion) common in 
some other languages, such as Java, and occasionally creeps into even the 
Python docs.

I've often ranted about this, and won't repeat it now, only point out 
that the preferred and most common terminology in Python circles is 
"attribute", or "instance attribute" if you need to distinguish it from 
"class attribute".



-- 
Steven D'Aprano
http://import-that.dreamwidth.org/

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#69365

On Wed, Mar 26, 2014 at 7:43 AM, Ben Collier <bmcollier@gmail.com> wrote:
> Hi all,
>
> I know that I can dynamically reference a variable with locals()["i"], for instance, but I'd like to know how to do this with a variable in an object.
>
> If I have an object called "device", with variables called attr1, attr2 .. attr50, how could I dynamically reference these?
>

I think the pythonic term you're looking for is "attribute". See
getattr() and setattr()

Cheers,
Michael

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