"pickle" vs. f.write()

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  • Johan Kohler
    #1

    "pickle" vs. f.write()

    Hi,

    I have a class with attributes that are string, integer and list. eg.

    class person:
    name =""
    age = 0
    friends=[]
    comment=""""""

    me = person()

    I want to save a whole bunch of instances to a file, a classic "records"
    file I/O.

    To write the file, I can do f.write(str([me.name, me.age, me.friends,
    me.comment]) + "\n"

    This works nicely for writing, but when reading, I cannot convert the
    string easily to a list:
    list(f.readline ()) is not the same as [me.name, me.age, me.friends,
    me.comment]

    I was wondering whether pickle might make this easier - an example would
    be much appreciated.

    Otherwise, what is the best "Python" way to write and read this data
    structure?

    Thanks in advance...

    Johan

    __
    Yes, I do feel stupid asking this, but time's-a-runnin' out..
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    • Peter Maas
      #2
      Re: &quot;pickle&qu ot; vs. f.write()

      Johan Kohler schrieb:[color=blue]
      > class person:
      > name =""
      > age = 0
      > friends=[]
      > comment=""""""
      >
      > me = person()
      >
      > Otherwise, what is the best "Python" way to write and read this data
      > structure?[/color]

      import pickle

      class person:
      name =""
      age = 0
      friends=[]
      comment=""""""

      me = person()

      # store
      pf = file('/tmp/pickletest', 'w')
      pickle.dump(me, pf)
      pf.close()


      # load
      pf = file('/tmp/pickletest', 'r')
      me2 = pickle.load(pf)
      pf.close()

      This is sequential access. If you want to have random access, look
      for shelve.

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      Peter Maas, M+R Infosysteme, D-52070 Aachen, Tel +49-241-93878-0
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        Comment

        • Johan Kohler
          #3
          Re: &quot;pickle&qu ot; vs. f.write()

          Thanks... works like a charm :-)

          On Wed, 26 Jan 2005 12:55:38 +0100, Peter Maas <peter@somewher e.com> wrote:
          [color=blue]
          > Johan Kohler schrieb:[color=green]
          >> class person:
          >> name =""
          >> age = 0
          >> friends=[]
          >> comment=""""""
          >> me = person()
          >> Otherwise, what is the best "Python" way to write and read this data
          >> structure?[/color]
          >
          > import pickle
          >
          > class person:
          > name =""
          > age = 0
          > friends=[]
          > comment=""""""
          >
          > me = person()
          >
          > # store
          > pf = file('/tmp/pickletest', 'w')
          > pickle.dump(me, pf)
          > pf.close()
          >
          >
          > # load
          > pf = file('/tmp/pickletest', 'r')
          > me2 = pickle.load(pf)
          > pf.close()
          >
          > This is sequential access. If you want to have random access, look
          > for shelve.
          >[/color]



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