[Zope] More failed attempts with python

[Paul Winkler]

On Sat, Aug 16, 2003 at 05:16:36PM -0700, Bill Hewitt wrote:
> Hello again folks...
> Below is what I have written in attempting to dynamically
> construct a variable name, then retrieve the value of the 
> variable from the namespace in python.

(snip)
 
> newstring="%scolor" % (type)

fine...

> # Next I want to 
> # retrieve the *value* for preferredcolor by evaluating the string I
> created in the variable newstring
> # I cant seem to get this to work......
> preferredcolor=container.newstring

There's your problem. You are literally asking for
an attribute of the container named "newstring". 

What you want is:

getattr(container, newstring)

It's worth playing with this stuff in the python interpreter until you
really understand it. For example, see if you follow this:

$ python
Python 2.2.3 (#1, Jul 22 2003, 12:28:47) 
[GCC 3.2.3 20030422 (Gentoo Linux 1.4 3.2.3-r1, propolice)] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> class C:  
...     def __init__(self):
...         self.width = 10  
...         self.height = 2
... 
>>> c = C()
>>> c.width
10
>>> c.height
2
>>> # So far so good.
>>> dimension = 'width'
>>> c.dimension  
Traceback (most recent call last):
  File "<stdin>", line 1, in ?
AttributeError: C instance has no attribute 'dimension'
>>> getattr(c, dimension) 
10
>>> getattr(c, 'dimension')
Traceback (most recent call last):
  File "<stdin>", line 1, in ?
AttributeError: C instance has no attribute 'dimension'
>>> 


-- 

Paul Winkler
http://www.slinkp.com
Look! Up in the sky! It's META FISHY SKORPION!
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