[Tutor] Buttons

[Alan Gauld]

> I have a cash program that I am trying to create
> buttons for instead of a simple number menu. I
> understand that I need to import the Tkinter, create
> and position the widgets, and enter the main loop

Yes, but of course you aren't doing any of that here...

> (Python in a nut shell). But I am still having
> problems. I have attached the code 

It would help if you gave us a clue as to what the 
problems were? They obviously are not related to the 
Buttons since there is no Tkinter code here.

I'll try to add some comments....
> class AccountTransaction(object):
>     def __init__(self, amount, time):
>         self.amount = amount
>         self.time = time

Not sure why you are using a new style class here, 
especially given that you use old stuyle classes later on.
But it shouldn't cause any real problems.

>     def __repr__(self):
>         description = time.ctime(self.time) + ' '
>         if self.amount < 0:
>             description += '-'
>             description += '$' + str(abs(self.amount))
>             return description

This would be much easier with a format string, something like:

          description += "%s$%05.2s" % (sign, self.amount)

Set the sign using the code above or the simpler(IMHO!):

          sign = (sign < 0 and '-') or ''

>     def __init__(self, initial):
>          self.balance = amount


Not sure why we have two init methods? This will replace the 
first one. If you come from Java or C++ maybe you are used 
to multiple constructors but you can't do that in Python, sorry.

> while 1:
>     print
>     print
>     print 'Show Me The Money'
>     print '1. Deposite'
>     print '2. Withdraw'
>     print '3. Getbalance'
>     print '9. Quit'
>     print
>     choice = int(raw_input('Enter your choice: '))


Lots of print statements are usually better done with a triple 
quoted string and/or a format string. In this case:

     print '''
     
     Show Me The Money
     1. Deposit
     2. Withdraw
     3. Getbalance
     9. Quit

'''
     

> #   I added the exception line so that negartive
> numbers woudl not be added.
> 
>     if choice == 1:
>         amount = raw_input ('Amount: ')
>     elif amount < 0:
>         raise ValueError, 'Deposites must be positive'

This only gets called if choice is not 1. That is it will not 
check the value input by the user. Even if it did you would 
be comparing a string and a number, you need to convert the 
raw_input() value to an int.

>     elif self.balance - amount < 0:

Again, this only gets called if choice is not 1 and amount 
is positive. I suspect you want these tests all to be plain 
if statements nested under the if choice === 1?.

>         date = raw_input ('Date: ')
>         numbers[amount] = date

If you are storing a date why not convert it to a date 
and store that? Its probably easier to manipulate later.
There is a third party date module (mxdate?) that you might 
find easier to use that the standard time module.

>     elif choice == 2:
>         amount = raw_input ('Amount: ')
>     if amount < 0:
>         raise ValueError, 'Withdrawals must be

This will mostly work as you expect, but mainly by accident.
If none of the tests above are true then you will do the choice 
test, then because the elif chain is stopped ypu will do the 
'if amount' test

I suspect the structure you really want is:

if choice == 1:
    # get the amount
    # if amount < 0 : raise error
    # elif balance-amount < 0 : raise error
elif choice == 2:
    # get amount
    # if amount < 0: raise error
    # etc
elif choice == 3:
    # and so on.
elif choice == 9:
    # and here
else: 
    # finally...

> class Account:
>      def Deposit(self, amt):
>          self.balance = self.balance + amt
>      def Withdraw(self,amt):
>          self.balance = self.balance - amt
>      def getbalance(self):
>          return self.balance

You never set balance(no init method?) so any attempt to call
the methods will fail because self.balance has not been 
defined before use.

HTH,

Alan G
Author of the Learn to Program web tutor
http://www.freenetpages.co.uk/hp/alan.gauld