date:20130417

Re: Missing decimals in the code - some suggestions?

2013-04-17 Thread Steven D'Aprano

On Tue, 16 Apr 2013 12:20:18 -0600, Ian Kelly wrote:

 This isn't a Python question.  If you take a look at the csv file that
 you download from Yahoo, you will see that it only contains 2 digits of
 precision.  There's no way to make Python print out 4 digits of
 precision when it is only provided with 2.

Pish posh! It's easy to add extra precision.


py value = 2.57
py import random
py n = random.randrange(0, 100)
py value += %2d % n
py print value
2.5791


On average, your numbers will only be off by five parts in a thousand. If 
the values represent dollars, that's half a cent. Who care about half a 
cent?



Adding-spurious-precision-for-fun-and-profit-ly y'rs,


-- 
Steven
-- 
http://mail.python.org/mailman/listinfo/python-list

Re: The type/object distinction and possible synthesis of OOP and imperative programming languages

2013-04-17 Thread Steven D'Aprano

On Tue, 16 Apr 2013 15:38:29 -0700, Mark Janssen wrote:

 On Mon, Apr 15, 2013 at 3:32 PM, Chris Angelico ros...@gmail.com
 wrote:
 On Tue, Apr 16, 2013 at 8:12 AM, Rotwang sg...@hotmail.co.uk wrote:
 Traceback (most recent call last):
   File pyshell#2, line 1, in module
 class C(type(lambda: None)):
 TypeError: type 'function' is not an acceptable base type


 and I don't think that FunctionType would be considered an internal
 detail, would it? Not that I'd cite the fact that not all types can
 be inherited from as evidence that types and classes are not synonyms,
 mind.

 Actually, I'm not sure how you'd go about inheriting from a function.
 Why not just create a bare class, then assign its __call__ to be the
 function you're inheriting from?
 
 I think his point remains valid, from a theoretical pov.  Python prides
 itself on the idea of first-class functions and such, but unlike the
 world of lambda calculus, this selling point is a bit invalid.


Python functions are first-class functions, which is short-hand for 
saying functions which are also capable of being treated as values, 
which means they can be created at run-time, returned from functions, 
passed around as arguments, and assigned to variables.

Python's function type is not a first-class object-type, because it 
cannot be subclassed in at least three of the main implementations. But 
this has nothing to do with whether or not functions are first-class 
functions, which is an unrelated meaning. One can conceive of a language 
where FunctionType is a first-class type capable of being subclasses, but 
functions are *not* first-class values capable of being passed around as 
arguments.



 Because for Python (and any C-based language), 

Python-the-language is not C-based, or at least, very little of Python is 
C-based. It's main influences are, according to GvR, Lisp and ABC, with 
Pascal, Haskell and of course C also having some influence. Syntax-wise, 
it is much more of an Algol-inspired language than a C-inspired language.



 it is roots squarely in the
 Turing machine and its real-word implementation.

Python is certainly not inspired by Turing machines. Since a Turing 
machine is a simple device with an infinitely long paper tape which can 
have marks added and deleted from it, very few real programming languages 
are based on Turing machines.

It is, however, Turing-complete. Just like every programming language 
worthy of the name, whether it has syntax like Python, C, Lisp, Forth, 
INTERCAL, Oook, Applescript, Inform-7, Java, PHP, or x86 assembler.


   (Note this contrasts starkly with Java(script), which doesn't seem
 to be based on anything -- can anyone clarify where Java actually comes
 from?)

C.



-- 
Steven
-- 
http://mail.python.org/mailman/listinfo/python-list

Re: Unicode issue with Python v3.3

2013-04-17 Thread nagia . retsina

Τη Κυριακή, 14 Απριλίου 2013 12:28:32 μ.μ. UTC+3, ο χρήστης Cameron Simpson
έγραψε:
On 13Apr2013 23:00, nagia.rets...@gmail.com nagia.rets...@gmail.com wrote:

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