which a is used?

[Jayden]

Dear All,

I have a simple code as follows:

# Begin
a = 1

def f():
print a

def g():
a = 20
f()

g()
#End

I think the results should be 20, but it is 1. Would you please tell me why?

Thanks a lot!

[Dwight Hutto]

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

didn't return the value, or print it out


--
Best Regards,
David Hutto
CEO: http://www.hitwebdevelopment.com

[Dwight Hutto]

On Mon, Sep 24, 2012 at 7:57 PM, Dwight Hutto <dwight...@gmail.com> wrote:
> On Mon, Sep 24, 2012 at 7:43 PM, Jayden <jayde...@gmail.com> wrote:

>> Dear All,
>>
>> I have a simple code as follows:
>>
>> # Begin
>> a = 1
>>
>> def f():
>> print a
>>
>> def g():
>> a = 20
>> f()

this prints a from calling f() function

call print a wasn't in a class where it was self.a and changed, so it
performed the function f which prints a and a = 1, but g just assigns
the 20, and calls the f() function which shows a, there is no self.a,
nor a class to show this in.

>>
>> g()
>> #End
>>
>> I think the results should be 20, but it is 1. Would you please tell me why?
>>
>> Thanks a lot!
>>

[alex23]

Because you don't declare 'a' in 'f', it looks for 'a' in the
surrounding scope _where it was defined_, not where it was called.
Because 'a' in the module scope is 1, you'll get 1.

[Dwight Hutto]

Anything else bitch, take time to think about it.

[Steven D'Aprano]

You are expecting "dynamic scoping", Python uses "static scoping" (or
lexical scoping). With lexical scoping, you can reason about the
behaviour of a function by knowing only how and where it is defined. The
caller is irrelevant.

Since function f is defined globally, and does not have its own local
variable a, it will always see the global variable a no matter where it
is called. So when you call f() from inside g(), f prints 1, the global
a, not 20, g's local a.

While dynamic scoping has its uses, it is more tricky to use correctly.
One can no longer understand the behaviour of a function just by reading
the function's own code, knowing where and how it is defined. You also
need to know where it is called. A function f that works perfectly when
you call it from functions g, h, k, ... will suddenly misbehave (crash,
or worse, behave wrongly) when called from function v because v
accidentally changes some global variable that f relies on.

This is especially a danger for Python, because built-in functions like
len, chr, ord, print (version 3 only), and many others are all global
variables.

(Technically, they are in a third scope, the builtins, but that's
equivalent to being global.)



--
Steven

[Dwight Hutto]

On Mon, Sep 24, 2012 at 9:18 PM, Steven D'Aprano
<steve+comp....@pearwood.info> wrote:
> On Mon, 24 Sep 2012 16:43:24 -0700, Jayden wrote:
>
>> Dear All,
>>
>> I have a simple code as follows:
>>
>> # Begin
>> a = 1
>>
>> def f():
>> print a

>>Paul Rubin <no.e...@nospam.invalid>

>> def g():
>> a = 20
>> f()
>>
>> g()
>> #End
>>
>> I think the results should be 20, but it is 1. Would you please tell me
>> why?
>
> You are expecting "dynamic scoping", Python uses "static scoping" (or
> lexical scoping). With lexical scoping, you can reason about the

> behavioPaul Rubin <no.e...@nospam.invalid>ur of a function by knowing only how and where it is defined. The
> caller is irrelevant.
>
> Since fuPaul Rubin <no.e...@nospam.invalid>nction f is defined globally, and does not have its own local

> variable a, it will always see the global variable a no matter where it
> is called. So when you call f() from inside g(), f prints 1, the global
> a, not 20, g's local a.
>
> While dynamic scoping has its uses, it is more tricky to use correctly.
> One can no longer understand the behaviour of a function just by reading

> the funcPaul Rubin <no.e...@nospam.invalid>tion's own code, knowing where and how it is defined. You also

> need to know where it is called. A function f that works perfectly when
> you call it from functions g, h, k, ... will suddenly misbehave (crash,
> or worse, behave wrongly) when called from function v because v
> accidentally changes some global variable that f relies on.
>
> This is especially a danger for Python, because built-in functions like
> len, chr, ord, print (version 3 only), and many others are all global
> variables.
>
> (Technically, they are in a third scope, the builtins, but that's
> equivalent to being global.)
>

But within a class this is could be defined as self.x within the
functions and changed, correct?


class a():
def __init__(self,a):
self.a = a

def f(self):
print self.a

def g(self):
self.a = 20
print self.a


a = a(1)
a.f()
a.g()


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

[Dwight Hutto]

But within a class this is could be defined as self.x within the
functions and changed, correct?


class a():
def __init__(self,a):
self.a = a

def f(self):
print self.a

def g(self):
self.a = 20
print self.a


a = a(1)
a.f()
a.g()

Yielding:

david@david-desktop:~$ python answer_to_email.py
1
20
david@david-desktop:~$

[alex23]

On Sep 25, 11:13 am, Dwight Hutto <dwightdhu...@gmail.com> wrote:
> bitch

I honestly could not care less what you think about me, but don't use
that term. This isn't a boys' club and we don't need your hurt ego
driving people away from here.

[Dwight Hutto]

> I honestly could not care less what you think about me, but don't use
> that term. This isn't a boys' club and we don't need your hurt ego
> driving people away from here.

OOOOOOOOOHHHHH. stirrin up shit and can't stand the smell. Turn and
switch technique. "You're so vulgar, and I wasn't."Go get a clue ho,
and then you can gumshoe it up the last crack alley on the left, and
suck till my nut hair tickles your tonsils.




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

[Terry Reedy]

Revising my answer to your other post.

On 9/24/2012 9:13 PM, Dwight Hutto wrote:
> Anything else bitch, take time to think about it.

This is completely bizarre, and uncalled for as an apparent response to
Alex. Your next response is too dirty to read, let alone quote. Please
desist. If necessary, learn to wait a few minutes before hitting send.


--
Terry Jan Reedy

[Thomas Rachel]

Am 25.09.2012 03:13 schrieb Dwight Hutto:

> Anything else bitch, take time to think about it.

And you wonder if people don't like you because of your language?


Thomas

[Thomas Rachel]

Am 25.09.2012 03:47 schrieb Dwight Hutto:

> But within a class this is could be defined as self.x within the
> functions and changed, correct?
>
>
> class a():
> def __init__(self,a):
> self.a = a
>
> def f(self):
> print self.a
>
> def g(self):
> self.a = 20
> print self.a
>
>
> a = a(1)
> a.f()
> a.g()

Yes - this is a different situation. Here, the "self" referred to is the
same in all cases (the "a" from top level), and so self.a can be used
consistently as well.


Thomas

[Thomas Rachel]

Am 25.09.2012 04:37 schrieb Dwight Hutto:
>> I honestly could not care less what you think about me, but don't use
>> that term. This isn't a boys' club and we don't need your hurt ego
>> driving people away from here.
>
> OOOOOOOOOHHHHH. stirrin up shit and can't stand the smell.

Where did he so?


Thomas

[Dwight Hutto]

On Tue, Sep 25, 2012 at 1:06 AM, Thomas Rachel
<nutznetz-0c1b6768-bfa9...@spamschutz.glglgl.de>
wrote:

> Am 25.09.2012 03:13 schrieb Dwight Hutto:
>
>
>> Anything else bitch, take time to think about it.
>
>
> And you wonder if people don't like you because of your language?
>

No, not really. If you wanna talk shit, I can reflect that, and if you
wanna talk politely I can reflect that. I go t attacked first., and
project managers don't get shoved around, they listen, respond, and if
wrong correct themselves, if not, they slam back , or their position
gets taken.
>
> Thomas
>
> --
> http://mail.python.org/mailman/listinfo/python-list

[Dwight Hutto]

>> OOOOOOOOOHHHHH. stirrin up shit and can't stand the smell.
>
>
> Where did he so?
>

You'd have to read the other posts. And remember that some of these
names are A.K.A.'s, they ask respond, and befriend another name
through another proxy.

[Thomas Rachel]

Am 25.09.2012 07:22 schrieb Dwight Hutto:

> No, not really. If you wanna talk shit, I can reflect that, and if you
> wanna talk politely I can reflect that. I go t attacked first.,

But not in this thread.

Some people read only selectively and see only your verbal assaults,
without noticing that they refer to.

If you was really insulted, you should answer to these insults in their
thread and not in a different one.


Thomas

[Mark Lawrence]

He's referring to threads on the tutor mailing list where I have
repeatedly asking him to provide context when he replies. Unfortunately
he doesn't seem to understand the term context so resorts to attacking
me. In a part of one thread he referred to my family as pigs. I've
have lived with that, using the sticks and stones reply, but then
someone had the audacity to protect his stance. I am sure that people
have seen enough of his behaviour in the last few hours to see the real
Dwight Hutto so I'll leave it at that.

--
Cheers.

Mark Lawrence.

[Alain Ketterlin]

Jayden <jayde...@gmail.com> writes:

> # Begin
> a = 1
>
> def f():
> print a
>
> def g():
> a = 20
> f()
>
> g()
> #End
>
> I think the results should be 20, but it is 1. Would you please tell me why?

When python looks at g(), it sees that a variable a is assigned to, and
decides it is a local variable. When it looks at f(), it sees a use of a
but no assignment, so it decides it is a global variable and fetches the
value from the outer scope.

If you change f() to:

def f():
print a
a = 30

you change a into a local variable (and get another error).

If you want to change the binding of a in g(), you can declare it
global:

def g():
global a
a = 20
f()

Very tricky, actually.

-- Alain.

[alex23]

On Sep 25, 3:30 pm, Dwight Hutto <dwightdhu...@gmail.com> wrote:
> You'd have to read the other posts. And remember that some of these
> names are A.K.A.'s, they ask respond, and befriend another name
> through another proxy.

You've actively accused me of this several times. If you have evidence
that there's sockpuppeting, please provide it.

[Colin J. Williams]

+1

[D'Arcy Cain]

On Tue, 25 Sep 2012 08:44:18 +0100
Mark Lawrence <bream...@yahoo.co.uk> wrote:
> On 25/09/2012 06:07, Thomas Rachel wrote:

> > Am 25.09.2012 04:37 schrieb Dwight Hutto:

[...usual nonsense]

> someone had the audacity to protect his stance. I am sure that people
> have seen enough of his behaviour in the last few hours to see the real
> Dwight Hutto so I'll leave it at that.

Now if only people would stop feeding the troll, those of us who have
already *plonked* him can stop seeing his ramblings in the responses.

--
D'Arcy J.M. Cain <da...@druid.net> | Democracy is three wolves
http://www.druid.net/darcy/ | and a sheep voting on
+1 416 425 1212 (DoD#0082) (eNTP) | what's for dinner.
IM: da...@Vex.Net

[David Robinow]

On Tue, Sep 25, 2012 at 9:53 AM, D'Arcy Cain <da...@druid.net> wrote:
> ...

> Now if only people would stop feeding the troll, those of us who have
> already *plonked* him can stop seeing his ramblings in the responses.

I'm hating myself for jumping in to this nonsense, but ...
+1

[Dwight Hutto]

You can "Plonk" my dick bitches.

[Dwight Hutto]

On Wed, Sep 26, 2012 at 3:06 AM, Dwight Hutto <dwight...@gmail.com> wrote:
> You can "Plonk" my dick bitches.
>
>

> --
> Best Regards,
> David Hutto
> CEO: http://www.hitwebdevelopment.com

+5.75

[alex23]

On Sep 26, 5:06 pm, Dwight Hutto <dwightdhu...@gmail.com> wrote:
> You can "Plonk" my dick bitches.

You do understand that when you have so many people react badly to how
you phrase things, that the problem most likely lies with you and not
them? That the only person who actually reacts favourably to this
garbage coming from you is *you*?

There is no place for racist or sexist speech here. Reply personally
to whomever you want with whatever invective you choose, that's your
right (just as it is their right to flag your emails as spam, as I
have). But this is a place for public discussion and, again, we do not
need you driving away people who might actually contribute positively
simply because you're unable or unwilling to always do so.

[Ben Finney]

alex23 <wuw...@gmail.com> writes:

> On Sep 26, 5:06 pm, Dwight Hutto <dwightdhu...@gmail.com> wrote:
> > You can "Plonk" my dick bitches.
>
> You do understand that when you have so many people react badly to how
> you phrase things, that the problem most likely lies with you and not
> them? That the only person who actually reacts favourably to this
> garbage coming from you is *you*?

There have been ample opportunities for him to realise this. It's past
time to stop feeding this troll, please.

--
\ “Alternative explanations are always welcome in science, if |
`\ they are better and explain more. Alternative explanations that |
_o__) explain nothing are not welcome.” —Victor J. Stenger, 2001-11-05 |
Ben Finney

[Dwight Hutto]

It's past
> time to stop feeding this troll, please.

You mean like the post above you sent....bitch please, I'm eatin good right now.

[Dwight Hutto]

On Wed, Sep 26, 2012 at 8:40 PM, alex23 <wuw...@gmail.com> wrote:
> On Sep 26, 5:06 pm, Dwight Hutto <dwightdhu...@gmail.com> wrote:
>> You can "Plonk" my dick bitches.
>
> You do understand that when you have so many people react badly to how
> you phrase things, that the problem most likely lies with you and not
> them?

Depends on the demographic.

That the only person who actually reacts favourably to this
> garbage coming from you is *you*?

Yeah...I'm egotistical.

>
> There is no place for racist or sexist speech here. \

There never was any from me

Reply personally
> to whomever you want with whatever invective you choose, that's your
> right (just as it is their right to flag your emails as spam, as I
> have).

Yeah, hit the mute button if you don't like me. That's a brilliant
fucking idea...buddy.

But this is a place for public discussion and, again, we do not
> need you driving away people who might actually contribute positively
> simply because you're unable or unwilling to always do so.

Uhm, I do post appropriately, unless you're trolling the board, with a
few other avatars, and buddies in order to stomp a flame war someone
else started...IMHO.

[Chris Angelico]

On Fri, Sep 28, 2012 at 1:47 PM, Dwight Hutto <dwight...@gmail.com> wrote:
> [ lots of screed that demonstrates that Dwight hasn't grokked the hacker culture ]

Dwight, have a read of these documents. They may help you to
understand how the python-list community operates, and perhaps more
so, why most of the regulars here think the way they do. Actually,
this may be of interest to quite a few people, so I'll post it
on-list.

http://catb.org/~esr/faqs/

ChrisA

[Dwight Hutto]

On Fri, Sep 28, 2012 at 12:40 AM, Chris Angelico <ros...@gmail.com> wrote:
> On Fri, Sep 28, 2012 at 1:47 PM, Dwight Hutto <dwight...@gmail.com> wrote:
>> [ lots of screed that demonstrates that Dwight hasn't grokked the hacker culture ]

Don't hack, but could very well if necessary.

>
> Dwight, have a read of these documents. They may help you to
> understand how the python-list community operates, and perhaps more
> so, why most of the regulars here think the way they do.

They have double digit I.Q.'s ?

Actually,
> this may be of interest to quite a few people, so I'll post it
> on-list.

Go right ahead....buddy.

>
> http://catb.org/~esr/faqs/
>
> ChrisA
> --
> http://mail.python.org/mailman/listinfo/python-list

[Littlefield, Tyler]

On 9/27/2012 10:50 PM, Dwight Hutto wrote:
> On Fri, Sep 28, 2012 at 12:40 AM, Chris Angelico <ros...@gmail.com> wrote:
>> On Fri, Sep 28, 2012 at 1:47 PM, Dwight Hutto <dwight...@gmail.com> wrote:
>>> [ lots of screed that demonstrates that Dwight hasn't grokked the hacker culture ]
> Don't hack, but could very well if necessary.

You couldn't hack your self out of a wet paper bag, and you're fooling noone. Sorry... buddy. You should go away now; You asked who is laughing at you the other day, and at that point you had the ability to salvage (or at least attempt to salvage) your reputation with a few people. You've pretty much blown that away at this point, so a belated answer to your question is everyone.

>> Dwight, have a read of these documents. They may help you to
>> understand how the python-list community operates, and perhaps more
>> so, why most of the regulars here think the way they do.
> They have double digit I.Q.'s ?
>
> Actually,
>> this may be of interest to quite a few people, so I'll post it
>> on-list.
> Go right ahead....buddy.
>
>> http://catb.org/~esr/faqs/
>>
>> ChrisA
>> --
>> http://mail.python.org/mailman/listinfo/python-list
>
>


--

Take care,
Ty
http://tds-solutions.net
The aspen project: a barebones light-weight mud engine:
http://code.google.com/p/aspenmud
He that will not reason is a bigot; he that cannot reason is a fool; he that dares not reason is a slave.

[Dwight Hutto]

On Fri, Sep 28, 2012 at 1:12 AM, Littlefield, Tyler <ty...@tysdomain.com> wrote:
> On 9/27/2012 10:50 PM, Dwight Hutto wrote:
>>
>> On Fri, Sep 28, 2012 at 12:40 AM, Chris Angelico <ros...@gmail.com> wrote:
>>>
>>> On Fri, Sep 28, 2012 at 1:47 PM, Dwight Hutto <dwight...@gmail.com>
>>> wrote:
>>>>
>>>> [ lots of screed that demonstrates that Dwight hasn't grokked the hacker
>>>> culture ]
>>
>> Don't hack, but could very well if necessary.
>
>
> You couldn't hack your self out of a wet paper bag, and you're fooling
> noone.

Yeah I could.

Sorry... buddy. You should go away now;

So you can dominate with a lame ass attempt to approach my responses
with a manipulative tactic to discredit me, including such hits as
racism, and sexism?

You asked who is laughing at
> you the other day, and at that point you had the ability to salvage (or at
> least attempt to salvage) your reputation with a few people.

Nobody, they're laughing at your failed attempt to discredit me in a
on thread response in which I was a respondent.

Please don't disguise your foolishnish with lies.

You've pretty
> much blown that away at this point, so a belated answer to your question is
> everyone.

You mean I went to sleep, woke up and responded? Nice attempt, but you
can set a random seed of mine up your ass.

>
>
>>> Dwight, have a read of these documents. They may help you to
>>> understand how the python-list community operates, and perhaps more
>>> so, why most of the regulars here think the way they do.
>>
>> They have double digit I.Q.'s ?
>>
>> Actually,
>>>
>>> this may be of interest to quite a few people, so I'll post it
>>> on-list.
>>
>> Go right ahead....buddy.
>>
>>> http://catb.org/~esr/faqs/
>>>
>>> ChrisA
>>> --
>>> http://mail.python.org/mailman/listinfo/python-list
>>
>>
>>
>
>
> --
> Take care,
> Ty
> http://tds-solutions.net
> The aspen project: a barebones light-weight mud engine:
> http://code.google.com/p/aspenmud
> He that will not reason is a bigot; he that cannot reason is a fool; he that
> dares not reason is a slave.
>

[rusi]

On Sep 28, 10:21 am, Dwight Hutto <dwightdhu...@gmail.com> wrote:
> On Fri, Sep 28, 2012 at 1:12 AM, Littlefield, Tyler <ty...@tysdomain.com> wrote:
> > On 9/27/2012 10:50 PM, Dwight Hutto wrote:
>
> >> On Fri, Sep 28, 2012 at 12:40 AM, Chris Angelico <ros...@gmail.com> wrote:
>

> >>> On Fri, Sep 28, 2012 at 1:47 PM, Dwight Hutto <dwightdhu...@gmail.com>

Some facts that are well-known enough but somehow seem relevant to
this discussion.
Technology is called a great enabler -- A little less gushingly its a
great multiplier.
When we look a little impartially at it we see that as technology
increases in scope/power the corresponding human involvement gets more
and more passive.

Coming to the specific technology-stack -- mailing-lists atop the
internet -- we see the following:
When I hit the send button Ive no idea who will read what I send.
Likewise what I end up reading may not be something I specifically
wish to read.

Specifically, Ive no idea what is the size of the python-list
readership -- surely in hundreds, more likely thousands.

So when I feel like making a response to one or two people which has
more heat than (python-related) light, it would help to consider the
thousand(s) who will read it who are not involved/interested in the
fracas.

A more physical analogy: Lets say I am driving along happily on the
freeway and someone does something to me that generates severe
justifiable road-rage. So I stop the car, get down and do my schtick
-- shout, shoot, mow-him-down, whatever -- and in the process create a
jam of a hundred vehicles all around. However justifiable my rage, I
would be lucky to get anyone's support!

A more personal point. I find that anger is usually a thin cover for
depression. And depression inversely correlates with amount of
sunshine I see. So before hitting the send button, it may be a good
idea to sleep over and see if the rising sun changes my mood.

Coming to threads like this one:
We've seen an old member of this list scolded for stretching the
drinking jokes a bit too far.
And another old member who posted a youtube link which had nothing to
do with python even though the subject said 'OT'

So… Staying withing python-related discussions and using courteous
language is the general rule for all. If you follow that you should be
ok

[Dwight Hutto]

But technology should be engaged by many different view points, in
order to insure that the output of technology is within the, not only
the grasp of outsiders, but the scope of those who wish to debate it's
usage in many different areas in order to have stability of the
society(societies) that produce the output.

> Coming to the specific technology-stack -- mailing-lists atop the
> internet -- we see the following:
> When I hit the send button Ive no idea who will read what I send.
> Likewise what I end up reading may not be something I specifically
> wish to read.

That's common on mailing lists, and the discussions they maintain, as
well as the usage membership.

>
> Specifically, Ive no idea what is the size of the python-list
> readership -- surely in hundreds, more likely thousands.
>

Then it's part of, but the only side of, your public persona.

> So when I feel like making a response to one or two people which has
> more heat than (python-related) light, it would help to consider the
> thousand(s) who will read it who are not involved/interested in the
> fracas.

Don't be a little bitch, and respond. Instead you're whining about it.

>
> A more physical analogy: Lets say I am driving along happily on the
> freeway and someone does something to me that generates severe
> justifiable road-rage. So I stop the car, get down and do my schtick
> -- shout, shoot, mow-him-down, whatever -- and in the process create a
> jam of a hundred vehicles all around. However justifiable my rage, I
> would be lucky to get anyone's support!

It's called information overload, and temporary insanity...go ask a lawyer list.

>
> A more personal point. I find that anger is usually a thin cover for
> depression.

A medical condition which can be cause by many different factors, and all legal.

And depression inversely correlates with amount of
> sunshine I see.

This is more seasonal depression, and human biological adjustment to
circadian rhythm in nature that appears in several areas.

So before hitting the send button, it may be a good
> idea to sleep over and see if the rising sun changes my mood.

It always does, it's biological in nature for this to happen.

>
> Coming to threads like this one:
> We've seen an old member of this list scolded for stretching the
> drinking jokes a bit too far.

Probably me, and you have no idea what I'm not saying when if not
drinking I have severe nerve damage...that would probably blow your
own little itty bitty mind, so deal with average intelligence on your
own.

> And another old member who posted a youtube link which had nothing to
> do with python even though the subject said 'OT'
>
> So… Staying withing python-related discussions and using courteous
> language is the general rule for all. If you follow that you should be
> ok

Open mindedness is what the internet is about, if you can't be free
with emotions and internal vectors of molecular thought freedom, then
you might want ot move out of the way of the New World Order.