kj a écrit :
In 4a967b2f$0$19301$426a7...@news.free.fr Bruno Desthuilliers
bruno.42.desthuilli...@websiteburo.invalid writes:
The only thing one is entitled to expect when learning a new language is
that the language's implementation follows the language specs.
In fact, the official docs,
kj wrote:
Miles Kaufmann mile...@umich.edu writes:
...because the suite
namespace and the class namespace would get out of sync when different
objects were assigned to the class namespace:
class C:
x = 1
def foo(self):
print x
print self.x
o = C()
o.foo()
1
1
o.x = 2
In mailman.596.1251474438.2854.python-l...@python.org Ethan Furman
et...@stoneleaf.us writes:
kj wrote:
Miles Kaufmann mile...@umich.edu writes:
...because the suite
namespace and the class namespace would get out of sync when different
objects were assigned to the class namespace:
On Wednesday 26 August 2009 17:14:27 kj wrote:
As I described at length in another reply, the function in question
is not intended to be callable outside the class. And yes,
I think this might go to nub of your problem - It might help you to think as
follows:
A Python class, even after it
On Wednesday 26 August 2009 17:45:54 kj wrote:
In 02a54597$0$20629$c3e8...@news.astraweb.com Steven D'Aprano
st...@remove-this-cybersource.com.au writes:
Why are you defining a method without a self parameter?
Because, as I've explained elsewhere, it is not a method: it's a
helper function,
kj a écrit :
In jeqdncamuyvtrwjxnz2dnuvz8ludn...@bt.com Martin P. Hellwig
martin.hell...@dcuktec.org writes:
kj wrote:
cut
First, one of the goals of OO is encapsulation, not only at the
level of instances, but also at the level of classes.
Who says?
Python itself: it already offers a
On Thu, 27 Aug 2009 08:38:29 +0200, Hendrik van Rooyen wrote:
On Wednesday 26 August 2009 17:14:27 kj wrote:
As I described at length in another reply, the function in question is
not intended to be callable outside the class. And yes,
I think this might go to nub of your problem - It
On Thu, 27 Aug 2009 09:09:21 +0200, Hendrik van Rooyen wrote:
On Wednesday 26 August 2009 17:45:54 kj wrote:
In 02a54597$0$20629$c3e8...@news.astraweb.com Steven D'Aprano
st...@remove-this-cybersource.com.au writes:
Why are you defining a method without a self parameter?
Because, as I've
kj wrote:
No, the fact() function here represents an internal helper
function. It is meant to be called only once to help initialize
a class variable that would be inconvenient to initialize otherwise;
this helper function is not meant to be called from outside the
class statement.
That, to
Ulrich Eckhardt wrote:
Ulrich Eckhardt wrote:
Jean-Michel Pichavant wrote:
class Color:
def __init__(self, r, g,b):
pass
BLACK = Color(0,0,0)
It make sens from a design point of view to put BLACK in the Color
namespace. But I don't think it's possible with python.
kj wrote:
I think I understand the answers well enough. What I *really*
don't understand is why this particular feature of Python (i.e.
that functions defined within a class statement are forbidden from
seeing other identifiers defined within the class statement) is
generally considered to be
In mailman.509.1251373513.2854.python-l...@python.org Jean-Michel Pichavant
jeanmic...@sequans.com writes:
kj wrote:
I think I understand the answers well enough. What I *really*
don't understand is why this particular feature of Python (i.e.
that functions defined within a class statement
On Thu, 27 Aug 2009 13:45:00 +0200, Jean-Michel Pichavant wrote:
in foo.py:
a = 5
b = a # works fine
class A:
c = 5
d = c # broken
Incorrect. That works fine.
class A:
... c = 5
... d = c # not actually broken
...
A.c
5
A.d
5
The class is a scope, and inside the
In mailman.509.1251373513.2854.python-l...@python.org Jean-Michel Pichavant
jeanmic...@sequans.com writes:
in foo.py:
a = 5
b = a # works fine
def foo(self):
e = 5
f = e #works fine
It may be solved by creating the class upon the class statement. If
the class A object
In 02a6427a$0$15633$c3e8...@news.astraweb.com Steven D'Aprano
st...@remove-this-cybersource.com.au writes:
On Thu, 27 Aug 2009 09:09:21 +0200, Hendrik van Rooyen wrote:
On Wednesday 26 August 2009 17:45:54 kj wrote:
In 02a54597$0$20629$c3e8...@news.astraweb.com Steven D'Aprano
Jean-Michel Pichavant a écrit :
kj wrote:
I think I understand the answers well enough. What I *really*
don't understand is why this particular feature of Python (i.e.
that functions defined within a class statement are forbidden from
seeing other identifiers defined within the class
On Thu, 27 Aug 2009 09:10:46 +0100
Stephen Fairchild someb...@somewhere.com wrote:
So why didn't you delete it after you were done with it?
Class Demo(object):
That should be class.
_classvar = fact(5)
del fact()
I suppose you mean del fact.
--
D'Arcy J.M. Cain da...@druid.net
On Thursday 27 August 2009 11:14:41 Steven D'Aprano wrote:
On Thu, 27 Aug 2009 08:38:29 +0200, Hendrik van Rooyen wrote:
On Wednesday 26 August 2009 17:14:27 kj wrote:
As I described at length in another reply, the function in question is
not intended to be callable outside the class. And
On Thursday 27 August 2009 11:31:41 Steven D'Aprano wrote:
What you are calculating might actually be quite complicated to enter as
a literal. You might have something like:
8 -- Complicated Table Example ---
Me? - never! I am just an assembler
In 4a967b2f$0$19301$426a7...@news.free.fr Bruno Desthuilliers
bruno.42.desthuilli...@websiteburo.invalid writes:
The only thing one is entitled to expect when learning a new language is
that the language's implementation follows the language specs.
In fact, the official docs, when they discuss
14:17:15 Steven D'Aprano st...@remove-this-cybersource.com.au wrote:
The class is a scope, and inside the class scope, you can access local
names. What you can't do is access the class scope from inside nested
functions.
s/from inside nested functions/from inside nested scopes
Besides that
On Aug 26, 2009, at 1:11 PM, kj wrote:
I think I understand the answers well enough. What I *really*
don't understand is why this particular feature of Python (i.e.
that functions defined within a class statement are forbidden from
seeing other identifiers defined within the class statement) is
kj no.em...@please.post (k) wrote:
k No, the fact() function here represents an internal helper
k function. It is meant to be called only once to help initialize
k a class variable that would be inconvenient to initialize otherwise;
k this helper function is not meant to be called from outside
Miles Kaufmann mile...@umich.edu writes:
On Aug 26, 2009, at 1:11 PM, kj wrote:
I think I understand the answers well enough. What I *really*
don't understand is why this particular feature of Python (i.e.
that functions defined within a class statement are forbidden from
seeing other
On Fri, Aug 28, 2009 at 9:49 AM, kj no.em...@please.post wrote:
Miles Kaufmann mile...@umich.edu writes:
...because the suite
namespace and the class namespace would get out of sync when different
objects were assigned to the class namespace:
class C:
x = 1
def foo(self):
kj wrote:
But this unfortunate situation is already possible, because one
can already define
class C:
x = 1
def foo(self):
print C.x
print self.x
How is this a problem? There is no ambiguity between the global scope and
the local from within foo.
From within foo
On Aug 27, 2009, at 4:49 PM, kj wrote:
Miles Kaufmann mile...@umich.edu writes:
Guido's design justifications:
http://mail.python.org/pipermail/python-dev/2000-November/010598.html
Ah! Clarity! Thanks! How did you find this? Did you know of
this post already? Or is there some special
On Fri, Aug 28, 2009 at 1:27 PM, Miles Kaufmann mile...@umich.edu wrote:
You're right, of course. If I had been thinking properly, I would have
posted this:
... the suite namespace and the class namespace would get out of sync when
different objects were assigned to the class namespace:
On Fri, Aug 28, 2009 at 1:48 PM, Xavier Ho cont...@xavierho.com wrote:
Class already provides some kind of scoping/namespace, that is the locals()
method for the class. What is pypothetical about this, if you could
elaborate?
Obviously that was supposed to be hypothetical. Oops.
--
Jean-Michel Pichavant wrote:
class Color:
def __init__(self, r, g,b):
pass
BLACK = Color(0,0,0)
It make sens from a design point of view to put BLACK in the Color
namespace. But I don't think it's possible with python.
class Color:
...
setattrib(Color, BLACK,
In mailman.407.1251237485.2854.python-l...@python.org John Posner
jjpos...@optimum.net writes:
Stephen Hansen said:
This sounds like a fundamental confusion -- a namespace is not
equivalent to a scope, really, I think.
...
snip
Hmm. I can't find Stephen Hansen's original post anywhere.
In 7figv3f2m3p0...@mid.uni-berlin.de Diez B. Roggisch de...@nospam.web.de
writes:
Classes are not scopes.
This looks to me like a major wart, on two counts.
First, one of the goals of OO is encapsulation, not only at the
level of instances, but also at the level of classes. Your comment
Ulrich Eckhardt wrote:
Jean-Michel Pichavant wrote:
class Color:
def __init__(self, r, g,b):
pass
BLACK = Color(0,0,0)
It make sens from a design point of view to put BLACK in the Color
namespace. But I don't think it's possible with python.
class Color:
...
Ulrich Eckhardt wrote:
Jean-Michel Pichavant wrote:
class Color:
def __init__(self, r, g,b):
pass
BLACK = Color(0,0,0)
It make sens from a design point of view to put BLACK in the Color
namespace. But I don't think it's possible with python.
class Color:
...
kj wrote:
cut
First, one of the goals of OO is encapsulation, not only at the
level of instances, but also at the level of classes.
Who says?
Anyway, you could be right (I am not capable to judge it) and Python
should change on this issue but from what I gathered, Pythons OO is
inspired by
On Aug 25, 7:26 pm, Dave Angel da...@ieee.org wrote:
Stephen Fairchild wrote:
You are trying to run code in a class that does not exist yet.
def Demo():
def fact(n):
if n 2:
return 1
else:
return n * fact(n - 1)
return type(Demo,
In jeqdncamuyvtrwjxnz2dnuvz8ludn...@bt.com Martin P. Hellwig
martin.hell...@dcuktec.org writes:
kj wrote:
cut
First, one of the goals of OO is encapsulation, not only at the
level of instances, but also at the level of classes.
Who says?
Python itself: it already offers a limited form of
In 16b72319-8023-471c-ba40-8025aa6d4...@a26g2000yqn.googlegroups.com Carl
Banks pavlovevide...@gmail.com writes:
First, one of the goals of OO is encapsulation, not only at the
level of instances, but also at the level of classes. =A0Your comment
suggests that Python does not fully support
7stud wrote:
On Aug 25, 7:26 pm, Dave Angel da...@ieee.org wrote:
Stephen Fairchild wrote:
You are trying to run code in a class that does not exist yet.
def Demo():
def fact(n):
if n 2:
return 1
else:
return n * fact(n - 1)
kj wrote:
Is there any good reason (from the point of view of Python's overall
design) for not fixing this?
Python is not a compiled language, in the sense that a compiler can go back
and forth over the program, filling in the details that make the program
runnable. Python is an interpreted
On Aug 26, 7:09 am, kj no.em...@please.post wrote:
In 16b72319-8023-471c-ba40-8025aa6d4...@a26g2000yqn.googlegroups.com Carl
Banks pavlovevide...@gmail.com writes:
First, one of the goals of OO is encapsulation, not only at the
level of instances, but also at the level of classes. =A0Your
kj wrote:
In 7figv3f2m3p0...@mid.uni-berlin.de Diez B. Roggisch de...@nospam.web.de
writes:
Classes are not scopes.
This looks to me like a major wart, on two counts.
First, one of the goals of OO is encapsulation, not only at the
level of instances, but also at the level of
In mailman.447.1251297107.2854.python-l...@python.org Dave Angel
da...@ieee.org writes:
Thanks for diluting my point. The OP is chasing the wrong problem. Who
cares whether a class initializer can call a method, if the method
doesn't meet its original requirements, to be callable outside the
In 1bf83a7e-f9eb-46ff-84fe-cf42d9608...@j21g2000yqe.googlegroups.com Carl
Banks pavlovevide...@gmail.com writes:
On Aug 26, 7:09=A0am, kj no.em...@please.post wrote:
In 16b72319-8023-471c-ba40-8025aa6d4...@a26g2000yqn.googlegroups.com Ca=
rl Banks pavlovevide...@gmail.com writes:
First, one
In mailman.415.1251250004.2854.python-l...@python.org Dave Angel
da...@ieee.org writes:
Stephen Fairchild wrote:
You are trying to run code in a class that does not exist yet.
def Demo():
def fact(n):
if n 2:
return 1
else:
return n * fact(n
On Aug 26, 8:13 am, Dave Angel da...@ieee.org wrote:
You can probably work around this by replacing the staticmethod
decorator with an equivalent function call:.
class Demo9(object):
def fact(n):
if n 2:
return 1
else:
return n * Demo.fact(n -
On Wed, 26 Aug 2009 10:57:32 +, kj wrote:
In 7figv3f2m3p0...@mid.uni-berlin.de Diez B. Roggisch
de...@nospam.web.de writes:
Classes are not scopes.
This looks to me like a major wart, on two counts.
First, one of the goals of OO is encapsulation, not only at the level of
instances,
In 1bf83a7e-f9eb-46ff-84fe-cf42d9608...@j21g2000yqe.googlegroups.com Carl
Banks pavlovevide...@gmail.com writes:
Yeah, it's a little surprising that you can't access class scope from
a function, but that has nothing to do with encapsulation.
It does: it thwarts encapsulation. The helper
On Wed, 26 Aug 2009 13:57:23 +, kj wrote:
In jeqdncamuyvtrwjxnz2dnuvz8ludn...@bt.com Martin P. Hellwig
martin.hell...@dcuktec.org writes:
kj wrote:
cut
First, one of the goals of OO is encapsulation, not only at the level
of instances, but also at the level of classes.
Who says?
kj wrote:
Needless to say, I'm pretty beat by this point. Any help would be
appreciated.
Thanks,
Based on your statement above, and the fact that multiple people have
now explained *exactly* why your attempt at recursion hasn't worked, it
might be a good idea to step back, accept the
In 02a54597$0$20629$c3e8...@news.astraweb.com Steven D'Aprano
st...@remove-this-cybersource.com.au writes:
On Wed, 26 Aug 2009 10:57:32 +, kj wrote:
Recursion! One of the central concepts in the theory of
functions! This is shown most clearly by the following elaboration of
my original
On Wed, 26 Aug 2009 14:09:57 +, kj wrote:
1. One of the key aspects of Python's design is that attributes must be
accessed explicitly with dot notation. Accessing class scopes from
nested functions would (seemingly) allow access to class attributes
without the dotted notation. Therefore it
On Aug 26, 8:36 am, kj no.em...@please.post wrote:
In 1bf83a7e-f9eb-46ff-84fe-cf42d9608...@j21g2000yqe.googlegroups.com Carl
Banks pavlovevide...@gmail.com writes:
Yeah, it's a little surprising that you can't access class scope from
a function, but that has nothing to do with encapsulation.
On Wed, 26 Aug 2009 15:36:35 +, kj wrote:
In 1bf83a7e-f9eb-46ff-84fe-cf42d9608...@j21g2000yqe.googlegroups.com
Carl Banks pavlovevide...@gmail.com writes:
Yeah, it's a little surprising that you can't access class scope from a
function, but that has nothing to do with encapsulation.
It
kj wrote:
class Demo(object):
def fact_iter(n):
ret = 1
for i in range(1, n + 1):
ret *= i
return ret
def fact_rec(n):
if n 2:
return 1
else:
return n * fact_rec(n - 1)
classvar1 = fact_iter(5)
kj wrote:
In 7figv3f2m3p0...@mid.uni-berlin.de Diez B. Roggisch de...@nospam.web.de
writes:
Classes are not scopes.
Classes are objects. In particular, they are (by default) instances of
class 'type'. Unless 'scopes' were instances of some other metaclass,
the statement has to be true. I
kj wrote:
I have many years of programming experience, and a few languages,
under my belt, but still Python scoping rules remain mysterious to
me. (In fact, Python's scoping behavior is the main reason I gave
up several earlier attempts to learn Python.)
Here's a toy example illustrating
In 02a54597$0$20629$c3e8...@news.astraweb.com Steven D'Aprano
st...@remove-this-cybersource.com.au writes:
http://docs.python.org/reference/executionmodel.html
It is also discussed in the PEP introducing nested scopes to Python:
http://www.python.org/dev/peps/pep-0227/
It's even eluded to in
Carl Banks wrote:
On Aug 26, 8:13 am, Dave Angel da...@ieee.org wrote:
You can probably work around this by replacing the staticmethod
decorator with an equivalent function call:.
class Demo9(object):
def fact(n):
if n 2:
return 1
else:
return n
In mailman.459.1251313091.2854.python-l...@python.org Ethan Furman
et...@stoneleaf.us writes:
Going back through the archives I found Arnaud's post with this decorator:
def bindfunc(f):
def boundf(*args, **kwargs):
return f(boundf, *args, **kwargs)
return boundf
If you use
In 7figv3f2m3p0...@mid.uni-berlin.de Diez B. Roggisch de...@nospam.web.de
writes:
But if you insist on the above methodology, you can do this:
class Demo(object):
def fact(n):
def inner(n):
if n 2:
return 1
else:
return n *
In 2a7gm6-9h@satorlaser.homedns.org Ulrich Eckhardt
eckha...@satorlaser.com writes:
kj wrote:
class Demo(object):
def fact_iter(n):
ret = 1
for i in range(1, n + 1):
ret *= i
return ret
def fact_rec(n):
if n 2:
26-08-2009 o 09:03:27 Ulrich Eckhardt eckha...@satorlaser.com wrote:
Jean-Michel Pichavant wrote:
class Color:
def __init__(self, r, g,b):
pass
BLACK = Color(0,0,0)
It make sens from a design point of view to put BLACK in the Color
namespace. But I don't think it's possible
kj wrote:
I think I understand the answers well enough. What I *really*
don't understand is why this particular feature of Python (i.e.
that functions defined within a class statement are forbidden from
seeing other identifiers defined within the class statement) is
generally considered to be
26-08-2009 o 17:45:54 kj no.em...@please.post wrote:
In 02a54597$0$20629$c3e8...@news.astraweb.com Steven D'Aprano
st...@remove-this-cybersource.com.au writes:
On Wed, 26 Aug 2009 10:57:32 +, kj wrote:
Recursion! One of the central concepts in the theory of
functions! This is shown
kj wrote:
cut
Here's a toy example illustrating what I mean. It's a simplification
of a real-life coding situation, in which I need to initialize a
private class variable by using a recursive helper function.
eh?
class Demo(object):
def fact(n):
if n 2:
return 1
kj wrote:
I have many years of programming experience, and a few languages,
under my belt, but still Python scoping rules remain mysterious to
me. (In fact, Python's scoping behavior is the main reason I gave
up several earlier attempts to learn Python.)
Here's a toy example
kj wrote:
I have many years of programming experience, and a few languages,
under my belt, but still Python scoping rules remain mysterious to
me. (In fact, Python's scoping behavior is the main reason I gave
up several earlier attempts to learn Python.)
Here's a toy example illustrating what
Diez B. Roggisch wrote
Classes are not scopes.
Too bad, could have been handy.
JM
--
http://mail.python.org/mailman/listinfo/python-list
I'm not really quite sure what voodoo I did here, but my code seems to work
in Python 3.1.1 in the following way:
class Demo(object):
def func(self, n):
return n * 5
_f = func(None, 5)
d = Demo()
print(d._f)
print(d.func(5))
# OUTPUT
25
25
So, hmm?
Regards,
Ching-Yun Xavier
On Wed, Aug 26, 2009 at 2:14 AM, Diez B. Roggisch de...@nospam.web.dewrote:
Classes are not scopes.
So the above doesn't work because name resolution inside functions/methods
looks for local variables first, then for the *global* scope. There is no
class-scope-lookup.
Sorry, I'm coming
Jean-Michel Pichavant wrote:
Diez B. Roggisch wrote
Classes are not scopes.
Too bad, could have been handy.
Nope. Because then a lot of people would write something like this:
class Foo(object):
def bar(self):
bar() # note the missing self.
And this would lead to errors
Diez said:
Classes are not scopes.
So the above doesn't work because name resolution inside functions/methods
looks for local variables first, then for the *global* scope. There is no
class-scope-lookup.
But http://docs.python.org/tutorial/classes.html says, in Section 9.3 A
First Look at
On Aug 25, 12:11 pm, John Posner jjpos...@optimum.net wrote:
Diez said:
Classes are not scopes.
So the above doesn't work because name resolution inside functions/methods
looks for local variables first, then for the *global* scope. There is no
class-scope-lookup.
7stud said:
python ignores the names inside a function when it creates the
function. This program will not produce an error:
def f():
print x
python parses the file and creates the function object and assigns the
function object to the variable f. It's not until you execute the
function
John Posner schrieb:
Diez said:
Classes are not scopes.
So the above doesn't work because name resolution inside
functions/methods
looks for local variables first, then for the *global* scope. There is no
class-scope-lookup.
But http://docs.python.org/tutorial/classes.html says, in Section
But http://docs.python.org/tutorial/classes.html says, in Section 9.3 A
First Look at Classes:
When a class definition is entered, a new namespace is created,
and used as the local scope — thus, all assignments to local variables
go into this new namespace. In particular, function
Stephen Hansen said:
But http://docs.python.org/tutorial/classes.html says, in Section
9.3 A First Look at Classes:
When a class definition is entered, a new namespace is created,
and used as the local scope — thus, all assignments to local variables
go into this new
25-08-2009 o 22:16:24 Stephen Hansen apt.shan...@gmail.com wrote:
The OP's probably is that during the execution of the class body, the
class
doesn't exist... so the 'def fact' -can't- use Classname.fact to address
itself explicitly, and within fact the locals don't contain a reference
to
You are trying to run code in a class that does not exist yet.
def Demo():
def fact(n):
if n 2:
return 1
else:
return n * fact(n - 1)
return type(Demo, (object,), {fact: staticmethod(fact), _classvar:
fact(5)})
Demo = Demo()
d = Demo()
print
Stephen Fairchild wrote:
You are trying to run code in a class that does not exist yet.
def Demo():
def fact(n):
if n 2:
return 1
else:
return n * fact(n - 1)
return type(Demo, (object,), {fact: staticmethod(fact), _classvar:
fact(5)})
Demo =
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