Stephen Hansen wrote:
On 6/26/10 9:01 AM, Alexander Kapps wrote:
While I personally don't agree with this proposal (but I understand why
some people might want it), I can see a reason.
When disallowing direct attribute creation, those typos that seem to
catch newcommers won't happen anymore. What I mean is this:
I get where you're coming from, but I don't see why "attributes" should
get such special typo-protection when locals and any other names shouldn't.
Well, I would sympathize with an attempt to add some kind of typo
protection. Not build into the language, but I dream about a command
line switch that invokes a test like pylint/PyChecker. I wish any of
those would enter the standard distribution.
I see it as an extension of "Special cases aren't special enough to
break the rules." -- and here I think the OP and I disagree most strongly.
This characterization of adding attributes to an object as something
"else", some special kind of activity called "metaprogramming" I think I
reject outright, whereas I believe -- though I do not claim to speak for
him/her -- the OP's position is that using 'syntax' to add attributes is
actually a special case/activity.
I consider it the standard, normal behavior.
If this is how I create a local variable:
x = 1
And to read that variable, I simply refer to it as "x", and if to read a
defined attribute from an object I do:
a.x
Then, to me, the way in which I would set a new variable on that object
is clearly:
a.x = 1
I don't see why Python should special case setting an attribute on an
object to be so wildly different then setting a local variable (or
global, or anything else) as to require a special function call. The
activity of "adding an attribute to an object" is no more special, IMHO,
then "adding a variable to the local scope".
I fully agree with everything so far. As I said, i don't support
this proposal, just that I can see a reason why some people might
want this. I do this type of dynamic attribute addition (both data
and methods) all day in my interactive sessions, which are a large
part of my Python activity.
Now, true: I fully acknowledge that if you're in an OOP-mindset and
you're choosing to use a certain style of programming (and one I
frequently indulge in), then you may /choose/ to treat certain objects
as special, as being more firmly structured, as having a formal definition.
In that situation, certainly: adding an attribute on the fly to that
formal definition seems entirely strange and special of an activity. But
that's only because you *chose* to *see* and *use* the object that way.
The "special"ness of the activity is entirely in your head, and to
Python, its an entirely normal event.
That was an interesting insight, thank you for this. While I
actually know all this, I indeed still seem to sometimes treat
objects as "fixed-once-defined-and-created" entities. I just grep'ed
all my code repository and found that I almost never do any
on-the-fly attribute addition (totally contrary to my interactive work)
You may have just opened the door the my next level of Python OO
understanding. Thank you! :-)
Python lets you associate significance with normal events so you can get
things done. But its just plodding along not really drinking whatever
kool-aid you are, though its happy you like your flavor and is entirely
content with letting you think its playing ball with you on that.
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