Re: [Tutor] Simple Python Address Book (Advice welcome!)
On 17/06/12 02:45, mariocatch wrote:
I'm essentially asking if someone wouldn't mind taking a look at what I
have so far, and giving some advice on some of my weak areas,
Welcome, I've inserted a few comments below.
In general it's OK although personally I'd probably put the email
validation in a short helper function (including the regex definition
etc) just to tidy it up and avoid one level of indentation. (Its also
potentially reusable so I'd probably put that function in its own module
too...
I'd probably also put all the splitting logic into LoadAddresses so that
what I get back is the actual address dictionary rather than the raw
list of lines.
That would clean up main() quite a bit.
Also it's conventional to make function names start with lowerCase.
UpperCase names usually imply it's a class.
Finally, I'd put all the functions above main() rather than having the
lonely looking RecordAddresses() at the end.
import re # email validation
import textwrap
# forward declarations
addressBookPath = r'C:\temp\addresses.txt'
addressBook = {} # address book held in memory before dumped to file
emailFormatRegex = r'(\w[\w]*)@([\w]+\.[\w]+)'
recordDelimiter = ' | ' # split name | email in file
def LoadAddresses():
""" Loads all addresses from file and places
them in tuple in form (bool, list), where the list is each
row from the file (a person's name | email). """
success, lines = (False, [])
try:
f = open(addressBookPath, 'r')
lines = f.readlines()
f.close()
success, lines = (True, lines)
except IOError as e:
print 'Error opening address book: ', e
return (success, lines)
The latest style preference in Python is to use with statements for file
handling, so that would become:
try:
with f as open(.):
success,lines = True, f.readlines()
except IOError as e:
print ...
return (success,lines)
'with' guarantees file closure automatically.
def main():
(success, lines) = LoadAddresses()
if not success:
shouldMakeNewBook = raw_input(textwrap.fill("""You do not have
an address book yet.
Would you like to
create one?"""))
if shouldMakeNewBook in ('y', 'ye', 'yes'):
f = open(addressBookPath, 'w')
f.close()
print 'New address book created.', addressBookPath
else:
print 'Exiting...'
return
else:
# now that we have the file loaded into memory,
# fill out the addressbook from file
for line in lines:
splitStr = line.split(recordDelimiter)
addressBook[splitStr[0]] = splitStr[-1]
# main input loop (break with 'q' or 'quit' during input)
while True:
newPersonNameInput = raw_input('Enter new person\'s name:
(q/quit to stop):')
if newPersonNameInput.lower() in ('q', 'quit'):
break
addressBook[newPersonNameInput] = newPersonNameInput
while True: # loop until email is in valid format (x@y.z
)
newPersonEmailInput = raw_input('Enter new person\'s email:
(q/quit to stop):')
match = re.search(emailFormatRegex, newPersonEmailInput)
if not match:
print 'email validation failed... try again.'
continue
continue is not strictly needed here, but does make the intent clear.
else:
addressBook[newPersonNameInput] = newPersonEmailInput
break # success
RecordAddresses()
print addressBook
def RecordAddresses():
""" Writes out each address to the file in the form of name |
email. """
f = open(addressBookPath, 'w')
for k, v in sorted(addressBook.items()):
Should have a try in case the file fails to open.
Also slightly more pythonic to do
for k,v in open():
There is no point in sorting the data if you are going to read it into a
dictionary, Python's dictionaries are unsorted. (Unless you plan on
reading the file manually - in a text editor say)
#is there a better way to do this without placing a newline
after each row?
#it's causing multiple line separations when writing back out
to file (because each
# time we finish reading, it ends with a trailing newline).
f.write("{0}{1}{2}\n".format(k, recordDelimiter, v))
Sorry, you have to add a newline when writing to the file and strip it
off when reading. Its just how it is...
--
Alan G
Author of the Learn to Program web site
http://www.alan-g.me.uk/
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Re: [Tutor] Simple Python Address Book (Advice welcome!)
On Sun, 17 Jun 2012, Alan Gauld wrote:
On 17/06/12 02:45, mariocatch wrote:
after each row?
#it's causing multiple line separations when writing back out
to file (because each
# time we finish reading, it ends with a trailing newline).
f.write("{0}{1}{2}\n".format(k, recordDelimiter, v))
Sorry, you have to add a newline when writing to the file and strip it off
when reading. Its just how it is...
If you're using Python3 or from __future__ import print_function, you can do
this
print(k,v, sep=recordDelimiter, file=f)
Which might make things a little cleaner. There's also the end parameter which
defaults to end='\n'
HTH,
Wayne
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[Tutor] Dictionaries
Hello, I am having a problem with a small application I am writing. I have to have the user input the key, then have the program output the value associated with it. A way to inform the user that the key they entered is not in the dictionary or somefing would be nice also. Fank you for your help, -Selby ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] Dictionaries
On 6/17/2012 7:14 AM Selby Rowley-Cannon said... Hello, I am having a problem with a small application I am writing. I have to have the user input the key, then have the program output the value associated with it. A way to inform the user that the key they entered is not in the dictionary or somefing would be nice also. Fank you for your help, -Selby It's easiest for us to help you when you've posted a copy of your code and the resulting traceback information showing the error you're getting. To be complete, include your platform and python version. Then we can provide you the specific help you need to keep you moving forward. You might also want to read the highly regarded article at http://www.catb.org/~esr/faqs/smart-questions.html Emile ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] Dictionaries
Greetings, : I am having a problem with a small application I am writing. I : have to have the user input the key, then have the program output : the value associated with it. A way to inform the user that the : key they entered is not in the dictionary or somefing would be : nice also. I would agree also with Emile--in the future, you will probably get a better answer if you are more specific in your question. This one is a pretty easy question to answer and show you some samples for how to approach this with code snippets. I will assume that userinput is a variable with the contents of interest that your user typed. I will use the variable d to represent some dictionary (any dictionary). if userinput in d: print 'Found', userinput, 'in dictionary, value was', d[userinput] else: print 'No entry' Depending on what else you are doing (besides printing), you might also look into the get() method of dictionaries: default = '' string_to_print = d.get(userinput,default) print 'You typed %s. The entry was %s.' % ( userinput, string_to_print) These are pretty common usage patterns for dictionaries, so you might benefit from looking at the other sorts of things that you can do with dictionaries. Good luck, -Martin -- Martin A. Brown http://linux-ip.net/ ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] Dictionaries
On 17/06/12 15:14, Selby Rowley-Cannon wrote: I am having a problem with a small application I am writing. I have to have the user input the key, then have the program output the value associated with it. A way to inform the user that the key they entered is not in the dictionary or somefing would be nice also. So what's the problem? This sounds a wee bit like a homework assignment and we have a policy of not doing those for you... If you show us what you've done so far, and any errors then you can ask for more specific help. -- Alan G Author of the Learn to Program web site http://www.alan-g.me.uk/ ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor
[Tutor] Dictionary
Version: 2.7
OS: Ubuntu 12.04 LTS
I am writing a small translation app for Rydish (A language that exists in the
same way Klingon does, invented by my company for a[n] RPG).
Here is my current method of translation:
Edictionary = {'English keys':'Rydish values'}
TextEng = raw_input('Please enter your text: ')
if TextEng in Edictionary:
print(TextEng + ' traslates to ' + Edictionary[TextEng])
But I have found that this is only going to translate one word at a time. I
thought about a loop of somesort, but I can't seem to find one that won't still
force the user to translate one word at a time. Can anyone tell me how to
translate a full sentance/several sentances?
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Re: [Tutor] Dictionary
Does this language have grammar independent of english?
If no, just use .split() on the string and loop through that.
If yes, well, its much more complicated
On Jun 17, 2012 2:27 PM, "Selby Rowley-Cannon"
wrote:
> Version: 2.7
> OS: Ubuntu 12.04 LTS
>
> I am writing a small translation app for Rydish (A language that exists in
> the same way Klingon does, invented by my company for a[n] RPG).
> Here is my current method of translation:
>
> Edictionary = {'English keys':'Rydish values'}
> TextEng = raw_input('Please enter your text: ')
> if TextEng in Edictionary:
> print(TextEng + ' traslates to ' + Edictionary[TextEng])
>
> But I have found that this is only going to translate one word at a time.
> I thought about a loop of somesort, but I can't seem to find one that won't
> still force the user to translate one word at a time. Can anyone tell me
> how to translate a full sentance/several sentances?
>
> ___
> Tutor maillist - Tutor@python.org
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>
>
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[Tutor] python varying mulitple inheritance
Hello I'm new to classes. And I hope the my question isn't too big. I have electronic test equipment, but thought that a boat example would be easier. Can you help me untangle my class design? My problem is basically multiple inheritance, but I want to be flexible for how many will inherit. I'll put my example below and also as an attachment. I'm running Python 2.7 on Linux. Python is the BEST! Thanks Ken cut here #!/usr/bin/env python """ Variable Multiple Inheritance. email: ke...@kendy.org A boat has a body and is powered by any combination of Battery and/or Solar and/or Gas or None. If a boat is powered, it should have only one emergency_shutoff. """ class Body: """ A boat has a body """ def __init__(self, length): self.length = length class Power: """ Super Base class If a boat is powered. """ def __init__(self, emergency_shutoff): self.emergency_shutoff = emergency_shutoff def Emergency(): emergency_shutoff = True class Battery(Power): """ sub Child class """ def __init__(self, emergency_shutoff, battery_volt): self.battery_volt = battery_volt Power.__init__(self, emergency_shutoff) def ChargeBattery(): pass class Solar(Power): """ sub Child class """ def __init__(self, emergency_shutoff, solar_volt): self.solar_volt = solar_volt Power.__init__(self, emergency_shutoff) def DoSomethingSolar(): pass class Gasoline(Power): """ sub Child class """ def __init__(self, emergency_shutoff, liters): self.liters = liters Power.__init__(self, emergency_shutoff) class Boat1(Body): """ Sailboat """ pass class Boat2(Body, Gasoline, Battery): """ Gas, with battery backup powered """ def __init__(self, length, emergency_shutoff, liters, battery_volt): Body.__init__(self, length) Power.__init__(self, emergency_shutoff) Gasoline.__init__(self, emergency_shutoff, liters) Battery.__init__(self, emergency_shutoff, battery_volt) class Boat3(Body, Battery, Solar): """ Electric powered """ def __init__(self, length, emergency_shutoff, solar_volt, battery_volt): Body.__init__(self, length) Power.__init__(self, emergency_shutoff) Solar.__init__(self, emergency_shutoff, solar_volt) Battery.__init__(self, emergency_shutoff, battery_volt) def ShowAssembly(assembly_queue): for workon in assembly_queue: pass def main(): """ Acts like a container class""" assembly_queue = [] # A list of boats to be assembled, in order. assembly_queue.append(Boat2(30, False, 'half-full', 50)) assembly_queue.append(Boat3(25, False, 30, 10)) assembly_queue.append(Boat1(20)) ShowAssembly(assembly_queue) if __name__ == '__main__': main() cut here vary_mult_inherit.py Description: Binary data ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] python varying mulitple inheritance
ke...@kendy.org wrote: Hello I'm new to classes. And I hope the my question isn't too big. I have electronic test equipment, but thought that a boat example would be easier. Can you help me untangle my class design? My problem is basically multiple inheritance, but I want to be flexible for how many will inherit. Your first problem is that you are misusing inheritance when you should be using composition instead. Inheritance is for "is-a" relationships. For example: Bob is a Person, so Bob should be an instance of Person class. A Person is a Mammal, so Person should inherit from Mammal class. A Mammal is an Animal, so Mammal should inherit from Animal class. Bob has a wallet, he is not a wallet himself. So the Bob instance should have an attribute "wallet", storing an instance of Wallet class. This is called composition. In your example, you have a Boat class. Boat is pretty generic, so it might be the top-level class. Or it might be a subclass of Vehicle. You might then subclass Boat to give SailingBoat, MotorBoat, SpeedBoat, Battleship, etc. But boats are not kinds of engines, so it is inappropriate for Boat to inherit from Engine. A boat (well, at least some boats) has an engine, so you might do something like this: class Boat: pass class SailBoat(Boat): def __init__(self, sails): self.sails = sails class RowBoat(Boat): def __init__(self, oars): self.oars = oars class PowerBoat(Boat): def __init__(self, engine): self.engine = engine class SpeedBoat(PowerBoat): """A SpeedBoat is a kind of PowerBoat with an outboard motor.""" def __init__(self): super(SpeedBoat, self).__init__(outboard_motor) class Yacht(SailBoat): """A Yacht is a kind of SailBoat.""" # Note that the name Yacht is ambiguous, as it is also used for # a class of small power boats! def __init__(self): super(SailBoat, self).__init__(spinnaker) A boat with both sails and an engine would then use multiple inheritance to inherit from both PowerBoat and SailBoat; it would have both an engine and a sail. Note that when using single-inheritance, you have a choice in how to call the parent classes' method: class K(C): def method(self, arg): result = C.method(self, arg) # Call the parent method directly. process(result) or use super: class K(C): def method(self, arg): result = super(K, self).method(arg) # Let Python find the method. process(result) Either way is fine. BUT once you intend to use multiple inheritance, you MUST use super, or your code risks being buggy. NEVER call a superclass method directly using multiple inheritance, or even if you might someday want to use multiple inheritance. Always use super instead. (Note: in Python 3, you can simplify the call to super to just super() instead of super(K, self). This does not work in Python 2.) Multiple inheritance is quite tricky to get right, which is why many programming languages prohibit it. If you google for "multiple inheritance python" you will find many discussions about it, explaining the pros and cons, difficulties and alternatives. One last thing: you will save yourself a lot of pain in the future if you stick to a consistent convention for naming things. The usual convention used in Python is the classes are named with an initial Capital letter, using so-called "CamelCase" if the name has multiple words. Methods, functions, attributes and instances are named in lowercase, using underscores to separate words: bob_the_builder = Builder(name='Bob'). For more about the suggested (but not compulsory) naming conventions, see this: http://www.python.org/dev/peps/pep-0008/ -- Steven ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor
