Codespit

In Python, assignment is a statement, not an expression, and can therefore not be used inside an arbitrary expression. This means that common C idioms like: or cannot be used as is in Python. The first example is better written using an iterator: for line in file: … do something with line … but the … Read more

I’ve been playing with asyncore and 2.2’s new generator model. Here’s the idea: Instead of passing events to callbacks, pass information to a single handle function (a generator) via instance attributes. When the handler needs more data from the network, use yield to pass control back to the asyncore dispatcher. Does it work? You bet. from YieldAsyncore import * class httpClient(YieldDispatcherWithSend): … Read more

(Optional). This module contains a faster reimplementation of the pickle module. Example: Using the cPickle module # File: cpickle-example-1.py try: import cPickle as pickle except ImportError: import pickle # fall back on Python version class Sample: def __init__(self, value): self.value = value sample = Sample(1) data = pickle.dumps(sample) print pickle print repr(data) <module ‘cPickle’ (built-in)> “(i__main__\012Sample\012p1\012(dp2\012S’value’\012p3\012I1\012sb.”

This module is used to serialize data; that is, convert data to and from character strings, so that they can be stored on file or sent over a network. It’s a quite a bit slower than marshal, but it can handle class instances, shared elements, and recursive data structures, among other things. There’s also a faster … Read more

This module provides a registry that you can use to register your own extension types. The pickle and copy modules use this registry to figure out how to process non-standard types. For example, the standard pickle implementation cannot deal with Python code objects, as shown by the following example: # File: copy-reg-example-1.py import pickle CODE = “”” print ‘good evening’ “”” … Read more

The “bdb” module provides the bdb.Bdb class, which you can subclass to create your own debugger. You can then override its methods to define custom behavior for breakpoints, tracing, and handling exceptions. Here’s a simple example of using the “bdb” module to create a basic debugger: pythonCopy codeimport bdb class MyDebugger(bdb.Bdb): def user_line(self, frame): self.set_trace(frame) … Read more

This module converts between Python data types and Sun’s external data representation (XDR). Example: Using the xdrlib module import xdrlib # # create a packer and add some data to it p = xdrlib.Packer() p.pack_uint(1) p.pack_string(“spam”) data = p.get_buffer() print “packed:”, repr(data) # # create an unpacker and use it to decode the data u … Read more

   We’re back after a server migration that caused codespit.com to fall over a bit harder than expected. Expect some glitches. The aggdraw Module An AGG-based drawing interface. The aggdraw module implements the basic WCK 2D Drawing Interface on top of the AGG library. This library supports anti-aliasing and alpha compositing, but is otherwise fully compatible with the WCK … Read more

This module provides a “functional” interface to the standard operators in Python. The functions in this module can be used instead of some lambda constructs, when processing data with functions like map and filter. They are also quite popular among people who like to write obscure code, for obvious reasons. Example: Using the operator module # File: operator-example-1.py import operator sequence = … Read more

In Python, variables that are only referenced inside a function are implicitly global. If a variable is assigned a new value anywhere within the function’s body, it’s assumed to be a local. If a variable is ever assigned a new value inside the function, the variable is implicitly local, and you need to explicitly declare … Read more