.. _python_36:
Python 3.6
==========
Python 3.6 beta 1 was released on 12 Sep 2016, and a summary of the new features can be found here:
.. table::
:widths: 30 50 20
+-----------------------------------------------------------------------------------------------------------+-----------------+
| **New Syntax Features** | **Status** |
+--------------------------------------------------------+--------------------------------------------------+-----------------+
| `PEP 498 <https://www.python.org/dev/peps/pep-0498/>`_ | Literal String Formatting | Complete |
+--------------------------------------------------------+--------------------------------------------------+-----------------+
| `PEP 515 <https://www.python.org/dev/peps/pep-0515/>`_ | Underscores in Numeric Literals | Complete |
+--------------------------------------------------------+--------------------------------------------------+-----------------+
| `PEP 525 <https://www.python.org/dev/peps/pep-0525/>`_ | Asynchronous Generators | |
+--------------------------------------------------------+--------------------------------------------------+-----------------+
| `PEP 526 <https://www.python.org/dev/peps/pep-0526/>`_ | Syntax for Variable Annotations (provisional) | Complete |
+--------------------------------------------------------+--------------------------------------------------+-----------------+
| `PEP 530 <https://www.python.org/dev/peps/pep-0530/>`_ | Asynchronous Comprehensions | |
+--------------------------------------------------------+--------------------------------------------------+-----------------+
| **New Built-in Features** |
+--------------------------------------------------------+--------------------------------------------------+-----------------+
| `PEP 468 <https://www.python.org/dev/peps/pep-0468/>`_ | Preserving the order of *kwargs* in a function | |
+--------------------------------------------------------+--------------------------------------------------+-----------------+
| `PEP 487 <https://www.python.org/dev/peps/pep-0487/>`_ | Simpler customization of class creation | |
+--------------------------------------------------------+--------------------------------------------------+-----------------+
| `PEP 520 <https://www.python.org/dev/peps/pep-0520/>`_ | Preserving Class Attribute Definition Order | |
+--------------------------------------------------------+--------------------------------------------------+-----------------+
| **Standard Library Changes** |
+--------------------------------------------------------+--------------------------------------------------+-----------------+
| `PEP 495 <https://www.python.org/dev/peps/pep-0495/>`_ | Local Time Disambiguation | |
+--------------------------------------------------------+--------------------------------------------------+-----------------+
| `PEP 506 <https://www.python.org/dev/peps/pep-0506/>`_ | Adding A Secrets Module To The Standard Library | |
+--------------------------------------------------------+--------------------------------------------------+-----------------+
| `PEP 519 <https://www.python.org/dev/peps/pep-0519/>`_ | Adding a file system path protocol | |
+--------------------------------------------------------+--------------------------------------------------+-----------------+
| **CPython Internals** |
+--------------------------------------------------------+--------------------------------------------------+-----------------+
| `PEP 509 <https://www.python.org/dev/peps/pep-0509/>`_ | Add a private version to dict | Won't do |
+--------------------------------------------------------+--------------------------------------------------+-----------------+
| `PEP 523 <https://www.python.org/dev/peps/pep-0523/>`_ | Adding a frame evaluation API to CPython | |
+--------------------------------------------------------+--------------------------------------------------+-----------------+
| **Linux/Window Changes** |
+--------------------------------------------------------+--------------------------------------------------+-----------------+
| `PEP 524 <https://www.python.org/dev/peps/pep-0524/>`_ | Make ``os.urandom()`` blocking on Linux | |
| | (during system startup) | |
+--------------------------------------------------------+--------------------------------------------------+-----------------+
| `PEP 528 <https://www.python.org/dev/peps/pep-0528/>`_ | Change Windows console encoding to UTF-8 | |
+--------------------------------------------------------+--------------------------------------------------+-----------------+
| `PEP 529 <https://www.python.org/dev/peps/pep-0529/>`_ | Change Windows filesystem encoding to UTF-8 | |
+--------------------------------------------------------+--------------------------------------------------+-----------------+
Other Language Changes:
.. table::
:widths: 90 10
+-------------------------------------------------------------------------------------------------------------+---------------+
| A *global* or *nonlocal* statement must now textually appear before the first use of the affected name in | |
| the same scope. Previously this was a SyntaxWarning. | |
+-------------------------------------------------------------------------------------------------------------+---------------+
| It is now possible to set a special method to None to indicate that the corresponding operation is not | |
| available. For example, if a class sets *__iter__()* to *None* , the class is not iterable. | |
+-------------------------------------------------------------------------------------------------------------+---------------+
| Long sequences of repeated traceback lines are now abbreviated as *[Previous line repeated {count} more | |
| times]* | |
+-------------------------------------------------------------------------------------------------------------+---------------+
| Import now raises the new exception *ModuleNotFoundError* when it cannot find a module. Code that currently | |
| checks for ImportError (in try-except) will still work. | |
+-------------------------------------------------------------------------------------------------------------+---------------+
| Class methods relying on zero-argument *super()* will now work correctly when called from metaclass methods | |
| during class creation. | |
+-------------------------------------------------------------------------------------------------------------+---------------+
Changes to built-in modules:
.. table::
:widths: 90 10
+--------------------------------------------------------------------------------------------------------------+----------------+
| `array <https://docs.python.org/3.6/whatsnew/3.6.html#array>`_ | |
+--------------------------------------------------------------------------------------------------------------+----------------+
| Exhausted iterators of *array.array* will now stay exhausted even if the iterated array is extended. | |
+--------------------------------------------------------------------------------------------------------------+----------------+
| `binascii <https://docs.python.org/3.6/whatsnew/3.6.html#binascii>`_ | |
+--------------------------------------------------------------------------------------------------------------+----------------+
| The b2a_base64() function now accepts an optional newline keyword argument to control whether the newline | Complete |
| character is appended to the return value | |
+--------------------------------------------------------------------------------------------------------------+----------------+
| `cmath <https://docs.python.org/3.6/whatsnew/3.6.html#cmath>`_ | |
+--------------------------------------------------------------------------------------------------------------+----------------+
| The new cmath.tau (Ï„) constant has been added | |
+--------------------------------------------------------------------------------------------------------------+----------------+
| New constants: *cmath.inf* and *cmath.nan* to match *math.inf* and *math.nan* , and also *cmath.infj* and | |
| *cmath.nanj* to match the format used by complex repr | |
+--------------------------------------------------------------------------------------------------------------+----------------+
| `collections <https://docs.python.org/3.6/whatsnew/3.6.html#collections>`_ |
+--------------------------------------------------------------------------------------------------------------+----------------+
| The new Collection abstract base class has been added to represent sized iterable container classes | |
+--------------------------------------------------------------------------------------------------------------+----------------+
| The new *Reversible* abstract base class represents iterable classes that also provide the *__reversed__()* | |
| method. | |
+--------------------------------------------------------------------------------------------------------------+----------------+
| The new *AsyncGenerator* abstract base class represents asynchronous generators. | |
+--------------------------------------------------------------------------------------------------------------+----------------+
| The *namedtuple()* function now accepts an optional keyword argument module, which, when specified, is used | |
| for the *__module__* attribute of the returned named tuple class. | |
+--------------------------------------------------------------------------------------------------------------+----------------+
| The verbose and rename arguments for *namedtuple()* are now keyword-only. | |
+--------------------------------------------------------------------------------------------------------------+----------------+
| Recursive *collections.deque* instances can now be pickled. | |
+--------------------------------------------------------------------------------------------------------------+----------------+
| `hashlib <https://docs.python.org/3.6/whatsnew/3.6.html#hashlib>`_ |
+--------------------------------------------------------------------------------------------------------------+----------------+
| BLAKE2 hash functions were added to the module. *blake2b()* and *blake2s()* are always available and support | |
| the full feature set of BLAKE2. | |
+--------------------------------------------------------------------------------------------------------------+----------------+
| The SHA-3 hash functions *sha3_224()*, *sha3_256()*, *sha3_384()*, *sha3_512()*, and *SHAKE* hash functions | |
| *shake_128()* and *shake_256()* were added. | |
+--------------------------------------------------------------------------------------------------------------+----------------+
| The password-based key derivation function *scrypt()* is now available with OpenSSL 1.1.0 and newer. | |
+--------------------------------------------------------------------------------------------------------------+----------------+
| `json <https://docs.python.org/3.6/whatsnew/3.6.html#json>`_ |
+--------------------------------------------------------------------------------------------------------------+----------------+
| *json.load()* and *json.loads()* now support binary input. Encoded JSON should be represented using either | |
| UTF-8, UTF-16, or UTF-32. | |
+--------------------------------------------------------------------------------------------------------------+----------------+
| `math <https://docs.python.org/3.6/whatsnew/3.6.html#math>`_ |
+--------------------------------------------------------------------------------------------------------------+----------------+
| The new math.tau (Ï„) constant has been added | Complete |
+--------------------------------------------------------------------------------------------------------------+----------------+
| `os <https://docs.python.org/3.6/whatsnew/3.6.html#os>`_ |
+--------------------------------------------------------------------------------------------------------------+----------------+
| A new *close()* method allows explicitly closing a *scandir()* iterator. The *scandir()* iterator now | |
| supports the context manager protocol. | |
+--------------------------------------------------------------------------------------------------------------+----------------+
| On Linux, *os.urandom()* now blocks until the system urandom entropy pool is initialized to increase the | |
| security. | |
+--------------------------------------------------------------------------------------------------------------+----------------+
| The Linux *getrandom()* syscall (get random bytes) is now exposed as the new *os.getrandom()* function. | |
+--------------------------------------------------------------------------------------------------------------+----------------+
| `re <https://docs.python.org/3.6/whatsnew/3.6.html#re>`_ |
+--------------------------------------------------------------------------------------------------------------+----------------+
| Added support of modifier spans in regular expressions. Examples: *'(?i:p)ython'* matches 'python' and | |
| 'Python', but not 'PYTHON'; *'(?i)g(?-i:v)r'* matches *'GvR'* and *'gvr'*, but not *'GVR'*. | |
+--------------------------------------------------------------------------------------------------------------+----------------+
| Match object groups can be accessed by *__getitem__*, which is equivalent to *group()*. So *mo['name']* is | |
| now equivalent to *mo.group('name')*. | |
+--------------------------------------------------------------------------------------------------------------+----------------+
| Match objects now support index-like objects as group indices. | |
+--------------------------------------------------------------------------------------------------------------+----------------+
| `socket <https://docs.python.org/3.6/whatsnew/3.6.html#socket>`_ |
+--------------------------------------------------------------------------------------------------------------+----------------+
| The *ioctl()* function now supports the *SIO_LOOPBACK_FAST_PATH* control code. | |
+--------------------------------------------------------------------------------------------------------------+----------------+
| The *getsockopt()* constants *SO_DOMAIN* , *SO_PROTOCOL*, *SO_PEERSEC* , and *SO_PASSSEC* are now supported. | |
+--------------------------------------------------------------------------------------------------------------+----------------+
| The *setsockopt()* now supports the *setsockopt(level, optname, None, optlen: int)* form. | |
+--------------------------------------------------------------------------------------------------------------+----------------+
| The socket module now supports the address family *AF_ALG* to interface with Linux Kernel crypto API. | |
| *ALG_*, *SOL_ALG* and *sendmsg_afalg()* were added. | |
+--------------------------------------------------------------------------------------------------------------+----------------+
| New Linux constants *TCP_USER_TIMEOUT* and *TCP_CONGESTION* were added. | |
+--------------------------------------------------------------------------------------------------------------+----------------+
| `ssl <https://docs.python.org/3.6/whatsnew/3.6.html#ssl>`_ |
+--------------------------------------------------------------------------------------------------------------+----------------+
| ssl supports OpenSSL 1.1.0. The minimum recommend version is 1.0.2. | |
+--------------------------------------------------------------------------------------------------------------+----------------+
| 3DES has been removed from the default cipher suites and ChaCha20 Poly1305 cipher suites have been added. | |
+--------------------------------------------------------------------------------------------------------------+----------------+
| *SSLContext* has better default configuration for options and ciphers. | |
+--------------------------------------------------------------------------------------------------------------+----------------+
| SSL session can be copied from one client-side connection to another with the new *SSLSession* class. TLS | |
| session resumption can speed up the initial handshake, reduce latency and improve performance. | |
+--------------------------------------------------------------------------------------------------------------+----------------+
| The new *get_ciphers()* method can be used to get a list of enabled ciphers in order of cipher priority. | |
+--------------------------------------------------------------------------------------------------------------+----------------+
| All constants and flags have been converted to *IntEnum* and *IntFlags*. | |
+--------------------------------------------------------------------------------------------------------------+----------------+
| Server and client-side specific TLS protocols for *SSLContext* were added. | |
+--------------------------------------------------------------------------------------------------------------+----------------+
| Added *SSLContext.post_handshake_auth* to enable and *ssl.SSLSocket.verify_client_post_handshake()* to | |
| initiate TLS 1.3 post-handshake authentication. | |
+--------------------------------------------------------------------------------------------------------------+----------------+
| `struct <https://docs.python.org/3.6/whatsnew/3.6.html#struct>`_ | |
+--------------------------------------------------------------------------------------------------------------+----------------+
| now supports IEEE 754 half-precision floats via the 'e' format specifier. | |
+--------------------------------------------------------------------------------------------------------------+----------------+
| `sys <https://docs.python.org/3.6/whatsnew/3.6.html#sys>`_ | |
+--------------------------------------------------------------------------------------------------------------+----------------+
| The new *getfilesystemencodeerrors()* function returns the name of the error mode used to convert between | |
| Unicode filenames and bytes filenames. | |
+--------------------------------------------------------------------------------------------------------------+----------------+
| `zlib <https://docs.python.org/3.6/whatsnew/3.6.html#zlib>`_ | |
+--------------------------------------------------------------------------------------------------------------+----------------+
| The *compress()* and *decompress()* functions now accept keyword arguments | |
+--------------------------------------------------------------------------------------------------------------+----------------+