[Tutor] names and variables
I have an object called "myObject" with an attribute called "colour". If I type: print myObject.colour then python prints: red Now, I have a variable "myAttribute" and set its value to "colour" by typing: myAttribute = "colour" I want to have a line of code: something like this: print myObject.myAttribute and have Python interpret it as meaning "print myObject.colour" and hence print "red" Can this be done? If so, how? Jim Morcombe ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] names and variables
On Wed, Aug 20, 2008 at 2:30 AM, Jim Morcombe <[EMAIL PROTECTED]>wrote: > I have an object called "myObject" with an attribute called "colour". > > If I type: > print myObject.colour > then python prints: >red > > Now, I have a variable "myAttribute" and set its value to "colour" by > typing: > myAttribute = "colour" > > I want to have a line of code: something like this: > print myObject.myAttribute > and have Python interpret it as meaning "print myObject.colour" and hence > print "red" > > > Can this be done? If so, how? > > Jim Morcombe > print(getattr(myObject, "colour")) Here's the effbot article: http://effbot.org/zone/python-getattr.htm -- www.fsrtechnologies.com ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] names and variables
On Wed, 2008-08-20 at 11:37 +0200, [EMAIL PROTECTED] wrote: > Message: 7 > Date: Wed, 20 Aug 2008 17:30:37 +0800 > From: Jim Morcombe <[EMAIL PROTECTED]> > Subject: [Tutor] names and variables > To: tutor@python.org > Message-ID: <[EMAIL PROTECTED]> > Content-Type: text/plain; charset=ISO-8859-1; format=flowed > > I have an object called "myObject" with an attribute called "colour". > > If I type: > print myObject.colour > then python prints: > red > > Now, I have a variable "myAttribute" and set its value to "colour" by > typing: > myAttribute = "colour" > > I want to have a line of code: something like this: > print myObject.myAttribute > and have Python interpret it as meaning "print myObject.colour" and > hence print "red" > > > Can this be done? If so, how? > Do you mean this: >>> class A(object): pass ... >>> class A(object): ... colour = 'red' ... >>> a = A() >>> def getcolour(self): ... print self.colour >>> A.myAttribute = getcolour >>> a.myAttribute() 'red' Of course, this is why python's is called dynamic language: the ability to change a class' definition on runtime, even on an already instantiated objects. ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] names and variables
On Wed, Aug 20, 2008 at 5:37 AM, Marc Tompkins <[EMAIL PROTECTED]> wrote: > print(getattr(myObject, "colour")) Or, of course, print getattr(myObject, myAttribute) which is what the OP wanted. Kent ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] Is this a "Class" problem?
I'm assuming you do that so that you don't confuse what a Python built-in method (or function) is, compared to methods (or functions) that you've authored. It's done more to distinguish classes from methods and attributes. I can't claim any credit though. It's part of the python coding conventions in PEP-8. You can find the document at http://www.python.org/dev/peps/pep-0008 . The actual coding convention for attribute and variable names is lower_case_separated_by_underscores, but there are projects out there that use initialLowerCamelCase. Pick whatever your current project is using and stick with it. -jeff___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
[Tutor] named pipe problem
Hi All,
I am trying to get a named pipe working, I have already made a fifo
[EMAIL PROTECTED]:/usr/local/bin$ ls -al /home/dave/kmotion2/www/pipe_func
prw-rw 1 dave www-data 0 2008-08-20 20:25 /home/dave/kmotion2/www/pipe_func
[EMAIL PROTECTED]:/usr/local/bin$
but when I execute my test code to add an item to the fifo ...
func = '199'
www_dir = '/home/dave/kmotion2/www'
print '%s/pipe_func' % www_dir
pipeout = os.open('%s/pipe_func' % www_dir, os.O_WRONLY)
print 'xxx'
os.write(pipeout, func)
os.close(pipeout)
I get the path printed out & then the script hangs silently on pipeout
= os.open('%s/pipe_func' % www_dir, os.O_WRONLY)
Can anyone tell me why ? I expected it to return immediately
Cheers
Dave
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[Tutor] Reformatting phone number
I have a small script (linux) that takes a phone number as an argument: #!/usr/bin/env python import sys number = '+' + sys.argv[1] However, if the first digit of the phone number is a 0 then I need to replace that 0 with "972". I can add the "972", but how do I remove the leading "0"? For instance, this code: #!/usr/bin/env python import sys if sys.argv[1][0] == 0: number = '+972' + sys.argv[1] else: number = '+' + sys.argv[1] Turns the phone number "0123" into "9720123" but I need "972123". How is this done? Better yet, where in the fine manual would I find this? Thanks in advance. -- Dotan Cohen http://what-is-what.com http://gibberish.co.il א-ב-ג-ד-ה-ו-ז-ח-ט-י-ך-כ-ל-ם-מ-ן-נ-ס-ע-ף-פ-ץ-צ-ק-ר-ש-ת ä-ö-ü-ß-Ä-Ö-Ü ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] named pipe problem
On Wed, Aug 20, 2008 at 3:54 PM, dave selby <[EMAIL PROTECTED]> wrote:
> Hi All,
>
>
> I am trying to get a named pipe working, I have already made a fifo
>
> [EMAIL PROTECTED]:/usr/local/bin$ ls -al /home/dave/kmotion2/www/pipe_func
> prw-rw 1 dave www-data 0 2008-08-20 20:25
> /home/dave/kmotion2/www/pipe_func
> [EMAIL PROTECTED]:/usr/local/bin$
>
> but when I execute my test code to add an item to the fifo ...
>
>func = '199'
>www_dir = '/home/dave/kmotion2/www'
>print '%s/pipe_func' % www_dir
>pipeout = os.open('%s/pipe_func' % www_dir, os.O_WRONLY)
>print 'xxx'
>os.write(pipeout, func)
>os.close(pipeout)
>
> I get the path printed out & then the script hangs silently on pipeout
> = os.open('%s/pipe_func' % www_dir, os.O_WRONLY)
>
> Can anyone tell me why ? I expected it to return immediately
See this informative thread:
http://mail.python.org/pipermail/python-list/2006-August/396499.html
Summary: opening a pipe for write blocks until it is also opened for read.
Kent
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Re: [Tutor] Reformatting phone number
I have gotten a bit farther, but I cannot get this to work as described in the previous mail: #!/usr/bin/env python import sys preNumber = sys.argv[1] if preNumber[0] == 0: number = '+972' + preNumber[1:] else: number = '+' + preNumber Where is my flaw? -- Dotan Cohen http://what-is-what.com http://gibberish.co.il א-ב-ג-ד-ה-ו-ז-ח-ט-י-ך-כ-ל-ם-מ-ן-נ-ס-ע-ף-פ-ץ-צ-ק-ר-ש-ת ä-ö-ü-ß-Ä-Ö-Ü ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] Reformatting phone number
I was missing the quotes in the if statement. Changing if preNumber[0] == 0: to if preNumber[0] == "0": fixed the problem. Why did I need those quotes? The 0 is numerical, so it should not need the quotes, no? -- Dotan Cohen http://what-is-what.com http://gibberish.co.il א-ב-ג-ד-ה-ו-ז-ח-ט-י-ך-כ-ל-ם-מ-ן-נ-ס-ע-ף-פ-ץ-צ-ק-ר-ש-ת ä-ö-ü-ß-Ä-Ö-Ü ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] Reformatting phone number
Perhaps because preNumber is a character and not an integer? Robert Dotan Cohen wrote: I was missing the quotes in the if statement. Changing if preNumber[0] == 0: to if preNumber[0] == "0": fixed the problem. Why did I need those quotes? The 0 is numerical, so it should not need the quotes, no? ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] named pipe problem
On Wed, Aug 20, 2008 at 4:53 PM, Kent Johnson <[EMAIL PROTECTED]> wrote:
> See this informative thread:
> http://mail.python.org/pipermail/python-list/2006-August/396499.html
>
> Summary: opening a pipe for write blocks until it is also opened for read.
Also, on Mac OSX at least ordinary file operations seem to work fine.
For example, in one Terminal window:
$ mkfifo testf
$ cat < testf
In another Terminal window, start Python and type
In [5]: f=open('testf', 'w')
In [6]: f.write('foo\n')
In [7]: f.flush()
In [8]: f.close()
The output appears in the first window and the cat command finishes.
If do the Python part first, the open() blocks until I issue the cat
command.
Kent
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Re: [Tutor] Reformatting phone number
2008/8/21 Robert Berman <[EMAIL PROTECTED]>: > Perhaps because preNumber is a character and not an integer? > Perhaps. In php the distinction was made by the fact that there were no non-numerical characters in a string. I don't know enough Python to know if this is the case. Can I declare a variable type in Python as in C? -- Dotan Cohen http://what-is-what.com http://gibberish.co.il א-ב-ג-ד-ה-ו-ז-ח-ט-י-ך-כ-ל-ם-מ-ן-נ-ס-ע-ף-פ-ץ-צ-ק-ר-ש-ת ä-ö-ü-ß-Ä-Ö-Ü ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] Reformatting phone number
Not directly as in C, but, for example, if you have s='3' and you want s used as an integer, you can say s=int(s) and it is an integer. Conversely, if you have a question about the type, you could also say type(s) which, depending, will return, 'str','int', etc. Hope this helps a bit. Robert Dotan Cohen wrote: 2008/8/21 Robert Berman <[EMAIL PROTECTED]>: Perhaps because preNumber is a character and not an integer? Perhaps. In php the distinction was made by the fact that there were no non-numerical characters in a string. I don't know enough Python to know if this is the case. Can I declare a variable type in Python as in C? ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] Reformatting phone number
"Dotan Cohen" <[EMAIL PROTECTED]> wrote know if this is the case. Can I declare a variable type in Python as in C? In Python values have types and variables are simply names associated with values. Thus v = '123'# v 'is' a string because '123' is a string v = 123 # now v 'is' an int because 123 is an int. The variable takes on the type of the value with which it is associated but it can be made to refer to any other value and thus its type effectively changes. So it's best not to think of variables having types but rather consider objects (or values) as having a type, and variables as being associated with objects.. This is one of the most fundamental characteristics of Python and one of the hardest for users of other languages to adapt to. HTH, -- Alan Gauld Author of the Learn to Program web site http://www.freenetpages.co.uk/hp/alan.gauld ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] Reformatting phone number
2008/8/21 Alan Gauld <[EMAIL PROTECTED]>: > "Dotan Cohen" <[EMAIL PROTECTED]> wrote > >> know if this is the case. Can I declare a variable type in Python as >> in C? > > In Python values have types and variables are simply > names associated with values. > > Thus > > v = '123'# v 'is' a string because '123' is a string > v = 123 # now v 'is' an int because 123 is an int. > > The variable takes on the type of the value with which it is > associated but it can be made to refer to any other value > and thus its type effectively changes. So it's best not to > think of variables having types but rather consider objects > (or values) as having a type, and variables as being > associated with objects.. > > This is one of the most fundamental characteristics of > Python and one of the hardest for users of other languages > to adapt to. > This characteristic is similar enough to php (a language where one doesn't even think about types) that I will get used to it. Thanks. -- Dotan Cohen http://what-is-what.com http://gibberish.co.il א-ב-ג-ד-ה-ו-ז-ח-ט-י-ך-כ-ל-ם-מ-ן-נ-ס-ע-ף-פ-ץ-צ-ק-ר-ש-ת ä-ö-ü-ß-Ä-Ö-Ü ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] Reformatting phone number
2008/8/21 Robert Berman <[EMAIL PROTECTED]>: > Not directly as in C, but, for example, if you have s='3' and you want s > used as an integer, you can say s=int(s) and it is an integer. Conversely, > if you have a question about the type, you could also say type(s) which, > depending, will return, 'str','int', etc. > > Hope this helps a bit. > It does help, and I will make a point of familiarizing myself with the errors reported by runtime errors (is this a valid term in Python, as there are no compile errors) such as those generated from code like this: s='hello, world!' s=int(s) -- Dotan Cohen http://what-is-what.com http://gibberish.co.il א-ב-ג-ד-ה-ו-ז-ח-ט-י-ך-כ-ל-ם-מ-ן-נ-ס-ע-ף-פ-ץ-צ-ק-ר-ש-ת ä-ö-ü-ß-Ä-Ö-Ü ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] Reformatting phone number
On Wed, Aug 20, 2008 at 4:43 PM, Dotan Cohen <[EMAIL PROTECTED]> wrote:
> I have a small script (linux) that takes a phone number as an argument:
> #!/usr/bin/env python
> import sys
> number = '+' + sys.argv[1]
>
>
> However, if the first digit of the phone number is a 0 then I need to
> replace that 0 with "972". I can add the "972", but how do I remove
> the leading "0"?
>
> For instance, this code:
> #!/usr/bin/env python
> import sys
> if sys.argv[1][0] == 0:
Another way to write this is
if sys.argv[1].startswith('0'):
>number = '+972' + sys.argv[1]
You need to learn about slicing. This is a way of indexing any
sequence, including strings. See
http://docs.python.org/tut/node5.html#SECTION00512
http://docs.python.org/lib/typesseq.html
In particular, you want
number = '+972' + sys.argv[1][1:]
which takes all characters of argv[0] after the first.
Kent
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[Tutor] programming tic tac toe
Hi. I programmed a simple tic tac toe game in python. I already finished it, but I'm not pleased with the way I used to identify a line. I used a list (with lists inside) to represent the board. And to identify a winning line I used many if's, like this one: def line(board): if board[0][0] == board[1][1] == board[2][2]: return True ... ... return False It's only an examble, but I did it that way. I did not like using all those if's, and I would like to hear suggestions to find a line in the board, maybe a more intelligent approach. I would like a solution using lists because it would be useful for example in C too, but I have been thinking about another way to represent a board. Ark ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] programming tic tac toe
"Ark" <[EMAIL PROTECTED]> wrote I used a list (with lists inside) to represent the board. And to identify a winning line I used many if's, like this one: def line(board): if board[0][0] == board[1][1] == board[2][2]: return True I did not like using all those if's, and I would like to hear suggestions to find a line in the board, maybe a more intelligent approach. Given that there are always 3x3 cells on an oxo board and therefore only 8 possible winning lines hard coding is probably a reasonable approach. You could make it into a single boolean condition which would be slightly less typing and slightly faster but otherwise what you have is fine I think: def line(board): return board[0][0] == board[0][1] == board[0][2] or board[1][0] == board[1][1] == board[1][2] or ... board[2][0] == board[1][1] == board[[0][2] But I'm not sure its that much nicer! :-) For the more general case of an NxN board then you should probably consider using a loop and relative indexing but for 3x3 hard coded is better IMHO. -- Alan Gauld Author of the Learn to Program web site http://www.freenetpages.co.uk/hp/alan.gauld ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] Reformatting phone number
2008/8/21 Kent Johnson <[EMAIL PROTECTED]>:
> Another way to write this is
> if sys.argv[1].startswith('0'):
Nice! I had looked for this type of function, but could not find it.
Is there a list of functions, organized by categories, for Python?
Take for example these pages from te php documentation:
http://il.php.net/manual/en/book.strings.php
http://il.php.net/manual/en/book.array.php
http://il.php.net/manual/en/book.math.php
which are all linked from:
http://il.php.net/manual/en/funcref.php
Is there anything like this for Python? If not, I am willing to code
the site if some Python gurus will help contribute their knowledge.
> You need to learn about slicing. This is a way of indexing any
> sequence, including strings. See
> http://docs.python.org/tut/node5.html#SECTION00512
This I have read, while googling this thread.
> http://docs.python.org/lib/typesseq.html
This I will read, to keep up to speed.
Thanks!
--
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http://what-is-what.com
http://gibberish.co.il
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ä-ö-ü-ß-Ä-Ö-Ü
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Re: [Tutor] Reformatting phone number
2008/8/21 Robert Berman <[EMAIL PROTECTED]>: > One can 'quasi' compile Python code. Since you come from a C background and > I come from a C++ background, a Python compile isn't really compiling an > object module. I don't see an object file, I don't see an executable; > therefore, in my opinion, Python is an interpretive language and I love it. > It is easy to work with. It is incredibly friendly, incredibly powerful, and > it makes building algorithms and shells not only easy but also fun. I really > like this language. The more I learn of it, the more I like it. True, at > times I do miss the speed of C and C++; but I think we tend to ignore the > cost of development time excesses in those languages. I don't have more of a C background than a one-semester course in university. But the details between the languages are night and day. I am enjoying Python. I recently heard that Python is like writing psuedo-code that runs. I am seeing that this is true. I especially love the use of indentation for block demarcation. > To answer your question, I hope. You get errors from the interpretor and > from Python at run time. The interpretor errors tend to be very easy to spot > and to fix; they are primarily indentation or syntax errors. The run time > errors actually show you what failed. You can experiment until you fix them. Error are certainly the best way to learn. > I hope you enjoy using the language as much as I do. Thanks. -- Dotan Cohen http://what-is-what.com http://gibberish.co.il א-ב-ג-ד-ה-ו-ז-ח-ט-י-ך-כ-ל-ם-מ-ן-נ-ס-ע-ף-פ-ץ-צ-ק-ר-ש-ת ä-ö-ü-ß-Ä-Ö-Ü ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
