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Groups > comp.lang.python > #35358

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

Newsgroups comp.lang.python
Date 2012-12-22 04:38 -0800
References <ab077ea4-2cfd-4769-afa7-b0cd0045e2d6@googlegroups.com> <mailman.1194.1356176640.29569.python-list@python.org>
Subject Re: [Help] [Newbie] Require help migrating from Perl to Python 2.7 (namespaces)
From prilisauer@googlemail.com
Message-ID <mailman.1196.1356179894.29569.python-list@python.org> (permalink)

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Am Samstag, 22. Dezember 2012 12:43:54 UTC+1 schrieb Peter Otten:
>  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"))

Hello Thanks for that answer:
I think I have to write it a bit larger,

This isn't a real code, but it for better overview:
                        main.py
          /        /             \             \
-------------------------------------------------------------------
Datastore  |  ModbusClient  | DaliBusClient | Advanced Scheduler
--------------------------------------------------------------------


Main.py:
import Datastore
Datastore.startup()
....
(Everything should run in threads) 

Datastore.py
# Opens a SQLite DB
# Contains Queries to serve data for other mods
# Central point for updating / Quering etc.

ModbusClient.py
# Opens TCP connection to Modbus Device
!!! Here it's interesting !!!
This module contains predefined Queries and functions
IF I START A FUNCTION a SQL should be executed in Datastore.py


DaliBusClient.py
#Lamps, etc. Functions. 
# Stored Informations should be kept in Datastore
# Advanced scheduler


I don't know, Python allways looks for me like a one script "File". But there are big projects. like the the "Model of an SQL Server", using coordinators no problems running threads and exchange Data through a Backbone. I have searched a lot, but I havent find anything to write the "core" splited up into modules and geting over the scopes etc.

DO I have anything forgotten?! everything unclear?? :-P 

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Thread

[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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