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I hope this article encourages you to think about your command line programs in a different light, and to treat them as first class objects. Using inheritance to share code is so common in other areas of development that it is hardly given a second thought in most cases. As has been shown with the SQLiteAppBase programs, the same technique can be just as powerful when applied to building command line programs, saving development time and testing effort as a result. CommandLineApp has been used as the foundation for dozens of types of programs, and could be just what you need the next time you have to write a new command line program.

One of the main difficulties I've had using parser generators has been the difficulty of figuring out why a grammar didn't work. Fixing shift-reduce and reduce-reduce conflicts seemed like voodoo to me, and though I slightly understand better how to fix such things now it's still a different mode of thinking that I don't want to try to get into when I just want to parse something simple. PyMeta uses a variation on the Parsing Expression Grammar (PEG) approach to parsing. The chief consequence of this is there's no possibility of ambiguity in a parse: a successful parse will yield exactly one result, and you can trace the control flow through the grammar to figure out how it got there.

Last week we looked at the itertools module and how its iterator based functions can be faster than doing things from scratch. One of the examples showed a function using itertools.takewhile to be much faster than one using itertools.groupby. Some feedback we got, asked, what then is the point of groupby if it's just a slower version of other functionality?

Pycha is a very simple Python package for drawing charts using the great Cairo library. Its goals are: Lightweight Simple to use Nice looking with default values Customization It won't try to draw any possible chart on earth but draw the most common ones nicely. There are some other options you may want to look at like pyCairoChart Pycha is based on Plotr which is based on PlotKit. Both libraries are written in JavaScript and are great for client web programming. I needed the same for the server side so that's the reason I ported Plotr to Python. Now we can deliver charts to people with JavaScript disabled or embed them in PDF reports.

Tired of debugging Python using print statements? Don't like the cumbersome PDB (Python debugger) console? Prefer using Vim for coding your Python programs? VimPdb is the solution - allows debugging Python in an IDE-fashion, right within the Vim editor.

interpreter:>>>import matplotlib>>>matplotlib.interactive(True)>>>matplotlib.use("WXAgg")>>>from matplotlib.pylab import *>>>plot([1,2,3])>>>xlabel('time (s)') 

> Is there a way to find the number of processors on a machine (on linux/ > windows/macos/cygwin) using python code (using the same code/cross > platform code)? From processing <http://cheeseshop.python.org/pypi/processing/0.34> : def cpuCount():     '''     Returns the number of CPUs in the system     '''     if sys.platform == 'win32':         try:             num = int(os.environ['NUMBER_OF_PROCESSORS'])         except (ValueError, KeyError):             pass     elif sys.platform == 'darwin':         try:             num = int(os.popen('sysctl -n hw.ncpu').read())         except ValueError:             pass     else:         try:             num = os.sysconf('SC_NPROCESSORS_ONLN')         except (ValueError, OSError, AttributeError):             pass     if num >= 1:         return num     else:         raise NotImplementedError --

Osh (Object SHell) is a tool that integrates the processing of structured data, database access, and remote access to a cluster of nodes. These capabilities are made available through a command-line interface (CLI) and a Python application programming interface (API). Osh processes streams of Python objects using simple commands. Complex data processing is achieved by command sequences in which the output from one command is passed to the input of the next. This is similar to composing Unix commands using pipes. However, Unix commands pass strings from one command to the next, and the commands (grep, awk, sed, etc.) are heavily string-oriented. Osh commands send primitive Python types such as strings and numbers; composite types such as tuples, lists and maps; objects representing files, dates and times; or even user-defined objects.

The pyparsing module is an alternative approach to creating and executing simple grammars, vs. the traditional lex/yacc approach, or the use of regular expressions. The pyparsing module provides a library of classes that client code uses to construct the grammar directly in Python code.

PyCHM - Python bindings for CHMLIB PyCHM is a package that provides bindings for Jed Wing's CHMLIB library. The chm package contains four modules, namely chm.chm, chm.chmlib, chm.extra and chm._chmlib. chm.chmlib is a low level wrapper module around the API provided by the C library chmlib. Quoted from Jed's README: chmlib is a small library designed for accessing MS ITSS files. The ITSS file format is used for Microsoft Html Help files (.chm), which have been the predominant medium for software documentation from Microsoft during the past several years, having superceded the previously used .hlp file format. chm.chm provides some high level functionality over chm.chmlib, such as access to the .chm file contents tree. chm.extra contains extra functionality to allow detection encodings in the CHM archives and to support full-text search.

Pyro is short for PYthon Remote Objects. It is an advanced and powerful Distributed Object Technology system written entirely in Python, that is designed to be very easy to use. Never worry about writing network communication code again, when using Pyro you just write your Python objects like you would normally. With only a few lines of extra code, Pyro takes care of the network communication between your objects once you split them over different machines on the network. All the gory socket programming details are taken care of, you just call a method on a remote object as if it were a local object!