473,857 Members | 2,173 Online
Bytes | Software Development & Data Engineering Community
+ Post

Home Posts Topics Members FAQ

Borg vs. Module

I am making a web app, made up of many modules
that all need access to some important data, like
the current session data, cookies, navigation history,
post/get variables, etc.

I decided to go with the 'Borg' idea, by assigning the
__dict__ of an object to a class variable so that each
instantiation of the Borg() would share the same data.
That way I can either pass the Borg around, or just
Borg() it if I need it in some obscure place.

Then I read an argument that it usually makes more sense
to just have a module with the data and functions that
I need, which all the other modules can simply import.
Since I only need one instance, I could just stuff data
and call 'methods' on this module, probably without even
changing existing syntax.

Are there any arguments as to which method is better?

Thanks,

Toby

--
Posted via a free Usenet account from http://www.teranews.com

Jul 31 '06 #1
2 1734

Jordan R McCoy wrote:
For example, the Twisted framework uses this technique to allow global
access to the installed reactor via import syntax, which works well
within the framework. It did, however, throw me a bit when I first
encountered it, and drove me to pour over the source to find out what
was happening.
It sounds to me like this was a case of poor code commenting in Twisted
(Iv'e not looked at it myself). It seems to me this is a useful trick,
but like any unusual or clever bit of coding it's use should be
carefully commented to make sure it's clear to anyone coming across it.

Simon Hibbs

Aug 1 '06 #2
tobiah wrote:
I am making a web app, made up of many modules
that all need access to some important data, like
the current session data, cookies, navigation history,
post/get variables, etc.

I decided to go with the 'Borg' idea, by assigning the
__dict__ of an object to a class variable so that each
instantiation of the Borg() would share the same data.
That way I can either pass the Borg around, or just
Borg() it if I need it in some obscure place.

Then I read an argument that it usually makes more sense
to just have a module with the data and functions that
I need, which all the other modules can simply import.
Since I only need one instance, I could just stuff data
and call 'methods' on this module, probably without even
changing existing syntax.

Are there any arguments as to which method is better?
I would recommend a module over a Borg class simply because it's less
of a hack.

One thing that I never liked about using modules as classes was the
constant need to use the global statement when rebinding any module
level variables. For that reason, if there was a lot of rebinding, I
would rewrite the module as a singleton class. That had its own
problems; most significantly, it was a thorn in my side for
initializing things in the right order. (My current project used lots
of circular imports which made things a lot worse.)

I finally lost my patience and decided to pull that thorn out by
converting the singletons back to modules. That's when I came up with
this little decorator that obviates the need to use global statements,
plus it lets the module look and mostly act like a class.

def modmethod(func) :
class modproxy(object ):
__getattribute_ _ = func.func_globa ls.__getitem__
__setattr__ = func.func_globa ls.__setitem__
self = modproxy()
def call_with_metho d(*args,**kwarg s):
return func(self,*args ,**kwargs)
call_with_metho d.func_name = func.func_name
return call_with_metho d

This decorator means the function will get called with the module
(actually a proxy) as the first argument. That way, you can access
module-level variable exactly like you would access instance variables
in a class, i.e., via self.

I was able to convert all my singletons to modules simply by dedenting
one level, and prefixing all the methods with @modmethod. This worked
so sweetly it this is now my slam dunk recommendation for implementing
a "global singleton" class.
Carl Banks

Aug 1 '06 #3

This thread has been closed and replies have been disabled. Please start a new discussion.

Similar topics

2
2746
by: Rajarshi Guha | last post by:
Hi, I'm having a little problem with understanding the working of a singleton and borg class. Basically I nedd an class whose state will be shared across several modules. I found the stuff on the ASPN cookbook but it does'nt seem to be working for me. I've included some code: Borg.py: -------- class Borg: __shared_state = {} def __init__(self):
10
1535
by: =?iso-8859-1?B?QW5kcuk=?= | last post by:
In my application, I make use of the Borg idiom, invented by Alex Martelli. class Borg(object): '''Borg Idiom, from the Python Cookbook, 2nd Edition, p:273 Derive a class form this; all instances of that class will share the same state, provided that they don't override __new__; otherwise, remember to use Borg.__new__ within the overriden class.
2
1391
by: Tobiah | last post by:
I have a class that I call Borg that starts like this: class Borg(dict): static_state = {} def __init__(self): self.__dict__ = self.static_state so that I can access the same data from anywhere within
1
1111
by: seanacais | last post by:
I want to create a class derived from a Borg class that can instantiated as part of a script or be contained in other classes. When methods from the Borg class are called, I would like to know the name of the class that contains the Borg class. I've played a bit with inspect and _getframe from the sys module but get inconsistent results. The main problem is if the Borg class is instantiated outside a containing class, then I need to go...
0
9923
marktang
by: marktang | last post by:
ONU (Optical Network Unit) is one of the key components for providing high-speed Internet services. Its primary function is to act as an endpoint device located at the user's premises. However, people are often confused as to whether an ONU can Work As a Router. In this blog post, we’ll explore What is ONU, What Is Router, ONU & Router’s main usage, and What is the difference between ONU and Router. Let’s take a closer look ! Part I. Meaning of...
0
11082
Oralloy
by: Oralloy | last post by:
Hello folks, I am unable to find appropriate documentation on the type promotion of bit-fields when using the generalised comparison operator "<=>". The problem is that using the GNU compilers, it seems that the internal comparison operator "<=>" tries to promote arguments from unsigned to signed. This is as boiled down as I can make it. Here is my compilation command: g++-12 -std=c++20 -Wnarrowing bit_field.cpp Here is the code in...
0
10711
jinu1996
by: jinu1996 | last post by:
In today's digital age, having a compelling online presence is paramount for businesses aiming to thrive in a competitive landscape. At the heart of this digital strategy lies an intricately woven tapestry of website design and digital marketing. It's not merely about having a website; it's about crafting an immersive digital experience that captivates audiences and drives business growth. The Art of Business Website Design Your website is...
1
10807
by: Hystou | last post by:
Overview: Windows 11 and 10 have less user interface control over operating system update behaviour than previous versions of Windows. In Windows 11 and 10, there is no way to turn off the Windows Update option using the Control Panel or Settings app; it automatically checks for updates and installs any it finds, whether you like it or not. For most users, this new feature is actually very convenient. If you want to control the update process,...
0
9549
agi2029
by: agi2029 | last post by:
Let's talk about the concept of autonomous AI software engineers and no-code agents. These AIs are designed to manage the entire lifecycle of a software development project—planning, coding, testing, and deployment—without human intervention. Imagine an AI that can take a project description, break it down, write the code, debug it, and then launch it, all on its own.... Now, this would greatly impact the work of software developers. The idea...
0
5774
by: TSSRALBI | last post by:
Hello I'm a network technician in training and I need your help. I am currently learning how to create and manage the different types of VPNs and I have a question about LAN-to-LAN VPNs. The last exercise I practiced was to create a LAN-to-LAN VPN between two Pfsense firewalls, by using IPSEC protocols. I succeeded, with both firewalls in the same network. But I'm wondering if it's possible to do the same thing, with 2 Pfsense firewalls...
0
5967
by: adsilva | last post by:
A Windows Forms form does not have the event Unload, like VB6. What one acts like?
1
4592
by: 6302768590 | last post by:
Hai team i want code for transfer the data from one system to another through IP address by using C# our system has to for every 5mins then we have to update the data what the data is updated we have to send another system
2
4190
muto222
by: muto222 | last post by:
How can i add a mobile payment intergratation into php mysql website.

By using Bytes.com and it's services, you agree to our Privacy Policy and Terms of Use.

To disable or enable advertisements and analytics tracking please visit the manage ads & tracking page.