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Groups > comp.lang.python > #35355

Re: [Help] [Newbie] Require help migrating from Perl to Python 2.7 (namespaces)

From Peter Otten <__peter__@web.de>
Subject Re: [Help] [Newbie] Require help migrating from Perl to Python 2.7 (namespaces)
Date 2012-12-22 12:43 +0100
Organization None
References <ab077ea4-2cfd-4769-afa7-b0cd0045e2d6@googlegroups.com>
Newsgroups comp.lang.python
Message-ID <mailman.1194.1356176640.29569.python-list@python.org> (permalink)

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prilisauer@googlemail.com wrote:

> Hello, to all,
> 
> I hope I can describe me problem correctly.
> 
> I have written a Project split up to one Main.py and different modules
> which are loaded using import and here is also my problem:
> 
> 1. Main.py executes:
> 2. Import modules
> 3. One of the Modules is a SqliteDB datastore.
> 4. A second module creates an IPC socket.
> 5. Here is now my problem :
>     The IPC Socket should run a sub which is stored ad SqliteDB and
>     returns all Rows.
> 
> Is there a elegant way to solve it? except a Queue. Is it possible to
> import modules multiple?! 

If you import a module more than once code on the module level will be 
executed the first time only. Subsequent imports will find the ready-to-use 
module object in a cache (sys.modules).

> I'm unsure because the open DB file at another
> module.
> 
> How is this solved in bigger projects?

If I'm understanding you correctly you have code on the module level that 
creates a socket or opens a database. Don't do that!
Put the code into functions instead. That will give the flexibility you need 
for all sizes of projects. For instance

socket_stuff.py

def send_to_socket(rows):
    socket = ... # open socket
    for row in rows:
        # do whatever it takes to serialize the row
    socket.close()

database_stuff.py

def read_table(dbname, tablename):
    if table not in allowed_table_names:
        raise ValueError
    db = sqlite3.connect(dbname)
    cursor = db.cursor()
    for row in cursor.execute("select * from %s" % tablename):
        yield row
    db.close()


main.py

import socket_stuff
import database_stuff

if __name__ == "__main__":
    socket_stuff.send_to_socket(
        database_stuff.read_table("some_db", "some_table"))

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[Help] [Newbie] Require help migrating from Perl to Python 2.7 (namespaces) prilisauer@googlemail.com - 2012-12-22 02:59 -0800
  Re: [Help] [Newbie] Require help migrating from Perl to Python 2.7 (namespaces) Peter Otten <__peter__@web.de> - 2012-12-22 12:43 +0100
    Re: [Help] [Newbie] Require help migrating from Perl to Python 2.7 (namespaces) prilisauer@googlemail.com - 2012-12-22 04:38 -0800
      Re: [Help] [Newbie] Require help migrating from Perl to Python 2.7 (namespaces) Peter Otten <__peter__@web.de> - 2012-12-22 14:54 +0100
        Re: [Help] [Newbie] Require help migrating from Perl to Python 2.7 (namespaces) prilisauer@googlemail.com - 2012-12-22 08:36 -0800
        Re: [Help] [Newbie] Require help migrating from Perl to Python 2.7 (namespaces) prilisauer@googlemail.com - 2012-12-22 08:36 -0800
    Re: [Help] [Newbie] Require help migrating from Perl to Python 2.7 (namespaces) prilisauer@googlemail.com - 2012-12-22 04:38 -0800
      Re: [Help] [Newbie] Require help migrating from Perl to Python 2.7 (namespaces) prilisauer@googlemail.com - 2012-12-22 04:45 -0800
        Re: [Help] [Newbie] Require help migrating from Perl to Python 2.7 (namespaces) Terry Reedy <tjreedy@udel.edu> - 2012-12-22 16:30 -0500
      Re: [Help] [Newbie] Require help migrating from Perl to Python 2.7 (namespaces) prilisauer@googlemail.com - 2012-12-22 04:45 -0800
        Re: [Help] [Newbie] Require help migrating from Perl to Python 2.7 (namespaces) Alexander Blinne <news@blinne.net> - 2012-12-22 18:26 +0100
          Re: [Help] [Newbie] Require help migrating from Perl to Python 2.7 (namespaces) prilisauer@googlemail.com - 2012-12-22 10:10 -0800
            Re: [Help] [Newbie] Require help migrating from Perl to Python 2.7 (namespaces) Alexander Blinne <news@blinne.net> - 2012-12-22 20:29 +0100
              Re: [Help] [Newbie] Require help migrating from Perl to Python 2.7 (namespaces) prilisauer@googlemail.com - 2012-12-22 12:43 -0800
                Re: [Help] [Newbie] Require help migrating from Perl to Python 2.7 (namespaces) Alexander Blinne <news@blinne.net> - 2012-12-22 22:59 +0100
                Re: [Help] [Newbie] Require help migrating from Perl to Python 2.7 (namespaces) prilisauer@googlemail.com - 2012-12-23 01:32 -0800
                Re: [Help] [Newbie] Require help migrating from Perl to Python 2.7 (namespaces) Terry Reedy <tjreedy@udel.edu> - 2012-12-23 20:53 -0500
                Re: [Help] [Newbie] Require help migrating from Perl to Python 2.7 (namespaces) Alexander Blinne <news@blinne.net> - 2012-12-24 14:10 +0100
                Re: [Help] [Newbie] Require help migrating from Perl to Python 2.7 (namespaces) Dave Angel <d@davea.name> - 2012-12-22 17:03 -0500
                Re: [Help] [Newbie] Require help migrating from Perl to Python 2.7 (namespaces) Cameron Simpson <cs@zip.com.au> - 2012-12-23 21:55 +1100
                Re: [Help] [Newbie] Require help migrating from Perl to Python 2.7 (namespaces) prilisauer@googlemail.com - 2012-12-23 12:59 -0800
                Re: [Help] [Newbie] Require help migrating from Perl to Python 2.7 (namespaces) Peter Otten <__peter__@web.de> - 2012-12-23 22:14 +0100
                Re: [Help] [Newbie] Require help migrating from Perl to Python 2.7 (namespaces) prilisauer@googlemail.com - 2012-12-23 12:59 -0800
                Re: [Help] [Newbie] Require help migrating from Perl to Python 2.7 (namespaces) Roy Smith <roy@panix.com> - 2012-12-23 16:15 -0500
                Re: [Help] [Newbie] Require help migrating from Perl to Python 2.7 (namespaces) prilisauer@googlemail.com - 2012-12-23 13:42 -0800
                Re: [Help] [Newbie] Require help migrating from Perl to Python 2.7 (namespaces) "Rhodri James" <rhodri@wildebst.demon.co.uk> - 2012-12-23 23:38 +0000
                Re: [Help] [Newbie] Require help migrating from Perl to Python 2.7 (namespaces) Dennis Lee Bieber <wlfraed@ix.netcom.com> - 2012-12-24 00:01 -0500
                Re: [Help] [Newbie] Require help migrating from Perl to Python 2.7 (namespaces) Thomas Bach <thbach@students.uni-mainz.de> - 2012-12-24 06:18 +0100
                Re: [Help] [Newbie] Require help migrating from Perl to Python 2.7 (namespaces) Dave Angel <d@davea.name> - 2012-12-24 00:19 -0500
                Re: [Help] [Newbie] Require help migrating from Perl to Python 2.7 (namespaces) prilisauer@googlemail.com - 2012-12-24 00:23 -0800
                Re: [Help] [Newbie] Require help migrating from Perl to Python 2.7 (namespaces) Cameron Simpson <cs@zip.com.au> - 2012-12-24 21:32 +1100
                Re: [Help] [Newbie] Require help migrating from Perl to Python 2.7 (namespaces) Dave Angel <d@davea.name> - 2012-12-24 10:48 -0500
                Re: [Newbie] Require help migrating from Perl to Python 2.7 (namespaces) Ranting Rick <rantingrickjohnson@gmail.com> - 2012-12-24 21:10 -0800
                Re: [Newbie] Require help migrating from Perl to Python 2.7 (namespaces) prilisauer@googlemail.com - 2012-12-25 04:55 -0800
                Re: [Newbie] Require help migrating from Perl to Python 2.7 (namespaces) Dennis Lee Bieber <wlfraed@ix.netcom.com> - 2012-12-25 16:04 -0500
                Re: [Help] [Newbie] Require help migrating from Perl to Python 2.7 (namespaces) Dave Angel <d@davea.name> - 2012-12-24 11:47 -0500
                Re: [Help] [Newbie] Require help migrating from Perl to Python 2.7 (namespaces) Dave Angel <d@davea.name> - 2012-12-24 18:09 -0500
                Re: [Help] [Newbie] Require help migrating from Perl to Python 2.7 (namespaces) prilisauer@googlemail.com - 2012-12-24 00:23 -0800
                Re: [Help] [Newbie] Require help migrating from Perl to Python 2.7 (namespaces) Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2012-12-25 13:44 +0000
                Re: [Help] [Newbie] Require help migrating from Perl to Python 2.7 (namespaces) prilisauer@googlemail.com - 2012-12-25 06:41 -0800
                Re: [Help] [Newbie] Require help migrating from Perl to Python 2.7 (namespaces) Dave Angel <d@davea.name> - 2012-12-25 12:10 -0500
                Re: [Help] [Newbie] Require help migrating from Perl to Python 2.7 (namespaces) prilisauer@googlemail.com - 2012-12-25 09:31 -0800
                Re: [Help] [Newbie] Require help migrating from Perl to Python 2.7 (namespaces) prilisauer@googlemail.com - 2012-12-25 09:31 -0800
                Re: [Help] [Newbie] Require help migrating from Perl to Python 2.7 (namespaces) Rick Johnson <rantingrickjohnson@gmail.com> - 2012-12-25 12:16 -0800
                Re: [Help] [Newbie] Require help migrating from Perl to Python 2.7 (namespaces) Dennis Lee Bieber <wlfraed@ix.netcom.com> - 2012-12-25 16:08 -0500
                Re: [Help] [Newbie] Require help migrating from Perl to Python 2.7 (namespaces) Rick Johnson <rantingrickjohnson@gmail.com> - 2012-12-25 15:42 -0800
                Re: [Help] [Newbie] Require help migrating from Perl to Python 2.7 (namespaces) Michael Torrie <torriem@gmail.com> - 2012-12-26 12:20 -0700
                Re: [Help] [Newbie] Require help migrating from Perl to Python 2.7 (namespaces) Michael Torrie <torriem@gmail.com> - 2012-12-26 11:58 -0700
                Re: [Help] [Newbie] Require help migrating from Perl to Python 2.7 (namespaces) Rick Johnson <rantingrickjohnson@gmail.com> - 2012-12-25 15:42 -0800
                Re: [Newbie] Require help migrating from Perl to Python 2.7 (namespaces) alex23 <wuwei23@gmail.com> - 2012-12-25 19:18 -0800
                Re: [Help] [Newbie] Require help migrating from Perl to Python 2.7 (namespaces) Rick Johnson <rantingrickjohnson@gmail.com> - 2012-12-25 12:16 -0800
                Re: [Help] [Newbie] Require help migrating from Perl to Python 2.7 (namespaces) Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2012-12-25 22:56 +0000
                Re: [Help] [Newbie] Require help migrating from Perl to Python 2.7 (namespaces) Rick Johnson <rantingrickjohnson@gmail.com> - 2012-12-25 16:19 -0800
                Re: [Help] [Newbie] Require help migrating from Perl to Python 2.7 (namespaces) Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2012-12-26 08:29 +0000
                Re: [Help] [Newbie] Require help migrating from Perl to Python 2.7 (namespaces) Rick Johnson <rantingrickjohnson@gmail.com> - 2012-12-26 20:07 -0800
                Re: [Help] [Newbie] Require help migrating from Perl to Python 2.7 (namespaces) Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2012-12-27 05:02 +0000
                Re: [Newbie] Require help migrating from Perl to Python 2.7 (namespaces) Ranting Rick <rantingrickjohnson@gmail.com> - 2012-12-26 22:50 -0800
                Re: [Newbie] Require help migrating from Perl to Python 2.7 (namespaces) Chris Angelico <rosuav@gmail.com> - 2012-12-27 23:58 +1100
                Re: Require help migrating from Perl to Python 2.7 (namespaces) alex23 <wuwei23@gmail.com> - 2012-12-27 05:25 -0800
  Re: [Help] [Newbie] Require help migrating from Perl to Python 2.7 (namespaces) prilisauer@googlemail.com - 2012-12-23 01:36 -0800

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