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https://github.com/sametmax/Bat-belt

A collection of gagdets make Python even more powerful
https://github.com/sametmax/Bat-belt

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A collection of gagdets make Python even more powerful

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README 

        
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A collection of gagdets that makes Python even more powerful

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There is not real structure for this lib, it's just a bunch of snippets I put together because I use them often.



Not all of them are documented here, few of them have tests, it's zlib licence, you know the drill...



To timestamp

=============



datetime.fromtimestamp exists but not the other away around, and it's not likely to change anytime soon (see: http://bugs.python.org/issue2736). In the meantime::



    >>> from datetime import datetime

    >>> to_timestamp(datetime(2000, 1, 1, 2, 1, 1))

    946692061

    >>> datetime.fromtimestamp(946688461) # tu as codé celle là et pas l'autre connard !

    datetime.datetime(2000, 1, 1, 2, 1, 1)



Get this nest value or a default

=================================



Don't::



    try:

        res = data['key'][0]['other key'][1]

    except (KeyError, IndexError):

        res = "value"



Do::



    get(data, 'key', 0, 'other key, 1, default="value")



For attributes::



    devise = attr(car, 'insurance', 'expiration_date', 'timezone')



Iteration tools missing in itertools

===================================================================================



Iteration by chunk or with a sliding window::



    >>> for chunk in chunks(l, 3):

    ...     print list(chunk)

    ...

    [0, 1, 2]

    [3, 4, 5]

    [6, 7, 8]

    [9]

    >>> for slide in window(l, 3):

    ...     print list(slide)

    ...

    [0, 1, 2]

    [1, 2, 3]

    [2, 3, 4]

    [3, 4, 5]

    [4, 5, 6]

    [5, 6, 7]

    [6, 7, 8]

    [7, 8, 9]



Get the first element an any iterable (not just indexable) or the first one to be True::



    >>> first(xrange(10))

    0

    >>> first_true(xrange(10))

    1

    >>> first([], default="What the one thing we say to the God of Death ?")

    'What the one thing we say to the God of Death ?'



Sorted Set

===================================================================================



Slow but useful data structure::



    >>> for x in sset((3, 2, 2, 2, 1, 2)):

    ...     print x

    ...

    3

    2

    1



Dictionaries one liners

===================================================================================



I wish + was overloaded for dicts::



    >>> dmerge({"a": 1, "b": 2}, {"b": 2, "c": 3})

    {'a': 1, 'c': 3, 'b': 2}



Sometimes you do not want to simply overwrite the values inside the original dict, but merge them in custom fashion::



    >>> def my_merge(v1, v2):

    ...     if isinstance(v1, dict) and isinstance(v2, dict):

    ...         return dmerge(v1, v2)

    ...     return v2

    >>> dmerge({"a": 1, "b": {'ok': 5}}, {"b": {'ko': 5 }, "c": 3}, my_merge)

    {'a': 1, 'c': 3, 'b': {'ko': 5, 'ok': 5}}



Original dicts are not modified, but this will modify them::



    >>> from batbelt.structs import rename

    >>> rename({"a": 1, "b": 2})

    >>> rename({"a": 1, "b": 2}, 'b', 'z')

    {u'a': 1, u'z': 2}



(not thread safe).



Twited but satisfying::



    >>> from batbelt.structs import unpack

    >>> dct = {'a': 2, 'b': 4, 'z': 42}

    >>> a, b, c = unpack(dct, 'a', 'b', 'c', default=1)

    >>> a

    2

    >>> b

    4

    >>> c

    1



String tools

===================================================================================



The mandatory "slufigy"::



    >>> slugify(u"Hélo Whorde")

    helo-whorde



You get better slugification if you install the `unidecode` lib, but it's optional. You can specify `separator` if you don't like `-` or call directly `normalize()` (the underlying function) if you wish more control.



The module also feature html_escape/unescape that is not useless and json_dumps/loads that understand datetime by default. Look at the source for these, I'm lazy (PL for documentation are welcome).



There is also a poor man template system using the `format()` string method on a file content. No loop, but still nice for quick and dirty file generation :



    from batbelt.strings import render



    render('stuff.conf.tpl', {"var": "value"}, "/etc/stuff.conf")



Import this

===================================================================================



`__import__` is weird. Let's abstract that ::



    TaClasse = import_from_path('foo.bar.TaClasse')

    ton_obj = TaClasse()



Catpure prints

===================================================================================



A context manager to deal with this libs that print the result instead of returning it :



    >>> with capture_ouput() as (stdout, stderr):

    ...    print "hello",

    ...

    >>> print stdout.read()

    hello

    >>> stdout.close()



Create a decorator that accept arguments

===================================================================================



I never remember how to do this. And I don't have to anymore.



First, write the decorator::



    # all arguments after 'func' are your decorator argument

    @decorator_with_args()

    def your_decorator(func, arg1, arg2=None):



        if arg1:

            # do stuff here



        # do your usual decorator jimbo jumbo, wrapping, calling, returning...

        def wrapper():

            return func(arg2)



        return wrapper



Enjoy :



    @your_decorator(False, 1)

    def hop(un_arg):

        # do stuff in the decorated function



Add a any directory to the PYTHON PATH

===========================================



Accepts shell variables and relative paths :



    from batbelt.utils import add_to_pythonpath

    add_to_pythonpath("~/..")



You can (and probably wants) specify a starting point if you pass a relative path. The default starting point is the result is `os.getcwd()` while you probably wants the directory containing you script. To to so, pass `__file__`:



    add_to_pythonpath("../..", starting_point=__file__)



`starting_point` can be a file path (basename will be stripped) or a directory name. If will be from there that the reltive path will be calculated.



You can also choose where in the `sys.path` list the your path will be added by passing `insertion_index`, which default to the after the last existing item.



Poor man task queue

===================================================================================================



You don't always need the guaranty of a big lib, you just need a little worker to do the job outside of the main thread::



    from batbelt.parallel import worker



    @worker()

    def task(arg):

        arg = arg + 10

        return arg



    # start the worker

    process = task.start()



    # send tasks

    for x in range(10):

        process.put(x)



    # (optionaly) get results

    for x in range(10):

        print process.get()



    ## 10

    ## 11

    ## 12

    ## 13

    ## 14

    ## 15

    ## 16

    ## 17

    ## 18

    ## 19



    # stop the worker

    process.stop()



The worker use multiprocessing by default, but if you prefer threads: `@worker(method="tread")`.



If you look for it in the source code, you'll see goodies such as Singletong, Null Pattern implementation and other things you don't use that often.