Dynamically reference variable in object

2014-03-26 Thread Ben Collier 
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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Re: Dynamically reference variable in object

2014-03-26 Thread Ian Kelly 
On Mar 26, 2014 5:48 AM, Ben Collier bmcoll...@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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Re: Dynamically reference variable in object

2014-03-26 Thread Steven D'Aprano 
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.



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