Python 3.4 的新功能 ¶

摘要 – 发行亮点 ¶

新句法特征：

• No new syntax features were added in Python 3.4.

Other new features:

• pip should always be available ( PEP 453 ).

• Newly created file descriptors are non-inheritable ( PEP 446 ).

• command line option for isolated mode ( bpo-16499 ).

• improvements in the handling of codecs that are not text encodings (multiple issues).

• A ModuleSpec Type for the Import System ( PEP 451 ). (Affects importer authors.)

• The marshal format has been made more compact and efficient ( bpo-16475 ).

新的库模块：

• asyncio : New provisional API for asynchronous IO ( PEP 3156 ).

• ensurepip : Bootstrapping the pip installer ( PEP 453 ).

• enum : Support for enumeration types ( PEP 435 ).

• pathlib : Object-oriented filesystem paths ( PEP 428 ).

• selectors : High-level and efficient I/O multiplexing , built upon the select module primitives (part of PEP 3156 ).

• statistics : A basic numerically stable statistics library ( PEP 450 ).

• tracemalloc : Trace Python memory allocations ( PEP 454 ).

Significantly improved library modules:

• Single-dispatch generic functions in functools ( PEP 443 ).

• New pickle protocol 4 ( PEP 3154 ).

• multiprocessing 现在拥有 an option to avoid using os.fork on Unix ( bpo-8713 ).

• email has a new submodule, contentmanager , and a new Message subclass ( EmailMessage ) that simplify MIME handling ( bpo-18891 ).

• The inspect and pydoc modules are now capable of correct introspection of a much wider variety of callable objects, which improves the output of the Python help() system.

• The ipaddress module API has been declared stable

Security improvements:

• Secure and interchangeable hash algorithm ( PEP 456 ).

• Make newly created file descriptors non-inheritable ( PEP 446 ) to avoid leaking file descriptors to child processes.

• New command line option for isolated mode , ( bpo-16499 ).

• multiprocessing 现在拥有 an option to avoid using os.fork on Unix . spawn and forkserver are more secure because they avoid sharing data with child processes.

• multiprocessing child processes on Windows no longer inherit all of the parent’s inheritable handles, only the necessary ones.

• 新的 hashlib.pbkdf2_hmac() function provides the PKCS#5 password-based key derivation function 2 .

• TLSv1.1 and TLSv1.2 support for ssl .

• Retrieving certificates from the Windows system cert store support for ssl .

• Server-side SNI (Server Name Indication) support for ssl .

• The ssl.SSLContext 类拥有 lot of improvements .

• All modules in the standard library that support SSL now support server certificate verification, including hostname matching ( ssl.match_hostname() ) and CRLs (Certificate Revocation lists, see ssl.SSLContext.load_verify_locations() ).

CPython 实现改进：

• Safe object finalization ( PEP 442 ).

• Leveraging PEP 442 , in most cases module globals are no longer set to None during finalization ( bpo-18214 ).

• Configurable memory allocators ( PEP 445 ).

• Argument Clinic ( PEP 436 ).

Please read on for a comprehensive list of user-facing changes, including many other smaller improvements, CPython optimizations, deprecations, and potential porting issues.

新特征 ¶

>>> b"abcdef".decode("hex")
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
LookupError: 'hex' is not a text encoding; use codecs.decode() to handle arbitrary codecs
>>> "hello".encode("rot13")
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
LookupError: 'rot13' is not a text encoding; use codecs.encode() to handle arbitrary codecs
>>> open("foo.txt", encoding="hex")
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
LookupError: 'hex' is not a text encoding; use codecs.open() to handle arbitrary codecs