[Tutor] Saving and loading data to/from files

[Daryl G]

Yup, it was the global/local problem. I thought that since I had those 
varibles declared globally, they would be scene everywere, but local 
varibles take precedence. Forgot about that

The %s doesn't quite work right. If a name is shorter than another, then the 
positions wont be right in my simple table. I guess I have to see if that 
center() method will work for me.

example
LastName        FirstName       Phone#
Stephanopolis   George          900-856-2992
Jo   Mary          800-328-6387

is what I end up getting.
Thanks. I'll check that api doc

Computer Spreadsheet Vomitus. I love that. :)


>From: "Michael P. Reilly" <arcege@dsl092-074-184.bos1.dsl.speakeasy.net>
>Reply-To: arcege@speakeasy.net
>To: gman_95@hotmail.com (Daryl G)
>CC: tutor@python.org
>Subject: Re: [Tutor] Saving and loading data to/from files
>Date: Sun, 3 Jun 2001 07:52:12 -0400 (EDT)
>
>Daryl G wrote
> >
> > Hi,  I am having difficulty in saving and loading data that I created in 
>a
> > simple Address book program. I  am using 3 list variables for First and 
>Last
> > name and phone number and an interger that counts the total number of
> > entries.  I first tried using the 'write' but that wouldn't work with 
>lists.
> > I discovered the pickle module and
> > I am able to save my data, but when I load it back up and then try to 
>view
> > it in my program, its not there.
> >
> > variables
> > import pickle, string
> >
> > F_Name=[]
> > L_Name=[]
> > PH_num=[]
> > total=0
> >
> > #savedata method
> > def savedata():
> >     filename= raw_input("Enter the name you wish to give this address 
>book:
> > ")
> >     object=(F_Name, L_Name, PH_num, total)
> >     file=open(filename, 'w')
> >     pickle.dump(object, file)
> >
> > #opendata method
> > def opendata():
> >     filename=raw_input("Enter the name of the Addressbook you wish to 
>open:
> > ")
> >     file = open(filename,'r')
> >     (F_Name,L_Name, PH_num, total)=pickle.load(file)
> >
> >
> > What am I doing wrong?
>
>You are assigning to local variables in opendata() when the variables
>are global in savedata.  However you might want to think about passing
>values, especially removing the raw_input() calls from the functions.
>
>def opendata(filename):
>   global F_Name, L_Name, PH_num, total
>   file = open(filename, 'r')
>   (F_Name, L_Name, PH_num, total) = pickle.load(file)
>
>Or better yet, returning the values:
>def opendata(filename):
>   file = open(filename, 'r')
>   # assigning to all values catches the error of invalid data format
>   (F_Name, L_Name, PH_num, total) = pickle.load(file)
>   return (F_Name, L_Name, PH_num, total)
>
>Pickle is fine for outputting single values, but for a database of
>values (like an address) you will want to look at the shelve module
>(which uses pickle and the *dbm modules, see "anydbm") or a relational
>database (which could be overkill for an address book application).
>
> > Another question that I have is how do I format data that I want to 
>display
> > in specific
> > columns in standerd output, like that can be done in C ?
>
>This is done with the string % operator.  With an order sequence:
>   print '''Name: %s %s; Phone: %s''' % (F_Name, L_Name, PH_num)
>or with a dictionary:
>   print '''Name: %(first)s %(last)s; Phone: %(phone)s''' % {
>     'first': F_Name, 'last': L_Name, 'phone': PH_num
>   }
>
>The Python Library documention has all this.  Much of it is actually
>like C's sprintf.
><URL: http://www.python.org/doc/current/lib/typesseq-strings.html>
>
>   -Arcege
>
>--
>+----------------------------------+-----------------------------------+
>| Michael P. Reilly                | arcege@speakeasy.net              |

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