Python 3.4

Used for a lightning talk at Pražské Pyvo and a full talk at Brněnské Pyvo, both March 2014

Transcript

1. Python 3.4
   (party!)
   Petr Viktorin
   encukou@gmail.com
   Brněnské Pyvo, 2014-03-27
   

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2. Python 3.3
   u'string'
   

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3. Python 3.3
   u'string'
   yield from
   

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4. Python 3.3
   u'string'
   yield from
   venv
   

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5. Python 3.3
   u'string'
   yield from
   venv
   __qualname__
   

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6. Python 3.3
   u'string'
   yield from
   venv
   __qualname__
   unittest.mock
   

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7. Python 3.3
   u'string'
   yield from
   venv
   __qualname__
   unittest.mock
   Function signature objects
   

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8. Python 3.4
   2014-03-16
   

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9. yield from →
   asyncio
   

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10. yield from →
    asyncio
    "WSGI for event loops"
    

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11. yield from →
    asyncio
    "WSGI for event loops"
    twisted, tornado, gevent
    

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12. yield from →
    asyncio
    "WSGI for event loops"
    twisted, tornado, gevent
    event loop, tasks, calbacks,
    futures/deferreds
    networking IO
    

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13. venv →
    venv + ensurepip
    

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14. Commonly reinvented wheels
    

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15. Commonly reinvented wheels
    belong in the standard library
    

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16. enum
    >>> from enum import Enum
    >>> class Color(Enum):
    ... red = 1
    ... green = 2
    ... blue = 3
    >>> for c in Color:
    ... print(c)
    Color.red
    Color.green
    Color.blue
    

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17. pathlib
    >>> from pathlib import Path
    >>> p = Path('.')
    >>> p.isdir()
    True
    >>> p / 'slides.tex'
    PosixPath('./slides.tex')
    >>> (p / 'slides.tex').open().readline()
    '\\documentclass[20pt]{beamer}\n'
    

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18. statistics
    >>> data = [1e30, 1, 3, -1e30]
    >>> sum(data) / len(data)
    0.0
    >>> from statistics import mean
    >>> mean(data)
    1.0
    

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19. __qualname__ →
    Pickle format 4
    

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20. inspect CLI
    $ python -m inspect re:search
    def search(pattern, string, flags=0):
    """Scan through string looking for a match
    to the pattern, returning a match object,
    or None if no match was found."""
    return _compile(pattern, flags).search(string)
    

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21. re.fullmatch
    re.search('^abc$', string)
    re.match('abc$', string)
    re.fullmatch('abc', string)
    

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22. textwrap.shorten
    >>> textwrap.shorten('Hello world! You are beautiful!', 20)
    'Hello world! [...]'
    

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23. with
    

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24. with
    with what?
    

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25. with
    with what?
    with contextlib.suppress:
    with contextlib.redirect_stdout:
    

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26. with
    with what?
    with contextlib.suppress:
    with contextlib.redirect_stdout:
    with unittest.TestCase.subTest():
    with unittest.TestCase.assertLogs():
    

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27. with
    with what?
    with contextlib.suppress:
    with contextlib.redirect_stdout:
    with unittest.TestCase.subTest():
    with unittest.TestCase.assertLogs():
    with aifc.open(...):
    with sunau.open(...):
    with select.epoll(...):
    with dbm.open(...):
    with wave.open(...):
    

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28. signature →
    inspect, pydoc & help()
    improvements
    

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29. signature →
    inspect, pydoc & help()
    improvements
    unittest.mock →
    Mock objects now check
    signatures
    

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30. functools.partialmethod
    

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31. functools.partialmethod
    import functools
    class A:
    def greet(self, greeting, subject):
    print('{}, {}!'.format(greeting, subject))
    say_hello = functools.partialmethod(greet, 'Hello')
    A().say_hello('world') # --> Hello, world!
    

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32. functools.singledispatch
    

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33. functools.singledispatch
    from functools import singledispatch
    from collections.abc import Iterable
    @singledispatch
    def upper(arg):
    raise NotImplementedError()
    @upper.register(str)
    def _(arg):
    return arg.upper()
    @upper.register(Iterable)
    def _(arg):
    return [upper(a) for a in arg]
    print(upper('abc')) # --> ABC
    print(upper(['a', 'b', 'c'])) # --> ['A', 'B', 'C']
    

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34. weakref.WeakMethod
    

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35. importlib simplification
    

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36. CPython improvements
    

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37. CPython improvements
    __del__ + ref loops?
    no problemo
    

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38. CPython improvements
    __del__ + ref loops?
    no problemo
    30% faster startup
    

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39. docs.python.org/3.4/whatsnew
    asyncio
    ensurepip
    enum
    pathlib
    statistics
    pickle 4
    inspect CLI
    re.fullmatch
    textwrap.shorten
    with
    signature support
    functools.partialmethod
    functools.singledispatch
    weakref.WeakMethod
    CPython improvements
    ... and more!
    

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