String.digits help!!!

[Simon Forman]

bearophileHUGS at lycos.com wrote:
> Simon Forman:
> > It's unlikely to
> > be deprecated since it doesn't make much sense to make it an attribute
> > of the str type.
>
> Why?
>
> Thank you,
> bearophile

Let me toss the question back at you:  Does it make sense to you that
str should have this attribute?  Why?


I'm not advocating for or against one thing or another, and I'm
certainly not in a position to influence the future development of
Python (anymore than any of us, that is :-) )  but FWIW, here's my
$0.02:

My "feeling" is that since str is a Type, and not a data store, it
doesn't make much sense to me to tack on a bunch of read-only data
attributes that aren't involved in it's role as a string data type just
to have a slightly more convenient way of accessing them.

There are twelve "constants" defined in the string module.  If they
were all attributes of the str type it would, for me, conceptually
"clutter up" my mental model of str, string, and python itself.

I like "from string import digits" well enough, and, as a test of my
mental model, I just used IDLE's "open module" command to find and open
string.py and discovered:

# Some strings for ctype-style character classification
whitespace = ' \t\n\r\v\f'
lowercase = 'abcdefghijklmnopqrstuvwxyz'
uppercase = 'ABCDEFGHIJKLMNOPQRSTUVWXYZ'
letters = lowercase + uppercase
ascii_lowercase = lowercase
ascii_uppercase = uppercase
ascii_letters = ascii_lowercase + ascii_uppercase
digits = '0123456789'
hexdigits = digits + 'abcdef' + 'ABCDEF'
octdigits = '01234567'
punctuation = """!"#$%&'()*+,-./:;<=>?@[\]^_`{|}~"""
printable = digits + letters + punctuation + whitespace

Exactly what I expected to find!

Really, I wouldn't be too badly shocked to discover the above string
"constants" in dir(str),  so it's kind of "six of one, a half dozen of
the other".  But on the same token, "if it's not broken, don't fix it."

Further, to make these "constants" into attributes of str, someone
would have to modify the str type at the C level to put these strings
"on" it.  Since they are str's themselves, it seems to me (having done
only trivial work with the C API of python) that that someone would
have to A) create a "first" str type, B) create these 12 strings using
that first type, C) attach them to the str type to create a "final" str
type.  And all this would have to be done at startup, I think, even if
my code didn't use these attributes.  It seems messy to me.

So to sum up, IMO, a module (rather than a type) is a good place for
these things, a module with some variable assignments is completely
within my mental model of python (i.e. no special case (of strings
being attributes of their own type (!?))), and no one has to do
anything special to make the current set up work.



By the way, I read your post a few days ago concerning adding similar
data attributes to ints and floats and found it very interesting but
not compelling.

While I would love to have the kind information you mentioned
available, I've never needed it in practice (I've only ever used
sys.maxint maybe a dozen times) and I wouldn't mind accessing it from a
module (perhaps math..  math.infinity, math.epsilon, etc., just like
math.pi and math.e.)

I look forward to hearing your thoughts an the subject.  I hope mine
haven't been too silly..  :-)

Regards,
~Simon