Am Samstag, 22. Dezember 2012 12:43:54 UTC+1 schrieb Peter Otten:
> wrote:
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>
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> > Hello, to all,
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> >
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> > I hope I can describe me problem correctly.
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> >
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> > I have written a Project split up to one Main.py and different modules
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> > which are loaded using import and here is also my problem:
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> >
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> > 1. Main.py executes:
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> > 2. Import modules
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> > 3. One of the Modules is a SqliteDB datastore.
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> > 4. A second module creates an IPC socket.
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> > 5. Here is now my problem :
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> > The IPC Socket should run a sub which is stored ad SqliteDB and
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> > returns all Rows.
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> >
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> > Is there a elegant way to solve it? except a Queue. Is it possible to
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> > import modules multiple?!
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>
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> If you import a module more than once code on the module level will be
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> executed the first time only. Subsequent imports will find the ready-to-use
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> module object in a cache (sys.modules).
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>
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> > I'm unsure because the open DB file at another
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> > module.
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> >
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> > How is this solved in bigger projects?
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>
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> If I'm understanding you correctly you have code on the module level that
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> creates a socket or opens a database. Don't do that!
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> Put the code into functions instead. That will give the flexibility you need
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> for all sizes of projects. For instance
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>
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> socket_stuff.py
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>
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> def send_to_socket(rows):
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> socket = ... # open socket
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> for row in rows:
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> # do whatever it takes to serialize the row
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> socket.close()
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>
>
> database_stuff.py
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>
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> def read_table(dbname, tablename):
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> if table not in allowed_table_names:
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> raise ValueError
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> db = sqlite3.connect(dbname)
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> cursor = db.cursor()
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> for row in cursor.execute("select * from %s" % tablename):
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> yield row
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> db.close()
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>
>
> main.py
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>
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> import socket_stuff
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> import database_stuff
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>
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> if __name__ == "__main__":
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> socket_stuff.send_to_socket(
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> 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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