Popular recipes by Oren Tirosh

ctypes CDLL with automatic errno checking (Python)

2017-01-03T10:31:26-08:00

Python recipe 580741 by Oren Tirosh .

This class extends ctypes.CDLL with automatic checking of errno and automatically raises an exception when set by the function.

Probably the fastest memoization decorator in the world (Python)

2012-08-02T07:27:12-07:00

Python recipe 578231 by Oren Tirosh (cache, decorator, memo, memoization).

With apologies to a certain European brand of beer, this is probably the fastest memoization decorator in the world. Implemented using the __missing__ method in a dict subclass.

Mixin for pickling objects with slots (Python)

2013-01-21T08:55:57-08:00

Python recipe 578433 by Oren Tirosh (pickle, unpickle, __slots__).

This mixin makes it possible to pickle/unpickle objects with __slots__ defined.

One-liner to show the caller of the current function. (Python)

2013-02-12T13:13:16-08:00

Python recipe 578422 by Oren Tirosh (_getframe).

This is a quick one-liner to produce the filename and line number of the caller of the current function.

Code to source and back (Python)

2012-12-01T08:59:49-08:00

Python recipe 578353 by Oren Tirosh (ast, decompile, recompile, uncompile).

Converts a code object to a source code snippet and back: c == recompile(*uncompile(c))

This is useful, for example, if you want to apply an AST transformation to the code.

How to read millions of hexadecimal numbers into a numpy array quickly (Python)

2012-06-27T06:03:40-07:00

Python recipe 578177 by Oren Tirosh (numpy).

The numpy.fromfile() function supports binary formats or decimal text. How do you read millions of hexadecimal numbers quickly?

Monotonic local time. And sandwich. (Python)

2013-01-03T08:28:36-08:00

Python recipe 578270 by Oren Tirosh (daylight, dst, time).

A Mutton, Lettuce and Tomato sandwich is generally agreed to be the greatest thing in the world. But a different kind of MLT comes in at a close second: Monotonic Local Time. This is a time value in your local timezone that takes care of that annoying hour that happens once a year where time goes backwards. It works by extending the previous day by a couple of hours (24, 25 etc) until after the switch.

Retry loop (Python)

2013-05-24T05:19:50-07:00

Python recipe 578163 by Oren Tirosh (exception, generator, loop, retry, timeout). Revision 4.

Encapsulates the logic of a retry loop using a generator function.

Immutable class decorator (Python)

2012-08-05T08:30:41-07:00

Python recipe 578233 by Oren Tirosh (decorator, immutable).

Apply this decorator to a class with __slots__. Members will be mutable during the execution of __init__ but read-only afterwards.

Context manager to atomically replace a file (Python)

2012-06-17T12:09:49-07:00

Python recipe 578166 by Oren Tirosh (atomic, contextmanager, file, replace). Revision 3.

This context manager ensures that a file's content is either replaced atomically with new contents or left unchanged. An exception or other error will not leave it empty or with partial content.

Context manager to prevent calling code from catching exceptions (Python)

2012-06-17T09:20:56-07:00

Python recipe 577863 by Oren Tirosh (context_manager, exception).

The following context manager causes any exceptions raised inside it to print a stack trace and exit immediately. The calling scope is not given a chance to catch the exception.

Teach the hashbang header new tricks using a dual mode shell/python script (Python)

2011-08-21T07:27:05-07:00

Python recipe 577851 by Oren Tirosh (hashbang, interpreter, options, python, sh, shell).

This dual-mode script is both a Posix shell script and a python script. The shell part looks like a triple-quoted string to the Python interpreter. The shell does not reach anything after the exec statement.

Pickle the interactive interpreter state (Python)

2008-05-20T10:36:50-07:00

Python recipe 572213 by Oren Tirosh (sysadmin). Revision 2.

This code extends the pickle module to enable pickling of functions and classes defined interactively at the command prompt. You can save the interpreter state by pickling the __main__ module and restore it later.

Unicode repr (Python)

2007-12-22T04:41:40-08:00

Python recipe 541082 by Oren Tirosh .

Alternative to the builtin repr() uses the \N{FULL NAME} format instead of \uXXXX for unicode strings.

Frozen dictionaries (Python)

2005-05-16T06:20:36-07:00

Python recipe 414283 by Oren Tirosh (algorithms).

A frozendict is a dictionary that cannot be modified after being created - but it is hashable and may serve as a member of a set or a key in a dictionary.

Finding the last item in a loop (Python)

2005-03-17T08:37:03-08:00

Python recipe 392015 by Oren Tirosh (algorithms).

An method to detect the last item in a loop.