Snipplr

(Python) Name Mangling of Python Private Variables - ishikawa

Mon, 30 Jun 2008 10:08:15 GMT

Python: Private Variables http://docs.python.org/tut/node11.html#SECTION0011600000000000000000 Any identifier of the form __spam (at least two leading underscores, at most one trailing underscore) is textually replaced with _classname__spam, where classname is the current class name with leading underscore(s) stripped. Truncation may occur when the mangled name would be longer than 255 characters. When the class name consists of only underscores, no mangling occurs.

(Python) Sieve of Eratostenes - Kartoffel

Sun, 29 Jun 2008 12:58:00 GMT

An (probably inefficient) implementation of the Sieve of Eratostenes. The function returns a list containing all the prime numbers between 0 and the number passed to it.

(Python) Unit tests with Python - chombee

Mon, 16 Jun 2008 10:35:25 GMT

Test-first programming, in which you write the unit tests first with the unittest module and then work on the code until it passes all the tests, seems like a good substitute for writing interfaces or documentation first. The unit tests are like an API, describing the interface of the code being tested. And they lend themselves well to refactoring. This is a first attempt at a unit test for the messager.py module posted earlier.

(Python) Messager pattern from Panda3D - chombee

Wed, 11 Jun 2008 07:03:17 GMT

This is my implementation of the messager pattern used by Panda3D for event handling. It's a really nice idea but I think Panda's version is implemented weirdly, it uses the subscribe objects as keys in the dictionary. That means that if you want more than one object to subscribe to the same message you _have_ to subclass DirectObject and use self.accept(...), can't just call the messager directly or you'll get a different behaviour, it means that a single object instance can't subscribe two different functions to the same message, and it means that your _objects_ have to be _hashable_ (!) because the messager uses them as keys in a dictionary. It seems to me that it would be much simpler if the messager's dictionary just mapped message names to function objects, so that's what I did. Use this pattern when you have a lot of objects spread throughout the class hierarchy that need to communicate with each other. It's a way of implementing one-to-many or many-to-many communication, in which an object can send a message to many receivers without needing to know who those receivers are, or how many receivers there are, or even if there are any receivers (although an object can potentially check all these things if it wants to). The singleton messager object receives messages from broadcaster objects and forwards them to receiver objects. Setup a single, simple, generic, system- wide messaging system, instead of creating different systems for each different type of message or messaging relation. The disadvantage of just implementing this pattern once and using it everywhere is that with lots of senders and receivers it might become difficult to understand and debug message-based behaviour. Particularly if the order in which messages are sent and received becomes important, when you send a message with this pattern there's no way of knowing in what order the receiver objects will receive the message, and therefore know way of knowing in what order their responses will be executed, and those responses may include sending more messages. You can implement some ordering relations by having an object receive a message, deal with it, then send a different message to other recievers, but I wouldn't want to overuse that. Also you have to be careful to avoid clashes in message names. The GoF Mediator and Observer patterns are similar in that they enable a mode of communication between objects in which the sender object broadcasts a message without needing to know all of the receiver objects, and the receiver objects can receive messages without being tightly coupled to the sender object(s). In the GoF Mediator pattern, the Mediator object is more than just a messager that passes messages between other objects and leaves the behaviour up to the others. The mediator actually encapsulates the interaction behaviour between objects, deciding which methods to call on which objects each time it receives a notification from an object. Mediator centralises control of how objects cooperate in the mediator class, whereas the Messager pattern leaves this control distributed throughout the objects themselves. In the GoF observer pattern a one-to-many dependency is setup, there is no separate Messager object but rather the sender object itself maintains the list of reciever object and notifies them of new messages. With its separate messager object the Messager pattern enables many-to-many dependencies as well as one-to-many.

(Python) Reading and writing text files in Python - chombee

Mon, 09 Jun 2008 09:48:40 GMT

(Python) Creating list-like objects in Python - chombee

Sun, 08 Jun 2008 18:34:00 GMT

(Python) Creating dictionary-like objects in Python using DictMixin - chombee

Mon, 02 Jun 2008 11:45:35 GMT

(Python) Adding and removing collide masks - chombee

Fri, 30 May 2008 12:20:55 GMT

(Python) Panda3D's BitMask32 class (collision masks) - chombee

Fri, 30 May 2008 11:35:29 GMT

(Python) Hello World - erl

Thu, 29 May 2008 12:05:33 GMT

(Python) Código a tocar para usar twisted desde un servicio de red en windows - buscarini

Tue, 27 May 2008 05:38:20 GMT

Al intentar importar reactor windows da un error de acceso denegado.

(Python) get memory usage of current process on unix - fnl

Mon, 26 May 2008 23:03:02 GMT

(Python) YouTube Batch Download Script - abhiomkar

Sun, 25 May 2008 14:02:29 GMT

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(Python) iterates over the bytes of string - ishikawa

Thu, 15 May 2008 23:41:29 GMT

(Python) read a big5 file and print to stdout in utf8 - ckyang74

Thu, 15 May 2008 18:55:14 GMT

(Python) Recursively find subversion working copies and update - claytron

Thu, 15 May 2008 01:05:05 GMT

Little utility script I wrote to find subversion working copies and update them. If no arguments are given the script starts from the current directory.

(Python) Python Regular Expression Cheat Sheet - qrist0ph

Tue, 13 May 2008 07:57:58 GMT

(Python) Format Date - qrist0ph

Tue, 13 May 2008 06:21:11 GMT

(Python) Run Shell Command - qrist0ph

Tue, 13 May 2008 06:12:28 GMT

(Python) Python Filesystem Cheat Sheet - qrist0ph

Tue, 13 May 2008 06:11:29 GMT