On 12/4/2013 3:07 PM, Piotr Dobrogost wrote:
You have proposed to make non-identifier attribute names 'official',
rather than discouraged, by abbreviating
> x = getattr(obj, 'value-1')
or
x = obj.__dict__['value-1'] # implementation detail
as
x = obj.'value-1'
The discussion of enlarging the scope of 'identifier' is not relevant as
you are not proposing that. In particular, you are not asking that
obj.value-1 get the 'value-1' attribute of obj. The discussion of
keystrokes is also a side-track.
What you are proposing, I believe, is a new grammatical category:
attribute-name := identifier or string-literal. This would break the
symmetry of the grammatical form identifier '.' identifier and change it
to the asymmetrical identifier '.' attribute-name, and that is the
problem. Most identifiers are attributes of a namespace and many
attributes are set *and accessed* as undotted names in module or class
code. The symmetry is at least partly inherent and breaking it does not
work very well.
>>> len is __builtins__.len
True
>>> __globals__ = __import__(__name__)
>>> a = 1
>>> a is __globals__.a
True
To put it another way, how does 'obj' get the non-standard attribute
'value-1', when obj is a module or class? The workaround given above for
module attributes will not work for classes.
Remember the Python philosophy that there ought to be one way to do
it.
Funny you use this argument against my idea as this idea comes from
following this rule whereas getattr goes against it.
Not really. As others have pointed out, getattr is the preferred way to
get the value of an attribute when you have an object with attributes
and a run-time-only reference to the name in a string variable.
It would also be the case that "obj.'value' is obj.value", so the
proposal *would* add duplication.
--
Terry Jan Reedy
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