Top-rated recipes by Giampaolo Rodolà

Python interpreter auto-completion and history (Python)

2014-01-09T10:04:47-08:00

Python recipe 578098 by Giampaolo Rodolà (bashrc, completion, history, python, pythonstartup). Revision 5.

Useful in case you don't want to install iPython.

Log watcher (tail -F *.log) (Python)

2014-04-04T15:54:03-07:00

Python recipe 577968 by Giampaolo Rodolà (color, log, logging, monitor, python, rotate, rotations, tail). Revision 10.

A python class which "watches" a directory and calls a callback(filename, lines) function every time one of the files being watched gets written, in real time.

Practically speaking, this can be compared to "tail -F *.log" UNIX command, but instead of having lines printed to stdout a python function gets called.

Similarly to tail, it takes care of "watching" new files which are created after initialization and "unwatching" those ones which are removed in the meantime. This means you'll be able to "follow" and support also rotating log files.

History

rev5 (2013-04-05):
- sizehint parameter
rev4 (2013-03-16):
- python 3 support (also dropped support for python <= 2.5)
- windows support
- unit tests
- main class can also be used as a context manager
rev3 (2012-01-13): initial release

Disk usage (Python)

2012-10-06T15:33:40-07:00

Python recipe 577972 by Giampaolo Rodolà (disk, python, python3, space, statistics, usage). Revision 6.

Provides disk usage statistics (total, used and free disk space) about a given path.

This recipe was initially developed for psutil:

http://code.google.com/p/psutil/issues/detail?id=172

...and then included into shutil module starting from Python 3.3:

The recipe you see here is a modified version of the latter one in that the Windows implementation uses ctypes instead of a C extension module. As such it can be used with python >= 2.5.

Deprecated decorator (Python)

2013-12-14T01:24:31-08:00

Python recipe 577819 by Giampaolo Rodolà (decorator, deprecated, python). Revision 3.

A decorator to deprecate a function and provide a new one as replacement.

Handle exit context manager (Python)

2014-08-01T08:28:07-07:00

Python recipe 577997 by Giampaolo Rodolà (atexit, contextlib, contextmanager, exit, python, python3, shutdown, sigint, signal, sigterm). Revision 23.

A context manager which properly handles SIGTERM (SystemExit) and SIGINT (KeyboardInterrupt) signals, registering a function which is always guaranteed to be called on interpreter exit. Also, it makes sure to execute previously registered functions as well (if any).

asyncore scheduler (Python)

2011-07-25T23:42:21-07:00

Python recipe 577808 by Giampaolo Rodolà (asynchronous, asyncore, heapq, nonblocking, scheduler, twisted). Revision 5.

The thing I miss mostly in asyncore is a system for calling a function after a certain amount of time without blocking. This is crucial for simple tasks such as disconnecting a peer after a certain time of inactivity or more advanced use cases such as bandwidth throttling.

This recipe was initially inspired by Twisted's internet.base.DelayedCall class:

http://twistedmatrix.com/trac/browser/tags/last_vfs_and_web2/twisted/internet/base.py#L34

...then included into pyftpdlib:

http://code.google.com/p/pyftpdlib/issues/detail?id=72

...and finally proposed for inclusion into asyncore:

http://bugs.python.org/issue1641

Register exit function (Python)

2016-05-31T00:42:47-07:00

Python recipe 580672 by Giampaolo Rodolà (exit, python, signal). Revision 3.

This is a function / decorator which registers a function which will be executed on "normal" interpreter exit or in case one of the signals is received by this process (differently from atexit.register()). Also, it makes sure to execute any other function which was previously registered via signal.signal(). If any, it will be executed after our own fun. The full blogpost explaining why you should use this instead of atexit module is here: http://grodola.blogspot.com/2016/02/how-to-always-execute-exit-functions-in-py.html

socket.sendfile() (Python)

2014-06-13T13:41:25-07:00

Python recipe 578889 by Giampaolo Rodolà (backport, performance, python, sendfile). Revision 2.

This is a backport of socket.sendfile() for Python 2.6 and 2.7. socket.sendfile() will be included in Python 3.5: http://bugs.python.org/issue17552

Server supporting IPv4 and IPv6 (Python)

2017-03-05T11:00:27-08:00

Python recipe 578504 by Giampaolo Rodolà (dualstack, ipv4, ipv6, ipv6_v6only, networking, python, socket). Revision 13.

Utility functions to create a single server socket which able to listen on both IPv4 and IPv6. Inspired by: http://bugs.python.org/issue17561

Expected usage:

>>> sock = create_server_sock(("", 8000))
>>> if not has_dual_stack(sock):
...     sock.close()
...     sock = MultipleSocketsListener([("0.0.0.0", 8000), ("::", 8000)])
>>>

From here on you have a socket which listens on port 8000, all interfaces, serving both IPv4 and IPv6. You can start accepting new connections as usual:

>>> while True:
...     conn, addr = sock.accept()
...     # handle new connection

Supports UNIX, Windows, non-blocking sockets and socket timeouts. Works with Python >= 2.6 and 3.X.

@unittest.skip_others decorator (Python)

2012-08-06T02:20:19-07:00

Python recipe 578234 by Giampaolo Rodolà (python, python3, skip, unittest). Revision 3.

Decorator which skips all tests except the one decorated with it. Based on original proposal on python-ideas: http://mail.python.org/pipermail/python-ideas/2010-August/007992.html

Wait for PID and check for PID existance (POSIX) (Python)

2012-04-15T14:13:02-07:00

Python recipe 578022 by Giampaolo Rodolà (exists, exit, pid, process, status, timeout, wait). Revision 7.

Two functions: one which waits for a certain PID to terminate (with optional timeout), another one which checks whether a process with a given PID is running.

This was extracted from psutil project which also provides a Windows implementation.

Timeout functionality is implemented as a busy loop and it was inspired by http://bugs.python.org/issue5673.

Bytes-to-human / human-to-bytes converter (Python)

2012-02-02T16:09:52-08:00

Python recipe 578019 by Giampaolo Rodolà (bytes, conversion, converter, human, humanize, string). Revision 15.

Here goes.

Named constant type (Python)

2012-06-13T13:43:47-07:00

Python recipe 577984 by Giampaolo Rodolà (constant, named, python). Revision 7.

A simple constant type which overrides the base integer type to provide a useful name on str().

Coloured / highlighted version of string (Python)

2014-06-03T17:54:33-07:00

Python recipe 577818 by Giampaolo Rodolà (color, debugging, highlighting, shell). Revision 3.

Ok, this is really simple but I think it worths a recipe as it's one of those things I always use in shell scripts and for debugging in general.

Profile decorator (Python)

2011-08-02T19:08:58-07:00

Python recipe 577817 by Giampaolo Rodolà (profile, profiling, python).

A decorator for profiling a function which prints profiling results to stdout. This was originally proposed as a patch for inclusion into python stdlib:

http://bugs.python.org/issue9285

Note that on certain Linux systems pstats module isn't available, despite it is supposed to be part of Python stdlib. On my Ubuntu box I had to run "sudo apt-get install python-profile" first.