[Tutor] About using list in a function

[Michelle Meiduo Wu]

Hi there,
I'm trying to use List in a function. But it doesn't work. Here are sample code not work: ---------------------------------------def getResult(): ls = [] ls= ls.append(100) ls= ls.append(200) return ls
reList = []reList = getResult()lsLength = len(reList)print '\n The length of the list is:' + str(lsLength)-----------------------------------------I ran the above code, there is an error message: AttributeError: 'NoneType' object has no attribute 'append'
But the code below not using list in a function works.----------------------------------------------### This works:ls = []ls.append(100)ls.append(200)lsLength = len(ls)print '\n list length is: ' + str(lsLength)----------------------------------------------------- Do you know the reason?
Thank you,Michelle


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[Steven D'Aprano]

Hi Michaelle, and welcome.

Hi there, I'm trying to use List in a function. But it doesn't work.
---------------------------------------
ls = []
ls = ls.append(100)

That line above is your problem. The append() method should be thought
of as a procedure that acts in place, not a function which returns a
value. So the line:

ls = ls.append(100)

sets ls to None, a special value that means "no result". Instead, you
should write this:

def getResult():
ls = []
ls.append(100)
ls.append(200)
return ls


Or you can make that even shorter:

def getResult():
ls = [100, 200]
return ls

[Steven D'Aprano]

Post by Steven D'Aprano
Hi Michaelle, and welcome.

Oops, sorry for the typo, I meant Michelle.

[Alan Gauld]

Post by Michelle Meiduo Wu
Hi there,
I'm trying to use List in a function. But it doesn't work. Here are sample code not work: ---------------------------------------def getResult(): ls = [] ls= ls.append(100) ls= ls.append(200) return ls
reList = []reList = getResult()lsLength = len(reList)print '\n The length of the list is:' + str(lsLength)-----------------------------------------I ran the above code, there is an error message: AttributeError: 'NoneType' object has no attribute 'append'
But the code below not using list in a function works.----------------------------------------------### This works:ls = []ls.append(100)ls.append(200)lsLength = len(ls)print '\n list length is: ' + str(lsLength)----------------------------------------------------- Do you know the reason?
Thank you,Michelle

As you can (hopefully!) see above, this message is completely scrambled.
Normally that means HTML. But the headers suggest it is plain text.
Also, I see that Steve replied with a correctly formatted inclusion.

Did anyone else get the scrambled version?
And does anyone have any clues why I did?

(Using Thunderbird v31.8 and normally not having major issues.)
--
Alan G
Author of the Learn to Program web site
http://www.alan-g.me.uk/
http://www.amazon.com/author/alan_gauld
Follow my photo-blog on Flickr at:
http://www.flickr.com/photos/alangauldphotos


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[Laura Creighton]

Post by Alan Gauld

Post by Michelle Meiduo Wu
Hi there,
I'm trying to use List in a function. But it doesn't work. Here are sample code not work: ---------------------------------------def getResult(): ls = [] ls= ls.append(100) ls= ls.append(200) return ls
reList = []reList = getResult()lsLength = len(reList)print '\n The length of the list is:' + str(lsLength)-----------------------------------------I ran the above code, there is an error message: AttributeError: 'NoneType' object has no attribute 'append'
But the code below not using list in a function works.----------------------------------------------### This works:ls = []ls.append(100)ls.append(200)lsLength = len(ls)print '\n list length is: ' + str(lsLength)----------------------------------------------------- Do you know the reason?
Thank you,Michelle

As you can (hopefully!) see above, this message is completely scrambled.
Normally that means HTML. But the headers suggest it is plain text.
Also, I see that Steve replied with a correctly formatted inclusion.
Did anyone else get the scrambled version?
And does anyone have any clues why I did?
(Using Thunderbird v31.8 and normally not having major issues.)

I got scrambled, same as you.

Laura

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[Laura Creighton]

Scrambled in the archives, too
https://mail.python.org/pipermail/tutor/2015-August/106528.html
And looks like something thought it would be best as only one line of
text.

Laura
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[Marc Tompkins]

Post by Alan Gauld

Post by Michelle Meiduo Wu
Hi there,
I'm trying to use List in a function. But it doesn't work. Here are
sample code not work: ---------------------------------------def
getResult(): ls = [] ls= ls.append(100) ls= ls.append(200)
return ls
reList = []reList = getResult()lsLength = len(reList)print '\n The length
of the list is:' + str(lsLength)-----------------------------------------I
ran the above code, there is an error message: AttributeError: 'NoneType'
object has no attribute 'append'
But the code below not using list in a function
works.----------------------------------------------### This works:ls =
[]ls.append(100)ls.append(200)lsLength = len(ls)print '\n list length is: '
+ str(lsLength)----------------------------------------------------- Do you
know the reason?
Thank you,Michelle

As you can (hopefully!) see above, this message is completely scrambled.
Normally that means HTML. But the headers suggest it is plain text.
Also, I see that Steve replied with a correctly formatted inclusion.
Did anyone else get the scrambled version?
And does anyone have any clues why I did?
(Using Thunderbird v31.8 and normally not having major issues.)
Same here, using Gmail and usually pretty happy with it.

Completely off-topic: why such an old version of TBird? I have some
clients (the local office of a large multinational) who need to communicate
with corporate... but corporate IT hasn't dropped SSL 3.0 yet, so they
can't upgrade past version 33. (Every couple of weeks, despite my repeated
attempts to stop TBird from auto-updating, I find that they've got a new
version and can't connect. Fortunately Mozilla hasn't changed their DB
format, so I can just re-install 33.) Anyway, I know why _they_ are using
an old, less-secure version, but I'm curious why anybody else would be.
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[Emile van Sebille]

Post by Marc Tompkins
(Every couple of weeks, despite my repeated
attempts to stop TBird from auto-updating, I find that they've got a new
version and can't connect. Fortunately Mozilla hasn't changed their DB
format, so I can just re-install 33.) Anyway, I know why _they_ are using
an old, less-secure version, but I'm curious why anybody else would be.

We're stuck on 29 due to some ECMAScript compatibility issues with
existing internal servers. We keep users from upgrading by configuring
all user workstations to update only from an internal server where we
have only approved compatible sources/packages.

Emile



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[Marc Tompkins]

Post by Emile van Sebille

Post by Marc Tompkins
(Every couple of weeks, despite my repeated
attempts to stop TBird from auto-updating, I find that they've got a new
version and can't connect. Fortunately Mozilla hasn't changed their DB
format, so I can just re-install 33.) Anyway, I know why _they_ are using
an old, less-secure version, but I'm curious why anybody else would be.

We're stuck on 29 due to some ECMAScript compatibility issues with
existing internal servers.

Interesting. There are eight million stories in the naked city; I wonder
how many stories there are behind old software versions? =D

Post by Emile van Sebille
We keep users from upgrading by configuring all user workstations to
update only from an internal server where we have only approved compatible
sources/packages.
I only dream of having that sort of control. Ah well.

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[Alan Gauld]

Post by Alan Gauld

Post by Michelle Meiduo Wu
Hi there,
I'm trying to use List in a function. But it doesn't work. Here are
sample code not work: ---------------------------------------def

As you can (hopefully!) see above, this message is completely scrambled.

OK, Looks like I wasn't alone.

Steven,
if you are still reading this can you confirm whether
you got a formatted version or manually unscrambled it?

Or can anyone explain why an apparently plain-text
message got mangled?
--
Alan G
Author of the Learn to Program web site
http://www.alan-g.me.uk/
http://www.amazon.com/author/alan_gauld
Follow my photo-blog on Flickr at:
http://www.flickr.com/photos/alangauldphotos


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[Laura Creighton]

Post by Alan Gauld

Post by Alan Gauld

Post by Michelle Meiduo Wu
Hi there,
I'm trying to use List in a function. But it doesn't work. Here are
sample code not work: ---------------------------------------def

As you can (hopefully!) see above, this message is completely scrambled.

OK, Looks like I wasn't alone.
Steven,
if you are still reading this can you confirm whether
you got a formatted version or manually unscrambled it?
Or can anyone explain why an apparently plain-text
message got mangled?

Her mailer appears to have sent out a plain text message where the
whole message was one line with no newlines/returns. So if her
mailer is set up to automatically remove them ...

Forums do this often but this is the first time I can recall seeing
this in email.

Laura

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[Mark Lawrence]

Post by Alan Gauld

Post by Michelle Meiduo Wu
Hi there,
I'm trying to use List in a function. But it doesn't work. Here are
sample code not work: ---------------------------------------def
getResult(): ls = [] ls= ls.append(100) ls=
ls.append(200) return ls
reList = []reList = getResult()lsLength = len(reList)print '\n The
length of the list is:' +
str(lsLength)-----------------------------------------I ran the above
code, there is an error message: AttributeError: 'NoneType' object has
no attribute 'append'
But the code below not using list in a function
works.----------------------------------------------### This works:ls
= []ls.append(100)ls.append(200)lsLength = len(ls)print '\n list
length is: ' +
str(lsLength)----------------------------------------------------- Do
you know the reason?
Thank you,Michelle

As you can (hopefully!) see above, this message is completely scrambled.
Normally that means HTML. But the headers suggest it is plain text.
Also, I see that Steve replied with a correctly formatted inclusion.
Did anyone else get the scrambled version?
And does anyone have any clues why I did?
(Using Thunderbird v31.8 and normally not having major issues.)

Scrambled using Thunderbird 38.2.0 on Windows 10.
--
My fellow Pythonistas, ask not what our language can do for you, ask
what you can do for our language.

Mark Lawrence

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[D Wyatt]

Scrambled on gmail here too.
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[Mark Lawrence]

Post by D Wyatt
Scrambled on gmail here too.

Please provide some context when you reply, thanks.
--
My fellow Pythonistas, ask not what our language can do for you, ask
what you can do for our language.

Mark Lawrence

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