libaaron 1.1.11

trivial functions I like to pack along for various things

Just my library of handy functions I like to bring along.

Contents

• reify

• cached

• w

• flatten

• quiteinterrupt

• DotDict

• PBytes

  • Enum

reify

reify is a decorator I stole from the Pylons project that I like to use frequently.

from the docstring:

Use as a class method decorator. It operates almost exactly like the Python @property decorator, but it puts the result of the method it decorates into the instance dict after the first call, effectively replacing the function it decorates with an instance variable. It is, in Python parlance, a non-data descriptor.

cached

cached is a decorator that makes a property but caches its results. It’s functionally similar to reify, but it dynamically creates a “private” attribute to cache the result instead of messing with descriptors. This approach is comppatible with slots. I love slots.

w

w is a function that takes an iterable with a context manager (like a file object) and yields from that iterable inside its context manager.

>>> # instead of this:
>>> with open('myfile.txt') as mf:
...     for line in mf:
...         # do something
...
>>> # you can do this:
>>> for line in w(open('myfile.txt')):
...     # do something
...

flatten

flatten is a function that takes an iterable as an arguments and recursively yields all contents from nested iterables (except strings, which are yielded as strings). The optional second argument is a function that will be used to convert any mappings into iterables before yielding from them (in the event you want to yield from their values or something else).

quiteinterrupt

quiteinterrupt is a function that adds a signal handler which silences the stacktrace when the a script is stopped with a keyboard interrupt. It can optionally print a message on interrupt.

DotDict

DotDict is a subclass of dict which allows fetching items with dot syntax. Useful as an object_hook when deserializing JSON, perhaps.

PBytes

PBytes is a subclass of int which has a __str__ that shows interprets it as a number of bytes and make a human readable format. It can also parse a number of bytes from a string.

>>> print(PBytes(2134963))
2.0 MiB
>>> PBytes.from_str('35.8 KB')
PBytes(36659)
>>> PBytes.from_str('35.8 KB', decimal=True)
PBytes(35800)

Internally, it’s just an integer, so you can do any integer operations with it. Note that from_str does not attempt to determine whether it is a binary or decimal format. Default is binary. Use decimal=True to explicitely change the behavior.

It also has a human_readable method which returns a number and the units for easily constructing alterative representations:

>>> PBytes(83629).human_readable()
(81.6689453125, 'K')
>>> '%d%s' % PBytes(83629).human_readable()
'81K'
>>> '%d%s' % PBytes(83629).human_readable(decimal=True)
'83K'

Enum

Make enum.Enum objects, but with nicer syntax.

>>> class var(libaaron.Enum):
...     foo
...     bar
...     baz
...
>>> var.foo
<var.foo: 1>
>>> var.bar
<var.bar: 2>
>>> var.baz
<var.baz: 3>
>>> type(var)
<class 'enum.EnumMeta'>

Note that the resulting object is the same type as those created with enum.Enum, not a work-alike object.