Re: [Tutor] urllib

[Senthil Kumaran]

On Mon, Dec 07, 2009 at 08:38:24AM +0100, Jojo Mwebaze wrote:
> I need help on something very small...
> 
> i am using urllib to write a query and what i want returned is 'FHI=128%2C128&
> FLO=1%2C1'
> 

The way to use urllib.encode is like this:

>>> urllib.urlencode({"key":"value"})
'key=value'
>>> urllib.urlencode({"key":"value","key2":"value2"})
'key2=value2&key=value'

For your purpses, you need to construct the dict this way:

>>> urllib.urlencode({"FHI":'128,128',"FHO":'1,1'})
'FHO=1%2C1&FHI=128%2C128'
>>> 


And if you are to use variables, one way to do it would be:

>>> x1,y1,x2,y2 = 1,1,128,128
>>> fhi = str(x2) + ',' + str(y2)
>>> fho = str(x1) + ',' + str(y1)
>>> urllib.urlencode({"FHI":fhi,"FHO":fho})
'FHO=1%2C1&FHI=128%2C128'

-- 
Senthil
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Re: [Tutor] urllib

[Jojo Mwebaze]

thanks, Senthil

On Mon, Dec 7, 2009 at 11:10 AM, Senthil Kumaran wrote:

> On Mon, Dec 07, 2009 at 08:38:24AM +0100, Jojo Mwebaze wrote:
> > I need help on something very small...
> >
> > i am using urllib to write a query and what i want returned is
> 'FHI=128%2C128&
> > FLO=1%2C1'
> >
>
> The way to use urllib.encode is like this:
>
> >>> urllib.urlencode({"key":"value"})
> 'key=value'
> >>> urllib.urlencode({"key":"value","key2":"value2"})
> 'key2=value2&key=value'
>
> For your purpses, you need to construct the dict this way:
>
> >>> urllib.urlencode({"FHI":'128,128',"FHO":'1,1'})
> 'FHO=1%2C1&FHI=128%2C128'
> >>>
>
>
> And if you are to use variables, one way to do it would be:
>
> >>> x1,y1,x2,y2 = 1,1,128,128
> >>> fhi = str(x2) + ',' + str(y2)
> >>> fho = str(x1) + ',' + str(y1)
> >>> urllib.urlencode({"FHI":fhi,"FHO":fho})
> 'FHO=1%2C1&FHI=128%2C128'
>
> --
> Senthil
>
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[Tutor] mod_python authentication

[Rayon]

How do I Check for an active login session on every page that requires
authentication

 

Been at this for days and it's holding me back can someone  plz help me with
some code examples. 

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[Tutor] Question : Creating cribbage game

[Christopher schueler]

My name is Chris Schueler and i am having some troubles with my Python 
programming

 

Our current project is to create the game of cribbage from scratch.

The only problem is we are not allowed to use classes, only user-defind 
functions and arrays. I was wondering if anybody could give me tips or pointers 
on adding codes or modifying some of my program

 

Here is my Program so far

I will also include a .py file of it incase this doesnt look legible

 

from random import*

 


def DisplayTitle():
print
print "Welcome to Tech-Sauve Cribbage"
print ""
print "   Insctructions"
print ""
print "1) Only played with two players (for now)   "
print "2) The program starts with a full deck of 52 cards"
print "3) Deals out 6 cards to each player with a Suit letter"
print "4) Then asks each player what 2 cards they want to discard to the 
crib"
print "5) Then the program saves the crib in a temporary deck"
print "6) Players start showing cards to get an ammount equal to 31"
print "7) Once all the cards have been played, program counts the score"
print "8) Then the program will count all possible scores in each hand"
print "   And it will add the players points to their total score"
print "9) First player to reach a score of 121 wins the game"
#Gets players names
def GetPlayer1():
print
Player1 = str(raw_input("Player 1's name "))
return Player1
def GetPlayer2():
print
Player2 = str(raw_input("Player 2's name "))
return Player2
#Building the deck
def Build_Deck():
for R in range (0,52):
cardnumb = numbers[R]
cardsuit = suits[R]
card = str(numbers[R])+str(suits[R])
Deck.append(card)
return Deck,numbers,suits,card,cardnumb,cardsuit


#Variables Needed
numbers = ["A","2","3","4","5","6","7","8","9","10","J","Q","K"]*4
suits = ["H","C","S","D"]*13
suits.sort()
Deck = []
P1hand = []
P2hand = []
Crib = []
Cribcard = []
Cribsuit = []
P1_score = 0
P2_score = 0
Winner = 121
ele = 52
Deck,numbers,suits,card,cardnumb,cardsuit = Build_Deck()
for X in range(0,6):
Y = randint(0,ele)
draw = Deck[Y]
P1hand.append(draw)
Deck.pop(Y)
ele -= 1
for X2 in range (0,6):
Y1 = randint(0,ele)
draw2 = Deck[Y1]
P2hand.append(draw2)
Deck.pop(Y1)
ele -= 1
print
Top = randint(0,47)
Topcard = Deck[Top]
print
for count in range(0,2):
print P1hand
print
option = str(raw_input("Player 1,what CARD would you like to add to the 
crib?  CARDS 1 thru 6 "))
if option == "1":
Crib.append(P1hand[0])
P1hand.pop(0)
elif option == "2":
Crib.append(P1hand[1])
P1hand.pop(1)
elif option == "3":
Crib.append(P1hand[2])
P1hand.pop(2)
elif option == "4":
Crib.append(P1hand[3])
P1hand.pop(3)
elif option == "5":
Crib.append(P1hand[4])
P1hand.pop(4)
elif option == "6":
Crib.append(P1hand[5])
P1hand.pop(5)
print
for c2 in range(0,2):
print P2hand
print
option1 = str(raw_input("Player 2, what CARD would you like to add to the 
crib?  CARDS 1 thru 6 "))
if option1 == "1":
Crib.append(P2hand[0])
P2hand.pop(0)
elif option1 == "2":
Crib.append(P2hand[1])
P2hand.pop(1)
elif option1 == "3":
Crib.append(P2hand[2])
P2hand.pop(2)
elif option1 == "4":
Crib.append(P2hand[3])
P2hand.pop(3)
elif option1 == "5":
Crib.append(P2hand[4])
P2hand.pop(4)
elif option1 == "6":
Crib.append(P2hand[5])
P2hand.pop(5)

print Deck
print "The TOP CARD is ",Topcard
print "Player 1's Hand is ",P1hand
print "Player 2's Hand is ",P2hand
print "The 4 cards in the Crib are ",Crib
  
_
Ready. Set. Get a great deal on Windows 7. See fantastic deals on Windows 7 now
http://go.microsoft.com/?linkid=9691818from random import*

def DisplayTitle():
print
print "Welcome to Tech-Sauve Cribbage"
print ""
print "   Insctructions"
print ""
print "1) Only played with two players (for now)   "
print "2) The program starts with a full deck of 52 cards"
print "3) Deals out 6 cards to each player with a Suit letter"
print "4) Then asks each player what 2 cards they want to discard to the 
crib"
print "5) Then the program saves the crib in a temporary deck"
print "6) Players start showing cards to get an ammount equal to 31"
print "7) Once all the cards have been played, program counts the score"
print "8) Then the program will count all possible scores in each hand"
print "   And it will add the players points to the

Re: [Tutor] mod_python authentication

[Alan Plum]

On Mo, 2009-12-07 at 09:35 -0400, Rayon wrote:
> How do I Check for an active login session on every page that requires
> authentication
>  
> Been at this for days and it’s holding me back can someone  plz help
> me with some code examples.

To understand sessions you first need to understand that HTTP is a
stateless protocol: you connect, send your request, receive a response
and the connection is closed.

Sessions add a layer of abstraction to create functionality the protocol
doesn't provide: multiple requests are grouped and treated as belonging
together.

There are several ways to accomplish this. The most straightforward way
would be remembering the client's IP and persisting variables as
relative to that IP -- problem is, IPs are unreliable, can be faked, and
do not provide a strong indicator of identity (while an IP only resolves
to one machine at a time, that machine may be acting as a gateway or
proxy for multiple users connected from other machines -- also, many IPs
are dynamically allocated thanks to ISPs).

Another method is putting the session's ID in the URLs you display to
your users. This creates a lot of problems, though: the session is only
maintained as long as the user uses exactly the URLs you provide (they
won't stay logged in, for example, if they bookmark a plain URL without
the session ID) and it may accidentally be shared between different
users by passing the URL verbatim (most users don't know enough about
URLs to clean session IDs out of them before sending them to other
people -- or don't care!).

The fix for this is usually to restrict the session to an IP (which is
why you often see the checkbox "Restrict my session to this IP" in
log-in forms), but that screws you over if your IP may randomly change
between consecutive requests and thus may break the illusion.

The most common and reliable choice is the good old session cookie: a
cookie (a small data string) is sent to the browser, containing just the
session ID (and, sometimes, non-critical data such as accessibility
settings if the website provides them). Because the browser is normally
restricted to a single user, the session ID is stored in a safe place --
except it isn't really because some people use e.g. internet cafés and
such which may not dispose of session data regularly. Also, a user may
access the same site from different devices or places, therefore
hoarding cookies for different sessions creating consistency problems.

Still, cookies are the easiest and most reliable way to store a session
ID and non-critical data. If you couple them with IP restrictions and a
conservative expiry time (i.e. duration of inactivity until the session
becomes invalid or "expired" and all associated variables are wiped) and
provide a fallback mechanism for users who disabled (or can't accept)
cookies, you should have most scenarios covered (although some sites
actually just stick to cookies and provide no fallbacks).

So once you've decided on a mechanism to persist the session ID, let's
see what a session actually is. In most cases you want to use them for a
log-in mechanism: the user enters their username and password,
successfully, and is welcomed by a personal greeting and a new
navigation subtree that was previously unavailable.

In this case it may be tempting to simply store the user's ID and log-in
state in a cookie, but that'd be incredibly silly because the user can
easily edit them if he knows about cookies (even worse things can happen
if you provide useful variables like "is_admin: False"). Instead you
should store those variables in a safe place ("persist" them) like a
database or special session files.

The session ID acts as a key to the session file or database entry, so
you need to make sure it's not easily guessable: many websites use very
long seemingly-randomly generated strings (a hash of the user's IP and
the millisecond time of the session's creation may yield good results).

Also, if you want to persist something, make sure it's easily
persistable. A string variable is child's play, an open file on the
other hand may cause locking problems and if you deal with large volumes
of data (e.g. binary file uploads kept in memory) you may quickly run
out of space.

If you don't want to have to deal with all of these considerations and
instead prefer something shrinkwrapped and ready for use, Google is your
friend. Depending on what you use there are plenty of CGI-compatible
packages and WSGI frameworks to choose from.


Cheers,

Alan Plum

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Re: [Tutor] mod_python authentication

[aivars]

Alan,
I am very impressed! This one goes to my knowledge base.
Thanks a lot.

2009/12/7 Alan Plum :
> On Mo, 2009-12-07 at 09:35 -0400, Rayon wrote:
>> How do I Check for an active login session on every page that requires
>> authentication
>>
>> Been at this for days and it’s holding me back can someone  plz help
>> me with some code examples.
>
> To understand sessions you first need to understand that HTTP is a
> stateless protocol: you connect, send your request, receive a response
> and the connection is closed.
>
> Sessions add a layer of abstraction to create functionality the protocol
> doesn't provide: multiple requests are grouped and treated as belonging
> together.
>
> There are several ways to accomplish this. The most straightforward way
> would be remembering the client's IP and persisting variables as
> relative to that IP -- problem is, IPs are unreliable, can be faked, and
> do not provide a strong indicator of identity (while an IP only resolves
> to one machine at a time, that machine may be acting as a gateway or
> proxy for multiple users connected from other machines -- also, many IPs
> are dynamically allocated thanks to ISPs).
>
> Another method is putting the session's ID in the URLs you display to
> your users. This creates a lot of problems, though: the session is only
> maintained as long as the user uses exactly the URLs you provide (they
> won't stay logged in, for example, if they bookmark a plain URL without
> the session ID) and it may accidentally be shared between different
> users by passing the URL verbatim (most users don't know enough about
> URLs to clean session IDs out of them before sending them to other
> people -- or don't care!).
>
> The fix for this is usually to restrict the session to an IP (which is
> why you often see the checkbox "Restrict my session to this IP" in
> log-in forms), but that screws you over if your IP may randomly change
> between consecutive requests and thus may break the illusion.
>
> The most common and reliable choice is the good old session cookie: a
> cookie (a small data string) is sent to the browser, containing just the
> session ID (and, sometimes, non-critical data such as accessibility
> settings if the website provides them). Because the browser is normally
> restricted to a single user, the session ID is stored in a safe place --
> except it isn't really because some people use e.g. internet cafés and
> such which may not dispose of session data regularly. Also, a user may
> access the same site from different devices or places, therefore
> hoarding cookies for different sessions creating consistency problems.
>
> Still, cookies are the easiest and most reliable way to store a session
> ID and non-critical data. If you couple them with IP restrictions and a
> conservative expiry time (i.e. duration of inactivity until the session
> becomes invalid or "expired" and all associated variables are wiped) and
> provide a fallback mechanism for users who disabled (or can't accept)
> cookies, you should have most scenarios covered (although some sites
> actually just stick to cookies and provide no fallbacks).
>
> So once you've decided on a mechanism to persist the session ID, let's
> see what a session actually is. In most cases you want to use them for a
> log-in mechanism: the user enters their username and password,
> successfully, and is welcomed by a personal greeting and a new
> navigation subtree that was previously unavailable.
>
> In this case it may be tempting to simply store the user's ID and log-in
> state in a cookie, but that'd be incredibly silly because the user can
> easily edit them if he knows about cookies (even worse things can happen
> if you provide useful variables like "is_admin: False"). Instead you
> should store those variables in a safe place ("persist" them) like a
> database or special session files.
>
> The session ID acts as a key to the session file or database entry, so
> you need to make sure it's not easily guessable: many websites use very
> long seemingly-randomly generated strings (a hash of the user's IP and
> the millisecond time of the session's creation may yield good results).
>
> Also, if you want to persist something, make sure it's easily
> persistable. A string variable is child's play, an open file on the
> other hand may cause locking problems and if you deal with large volumes
> of data (e.g. binary file uploads kept in memory) you may quickly run
> out of space.
>
> If you don't want to have to deal with all of these considerations and
> instead prefer something shrinkwrapped and ready for use, Google is your
> friend. Depending on what you use there are plenty of CGI-compatible
> packages and WSGI frameworks to choose from.
>
>
> Cheers,
>
> Alan Plum
>
> ___
> Tutor maillist  -  tu...@python.org
> To unsubscribe or change subscription options:
> http://mail.python.org/mailman/listinfo/tutor
>
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Re: [Tutor] Question : Creating cribbage game

[Tim Goddard]

> Message: 2
> Date: Mon, 7 Dec 2009 02:30:30 -0400
> From: Christopher schueler 
> To: 
> Subject: [Tutor] Question : Creating cribbage game
> Message-ID: 
> Content-Type: text/plain; charset="iso-8859-1"
>
>
> My name is Chris Schueler and i am having some troubles with my Python 
> programming
>
>
>
> Our current project is to create the game of cribbage from scratch.
>
> The only problem is we are not allowed to use classes, only user-defind 
> functions and arrays. I was wondering if anybody could give me tips or 
> pointers on adding codes or modifying some of my program
>
>
>
> Here is my Program so far
>
> I will also include a .py file of it incase this doesnt look legible
>
>
>
> from random import*
>
>
>
>
> def DisplayTitle():
>    print
>    print "Welcome to Tech-Sauve Cribbage"
>    print ""
>    print "               Insctructions                "
>    print ""
>    print "1) Only played with two players (for now)   "
>    print "2) The program starts with a full deck of 52 cards"
>    print "3) Deals out 6 cards to each player with a Suit letter"
>    print "4) Then asks each player what 2 cards they want to discard to the 
> crib"
>    print "5) Then the program saves the crib in a temporary deck"
>    print "6) Players start showing cards to get an ammount equal to 31"
>    print "7) Once all the cards have been played, program counts the score"
>    print "8) Then the program will count all possible scores in each hand"
>    print "   And it will add the players points to their total score"
>    print "9) First player to reach a score of 121 wins the game"
> #Gets players names
> def GetPlayer1():
>    print
>    Player1 = str(raw_input("Player 1's name "))
>    return Player1
> def GetPlayer2():
>    print
>    Player2 = str(raw_input("Player 2's name "))
>    return Player2
> #Building the deck
> def Build_Deck():
>    for R in range (0,52):
>        cardnumb = numbers[R]
>        cardsuit = suits[R]
>        card = str(numbers[R])+str(suits[R])
>        Deck.append(card)
>    return Deck,numbers,suits,card,cardnumb,cardsuit
>
>
> #Variables Needed
> numbers = ["A","2","3","4","5","6","7","8","9","10","J","Q","K"]*4
> suits = ["H","C","S","D"]*13
> suits.sort()
> Deck = []
> P1hand = []
> P2hand = []
> Crib = []
> Cribcard = []
> Cribsuit = []
> P1_score = 0
> P2_score = 0
> Winner = 121
> ele = 52
> Deck,numbers,suits,card,cardnumb,cardsuit = Build_Deck()
> for X in range(0,6):
>    Y = randint(0,ele)
>    draw = Deck[Y]
>    P1hand.append(draw)
>    Deck.pop(Y)
>    ele -= 1
> for X2 in range (0,6):
>    Y1 = randint(0,ele)
>    draw2 = Deck[Y1]
>    P2hand.append(draw2)
>    Deck.pop(Y1)
>    ele -= 1
> print
> Top = randint(0,47)
> Topcard = Deck[Top]
> print
> for count in range(0,2):
>    print P1hand
>    print
>    option = str(raw_input("Player 1,what CARD would you like to add to the 
> crib?  CARDS 1 thru 6 "))
>    if option == "1":
>        Crib.append(P1hand[0])
>        P1hand.pop(0)
>    elif option == "2":
>        Crib.append(P1hand[1])
>        P1hand.pop(1)
>    elif option == "3":
>        Crib.append(P1hand[2])
>        P1hand.pop(2)
>    elif option == "4":
>        Crib.append(P1hand[3])
>        P1hand.pop(3)
>    elif option == "5":
>        Crib.append(P1hand[4])
>        P1hand.pop(4)
>    elif option == "6":
>        Crib.append(P1hand[5])
>        P1hand.pop(5)
> print
> for c2 in range(0,2):
>    print P2hand
>    print
>    option1 = str(raw_input("Player 2, what CARD would you like to add to the 
> crib?  CARDS 1 thru 6 "))
>    if option1 == "1":
>        Crib.append(P2hand[0])
>        P2hand.pop(0)
>    elif option1 == "2":
>        Crib.append(P2hand[1])
>        P2hand.pop(1)
>    elif option1 == "3":
>        Crib.append(P2hand[2])
>        P2hand.pop(2)
>    elif option1 == "4":
>        Crib.append(P2hand[3])
>        P2hand.pop(3)
>    elif option1 == "5":
>        Crib.append(P2hand[4])
>        P2hand.pop(4)
>    elif option1 == "6":
>        Crib.append(P2hand[5])
>        P2hand.pop(5)
>
> print Deck
> print "The TOP CARD is ",Topcard
> print "Player 1's Hand is ",P1hand
> print "Player 2's Hand is ",P2hand
> print "The 4 cards in the Crib are ",Crib
>

Unfortunately I had to read a few wiki pages of cribbage first, so my
understanding of the game is weak.



My suggestions:

Start with an outline of play (more to help us understand cribbage)
>From my quick lesson, it sounds like you have so far:

Get player names (two players)
Create deck
Ask player which cards to put in crib

So for what you have now here are some suggestions:

You are creating variables "numbers" and "suits" in your global
namespace.  Then you use them in your Build_Deck function which is
fine, but then you are returning them at the end of the function,
overwriting the original variable definition.  I don't think it would
mess up your code but it is messy.  I also don't see where you

Re: [Tutor] Question : Creating cribbage game

[spir]

Christopher schueler  dixit:

> 
> My name is Chris Schueler and i am having some troubles with my Python 
> programming
> 
>  
> 
> Our current project is to create the game of cribbage from scratch.
> 
> The only problem is we are not allowed to use classes, only user-defind 
> functions and arrays. I was wondering if anybody could give me tips or 
> pointers on adding codes or modifying some of my program


>From my limited experience in coding games. You have to model several distinct 
>aspects:
* Constant data about the game, such as a card set.
* The game logic, mirroring the (real) game rules, ie what players can do, and 
what comes out of their actions.
* The game state, what's the situation at a given point in time, constantly 
modified by the above actions.
* Possibly some AI if the computer plays a role.
Note that first 2 points are predefined aspects (constants in the plain sense 
of the word).

Forbidding OO is a very bad thing because game modelling is precisely a 
programming domain in which this paradigm applies very naturally : every 
element in the game (state) is an "object" that can be modified through methods 
representing game rules.
Python dicts offer a powerful tool to represent kinds of objects, when used as 
records (lookup in wikipedia if you don't see what I mean). Moreover, python 
functions beeing "namable" objects, you can even attach relevant funcs to 
records so as to simulate methods. All you miss then is typical OO syntactic 
sugar where 'self' is automagically inserted as first argument of a method 
call. Instead of
   hand.popCard(card)
you need to write
   hand.popCard(hand, card)

Some more comments below in  your code.

> Here is my Program so far
> 
> I will also include a .py file of it incase this doesnt look legible
> 
>  
> 
> from random import*
> 
>  
> 
> 
> def DisplayTitle():
> print
> print "Welcome to Tech-Sauve Cribbage"
> print ""
> print "   Insctructions"
> print ""
> print "1) Only played with two players (for now)   "
> print "2) The program starts with a full deck of 52 cards"
> print "3) Deals out 6 cards to each player with a Suit letter"
> print "4) Then asks each player what 2 cards they want to discard to the 
> crib"
> print "5) Then the program saves the crib in a temporary deck"
> print "6) Players start showing cards to get an ammount equal to 31"
> print "7) Once all the cards have been played, program counts the score"
> print "8) Then the program will count all possible scores in each hand"
> print "   And it will add the players points to their total score"
> print "9) First player to reach a score of 121 wins the game"

This is a single string to write. Use multiline strings inside triple quotes 
"""...""" and write in a single instruction. No need for a func.

> #Gets players names
> def GetPlayer1():
> print
> Player1 = str(raw_input("Player 1's name "))
> return Player1
> def GetPlayer2():
> print
> Player2 = str(raw_input("Player 2's name "))
> return Player2

This is twice the same func. Write a single one with a parameter representing a 
player, then call it twice. You'd better use a dict for each player because 
doubt the only relevant info is their name. Why not attach their hand, score, 
or whatever to the structures representing players?
player1 = {name:None, more:foo}
player2 = {name:None, more:foo}
def getPlayerName(player):
   # (raw_input already returns a string)
   player["name"] = raw_input("Player 1's name ")
getPlayerName(player1)
getPlayerName(player2)

> #Building the deck
> def Build_Deck():
> for R in range (0,52):
> cardnumb = numbers[R]
> cardsuit = suits[R]
> card = str(numbers[R])+str(suits[R])
> Deck.append(card)
> return Deck,numbers,suits,card,cardnumb,cardsuit

This func should only return Deck. Card cardnum, cardsuit are local variables 
used obly in the func, suits and numbers are input instead:

def Build_Deck(suits, number, card_count):
# 52 is also a predefined constant, namely here called card_count
for R in range (0,card_count):
cardnumb = numbers[R]
cardsuit = suits[R]
card = str(numbers[R])+str(suits[R])
Deck.append(card)
return Deck
... define constants about card: card_count, suits and numbers ...
Deck = Build_Deck(suits, number)

You'd better represent each card with a pair {"suit":suit, "number":number} so 
as to be able to compare their strength (unless this is irrelevant for this 
game).

> #Variables Needed
> numbers = ["A","2","3","4","5","6","7","8","9","10","J","Q","K"]*4
> suits = ["H","C","S","D"]*13
> suits.sort()
> Deck = []
> P1hand = []
> P2hand = []
> Crib = []
> Cribcard = []
> Cribsuit = []
> P1_score = 0
> P2_score = 0
> Winner = 121
> ele = 52

All non-null things above are constants that define 

[Tutor] loops

[Richard Hultgren]

a = 0
b = 1
count = 0
max_count = 20
while count < max_count:
    count = count + 1
    # we need to keep track of a since we change it
    old_a = a# especially here
    old_b = b
    a = old_b
    b = old_a + old_b
    # Notice that the , at the end of a print statement keeps it
    # from switching to a new line
    print old_a,



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Re: [Tutor] loops

[Kent Johnson]

Is there a question here?
Please skip the giant type size.

Kent

On Mon, Dec 7, 2009 at 2:53 PM, Richard Hultgren  wrote:
> a = 0
> b = 1
> count = 0
> max_count = 20
> while count < max_count:
>     count = count + 1
>     # we need to keep track of a since we change it
>     old_a = a# especially here
>     old_b = b
>     a = old_b
>     b = old_a + old_b
>     # Notice that the , at the end of a print statement keeps it
>     # from switching to a new line
>     print old_a,
>
>
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[Tutor] functions--how long is too long?

[Che M]

I have some functions that seem kind of long to me.  One of them, with
white space, comments, print statements, and some commented-out lines,
is 118 lines long.  If I remove all that, it is 57 lines long.  I get the sense
that is inappropriately long for a Python function.  

The length of it is due to a number of if statements--things it needs to
check in terms of the state of the app at the time it is called.  So there
are a number of conditional (and "subconditional") parts to it, and what
it does in response to those conditions.  In fact the word "if" appears in
it 12 times.  

I realize I can and should refactor parts that are used in other places
in the code, but I don't there are that many in some of these.  Is
there a better way to think about organizing this?

Thanks,
Che
  
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Re: [Tutor] functions--how long is too long?

[Luke Paireepinart]

If your code is not sensitive information, it might help us if you post it
to pastebin or something so we can take a look.
In general though, functions should be as long as they need to be (and no
longer!).  57 lines is not inordinately long.  If it's hard for you to read,
though, you should refactor it.

I'd say my personal hard-limit for functions before I start refactoring is
probably around 150-200 lines.  But it's rare that functions get that long
anyway.
Remember to think of them as reusable units of code that do one specific
procedure.  Once you move into OO your functions will probably end up being
rather small as well, that paradigm encourages many small functions
interacting.

On Mon, Dec 7, 2009 at 7:37 PM, Che M  wrote:

>  I have some functions that seem kind of long to me.  One of them, with
> white space, comments, print statements, and some commented-out lines,
> is 118 lines long.  If I remove all that, it is 57 lines long.  I get the
> sense
> that is inappropriately long for a Python function.
>
> The length of it is due to a number of if statements--things it needs to
> check in terms of the state of the app at the time it is called.  So there
> are a number of conditional (and "subconditional") parts to it, and what
> it does in response to those conditions.  In fact the word "if" appears in
> it 12 times.
>
> I realize I can and should refactor parts that are used in other places
> in the code, but I don't there are that many in some of these.  Is
> there a better way to think about organizing this?
>
> Thanks,
> Che
>
> --
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> download.
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Re: [Tutor] functions--how long is too long?

[Kent Johnson]

On Mon, Dec 7, 2009 at 8:37 PM, Che M  wrote:
> I have some functions that seem kind of long to me.  One of them, with
> white space, comments, print statements, and some commented-out lines,
> is 118 lines long.  If I remove all that, it is 57 lines long.  I get the
> sense
> that is inappropriately long for a Python function.
>
> The length of it is due to a number of if statements--things it needs to
> check in terms of the state of the app at the time it is called.  So there
> are a number of conditional (and "subconditional") parts to it, and what
> it does in response to those conditions.  In fact the word "if" appears in
> it 12 times.

Perhaps you can extract some functions from the blocks that make up
the if statements, or move some of the conditionals themselves into
functions. Without seeing some code it is hard to be specific.

Kent
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Re: [Tutor] mod_python authentication

[Marc]

> On Mo, 2009-12-07 at 09:35 -0400, Rayon wrote:
> > How do I Check for an active login session on every page that
> requires
> > authentication
> >
> To understand sessions you first need to understand that HTTP is a
> stateless protocol: you connect, send your request, receive a response
> and the connection is closed.
> 
> There are several ways to accomplish this. The most straightforward way
> would be remembering the client's IP 
> Another method is putting the session's ID in the URLs you display to
> your users. 
> The most common and reliable choice is the good old session cookie

While I agree with the cookie (as long as it has a short expiration),
another way to do this is by using expiring tokenization (credentials + some
unique data for the transaction) in the URL header (see section 14.8 at
http://www.w3.org/Protocols/rfc2616/rfc2616-sec14.html).  Tokenization
substitutes some random string for confidential data (such as credentials).
The payment card industry uses this in the form of an authorization code for
card transactions.  Add to the data represented by the token some unique
data (maybe a random number or some data from the last transaction - it
doesn't matter as the token does not expose the data in any way) for each
http transaction so you have unique token in each header and you can get an
essentially stateful session with a method of checking authentication that
has some spoof protection built in.  Wrap it all in SSL/TLS and then you've
got something.  Granted, this requires some serious server side work, and is
probably not a good beginner exercise, but if this level is what you
need  I have never coded anything like this in Python, but I can see
abstractly how it could be done (I'm a novice with Python). If you're bored,
you can read http://www.shift4.com/pdf/TokenizationWhitePaper.pdf especially
sec1:7.  Ok, Ok, I'll shut up now - I've got to go play with some XML
anyhow...Thanks for listening.





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