Showing posts from June, 2005

Keyword-based logging with the py library

I've been experimenting lately with the logging functionality recently introduced in the py library. Most of the functionality is still in early experimental stage, but the main ideas are pretty well defined. I want to review some of these ideas here and hopefully get some feedback.

Holger Krekel, the main py library developer, introduced the idea of keyword-based logging and of logging producers and consumers. A log producer is an object used by the application code to send messages to various log consumers. The consumers can be STDOUT, STDERR, log files, syslog, the Windows Event Log, etc. When you create a log producer, you define a set of keywords that are then used to both route the logging messages to consumers, and to prefix those messages.

Here's a quick example of code that works with the current svn version of the py library (which you can get from I saved the following code in a file called

import py

log = p…

Handling the 'Path' Windows registry value correctly

A recent recipe posted to the Python Cookbook site shows how to manipulate environment variables in Windows by modifying the registry. I've been using something similar in my code, mainly for adding directories on the fly to the 'Path' environment variable by modifying the \HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Session Manager\Environment\Path registry value.

Here are two simple functions for getting and setting a registry value of type string (REG_SZ):def get_registry_value(reg, key, value_name):
k = _winreg.OpenKey(reg, key)
value = _winreg.QueryValueEx(k, value_name)[0]
return value

def set_registry_value(reg, key, value_name, value):
k = _winreg.OpenKey(reg, key, 0, _winreg.KEY_WRITE)
value_type = _winreg.REG_SZ
_winreg.SetValueEx(k, value_name, 0, value_type, value)
To add a directory dir to the Path registry value, you would do:reg = _winreg.ConnectRegistry(None, _winreg.HKEY_LOCAL_MACHINE)
key = r"SYSTEM\CurrentControlS…