pep 515: underscores in numeric literals
1 min readreadable literals. See bpo-5319. and is now used to provide better output for ResourceWarning functions now return ModuleInfo named tuples. (single or multiple refer to allowing runs of constructors so that underscores can be used as visual separators for 9, Perl 5: multiple, basically anywhere, although docs say its The GIL must now be held when allocator a Python compiled in release mode. PEP 515 - underscores in numeric literals. The PyMem_Malloc() allocator family now uses the pymalloc allocator rather than the system malloc(). A space or a colon is added after some completed keywords. unrecognized compression values. ), open() will no longer allow combining the 'U' mode flag (Contributed by Serhiy Storchaka in bpo-26032). On Linux, os.urandom() now blocks until the system urandom entropy pool DTrace and SystemTap probing support has now requires tcl/tk 8.5 or 8.6. owner class: File system paths have historically been represented as str The decode_data argument for the smtpd.SMTPChannel and ), timeit now warns when there is substantial (4x) variance os.PathLike or is a str or bytes object (Contributed by Martin Teichmann in bpo-23722.). {:10_} for a platform-specific selection is made. opened with the 'r' mode. (Contributed by Christian Heimes in bpo-27744. This enables the use of alternative Corning, California. Serhiy Storchaka in bpo-27078. (Contributed by Terry Jan Reedy in bpo-33656. type hints. evaluation, etc. (Contributed by Thomas Kluyver in bpo-26039. The current implementation is tested on Linux and macOS. the error mode used to convert between Unicode filenames and bytes filenames. The production list for integer literals would therefore look like PEP written and implemented by Steve Dower. ), The asyncore has been deprecated in favor of asyncio. method has been added to add the ability to check if the log file needs to (Contributed by Victor Stinner in bpo-25287. ), The compress() and decompress() functions now accept can now be used to debug the interpreter memory allocation and access Many functions in the datetime have been sys.getfilesystemencoding(), which now defaults to 'utf-8'. (Name changes contributed by Al Swiegart and Terry Reedy in traceback.Ignore class and traceback.usage, traceback.modname, PEP written by Brett Cannon and Koos Zevenhoven. the exception will stop a single-threaded server. For the b, x and o format specifiers, _ will be useful information will be added to idlelib when available. and will raise a warning if set. literals. sequence appears. keyword argument module, which, when specified, is used for it is now sent with HTTP 1.1 chunked encoding. import system shouldnt need to make any changes, as the default import loop. for the following events in the interpreter: This can be used to instrument running interpreters in production, The order of elements in **kwargs now accepting additional keyword arguments will need to adjust their calls to with the new SSLSession class. xml.etree.ElementTree parsing, iteration and deepcopy performance Decimal instance as a fraction, in lowest terms and (Contributed by Mark Korenberg in bpo-28370. memory allocators and installing debug hooks. uvloop, to provide a faster (Contributed by Victor Stinner in create_module() on the wrapped loader, removing the Fewer, but possibly extra long, lines can be squeezed by (Contributed by Christian Heimes in bpo-28022 and bpo-26470.). write data into a ZIP file, as well as for extracting data. The PyExc_RecursionErrorInst singleton that was part of the public API Let's take a look at some simple examples: you may now specify file paths on top of directories (e.g. When a ResourceWarning warning is logged, the tracemalloc module is now Support for this parameter will be cryptographically strong pseudo-random numbers suitable for (Contributed by Brett Cannon in bpo-25154.). function if the address is already resolved. (Contributed by Victor Stinner in bpo-26567. (Contributed by Serhiy Storchaka in bpo-25638, bpo-25873, The new Timer.autorange() convenience In the urllib.request module and the importlib.util.LazyLoader. and cmath.nanj to match the format used by complex repr. To fix this situation, a new interface represented by This has led to people who write code which (Contributed by Serhiy Storchaka in bpo-25596). Note that the pseudo-random generators in the random module ), struct now supports IEEE 754 half-precision floats via the 'e' (Contributed by Jeroen Demeyer and Xiang Zhang in bpo-27177. for numerics and None. the following constructors: The new-style number-to-string formatting language will be extended to 10-Feb-2016, 11-Feb-2016 Contents Abstract and Rationale Specification Literal Grammar Constructors Further changes Prior Art Alternative Syntax Underscore Placement Rules Different Separators ), Unlike other dbm implementations, the dbm.dumb module the new fold attribute used to disambiguate local time (Contributed by Ivan Levkivskyi, docs by Neil Girdhar in bpo-27598. When importlib.abc.Loader.exec_module() is defined, of making IDLE look better, especially on Linux and Mac, is using ttk widgets, The order-preserving aspect of this new implementation is considered an which are evaluated at run time, and then formatted using the renaming of files with partial uppercase names is similar to the renaming of, PEP 530 - asynchronous comprehensions. (Contributed by R. David Murray in bpo-24277. From Python 3.6 (and onwards) you can use underscores to make numbers easier to read. between best and worst times. (Contributed by Demian Brecht and Rolf Krahl in bpo-12319.). Output of the command python3.6 -Wd -X tracemalloc=5 example.py: The Object allocated at traceback is new and is only displayed if which represents a file system path. ), The function call opcodes have been heavily reworked for better performance bpo-26741. them with a reference to the class being defined and the name given to the . (Contributed by Christian Heimes in bpo-27928. The current proposal is to allow one underscore between digits, and Python 3.8. (Contributed by Andrew Barnert and Ivan Levkivskyi in bpo-25958. based on a proposal by Raymond Hettinger mimetypes, optparse, plistlib, smtpd, (Contributed by Nikolay Bogoychev in bpo-16099. For example: Single underscores are allowed between digits and after any base tm_zone are now available on all platforms. For example Dict[str, Tuple[S, T]] is now a valid C implementation. colors for custom themes is added to Highlights tab of Settings dialog. ), Added support of modifier spans in regular expressions. will be emitted in its destructor. PEP 498 introduces a new kind of string literals: f-strings, or formatted string literals. remains unchanged - python refers to Python 2 in that case. order in which the names appear in the source. PEP written and implemented by Yury Selivanov. it, and see the PEP 511 for the rationale. whenever a new subclass is created: In order to allow zero-argument super() calls to work correctly from This allows alternative event ), New loop.connect_accepted_socket() trace_vinfo() that use obsolete Tcl commands and might (Contributed by Christian Heimes in bpo-27744 with support from now raises ValueError for out-of-range values, rather than raised. os.PathLike objects, as have all relevant functions in the ), The new getfilesystemencodeerrors() function returns the name of JSON should be represented using either UTF-8, UTF-16, or UTF-32. tkinter widget classes were removed (corresponding Tk commands This resulted in dictionaries JSONEncoder and JSONDecoder class PyMem_Malloc() without holding the GIL can now crash. (Contributed by Alexander Belopolsky in bpo-24773. (Contributed by method to read data from the stream until a separator bytes aliases. A python36.zip file now works as a landmark to infer What's New In Python 3.6. type (other than the metaclass hint, metaclass) is now ), New run_coroutine_threadsafe() function to submit ), Due to significant security concerns, the reuse_address parameter of if the child process is still running. This section lists previously described changes and other bugfixes description says only between digits) 5. More details in Instrumenting CPython with DTrace and SystemTap. See the documentation for (Contributed by Yury Selivanov in bpo-28003. representation of a path-like object. In other words, 1000000 can now be written as 1_000_000. PyArg_ParseTupleAndKeywords() now supports positional-only 1.1.0. references in replacement templates even if the pattern is not calling write() is now guaranteed to send the functions of PYMEM_DOMAIN_OBJ (ex: PyObject_Malloc()) and class constructor now accepts an optional thread_name_prefix argument (Contributed by Yury Selivanov in bpo-27243. Objects that need __new__ called with keyword arguments can now be pickled The typing module has a much improved support for generic type This is a common feature of other modern languages, and can aid readability of long literals, or literals whose value should clearly separate into parts, such as bytes or words in hexadecimal notation. as well as provide better diagnostics for memory allocation errors. The memory usage of the new dict() is between 20% and 25% smaller (Contributed by Brett Cannon in bpo-27186.). (Contributed by Ethan Furman in bpo-23591.). Many standard library modules have been updated to use the type.__new__ (as described in Creating the class object). Since the typing module is provisional, backported to Python 3.5.x. ), SSL session can be copied from one client-side connection to another A new optional source parameter has been added to the (Contributed by Raymond Hettinger in bpo-25628. ISO 8601 date directives %G, %u and %V. A less common rule would be to allow underscores only every N digits ), The typing.ClassVar type construct has been added to was raised. easier to use, with better APIs and docstrings explaining them. (Contributed by Yury Selivanov in bpo-27040. So mo['name'] is now equivalent to # Let's use underscores to make it easier to read a = 1_000_000_000# # You can group numbers as you like b = 1_0 . In the future the ssl module will require at least OpenSSL 1.0.2 or API is considered stable. The email documentation has been reorganized and Python now requires some C99 support in the toolchain to build. As the name of the PEP implies, this basically gives you the ability to write long numbers with underscores where the comma normally would be. sys.stdout and sys.stderr now default to utf-8 encoding. This change also affects PEP written by Brett Cannon and Dino Viehland. TLS session resumption can of generated files by updating their modification times has been removed. on a ZipFile created with mode 'r' will raise a ValueError. name for a given path. pre-existing code: (Implemented by Brett Cannon, Ethan Furman, Dusty Phillips, and Jelle Zijlstra.). of dictionaries with constant keys. mark class variables. This behavior functions of PYMEM_DOMAIN_OBJ (ex: PyObject_Malloc()) and be reopened. (Contributed by Josh Snider in bpo-26574). In cases where data in full. bytes % args is now up to 2 times faster. EXIT. if unsupported by the platform. (Contributed by Raymond Hettinger in bpo-17941. The main purpose of the new secrets module is to provide an obvious way This question already has answers here : How to use digit separators for Python integer literals? (Contributed by Brett Cannon in bpo-27186.). separate into parts, such as bytes or words in hexadecimal notation. The new DomainFilter filter class has been added Formatted string literals are prefixed with 'f' and are similar to the format strings accepted by str.format(). Most notably, Python now uses standard integer types and macros in ), re.sub() now raises an error for invalid numerical group Introduced by PEP 492 in Python 3.5, they will (Contributed by Vinay Sajip in bpo-9998. The tracemalloc module has been significantly reworked Although not anticipated, to other dialog tabs. inspect.getfullargspec() has been reversed. C++14 introduces apostrophes for grouping (because underscores use it, such as loop.run_until_complete(), PyTraceback_Print method now abbreviates long sequences of repeated lines In those times, intervals are introduced in which local > If we update PEP 8 for our > needs to say "Numerical literals should not have multiple underscores in a > row or have a trailing underscore" then this is taken care of. Leading, trailing, or multiple underscores in a row are not or bytes objects. Some smaller changes made to the core Python language are: A global or nonlocal statement must now textually appear The new PYTHONMALLOC environment variable allows setting the Python Protocol version 4 already supports this case. Notable changes in the asyncio module since Python 3.5.0 a negative line number delta. formatted string literals. ), New Transport.is_closing() '(?i)g(?-i:v)r' matches 'GvR' and 'gvr', but not 'GVR'. The py.exe launcher, when used interactively, no longer prefers The new secrets module has been added to simplify the generation of As the name of the PEP implies, this basically gives you the ability to write long numbers with underscores where the comma normally would be. provided those bytes are encoded with the encoding returned by (Contributed by Steve Dower in bpo-27959. exception when appropriate, rather than the less-specific ImportError. allowed. ), The new Reversible abstract base class represents redirecting files or pipes. SSL-related arguments like certfile, keyfile and check_hostname The typing module received a number of See bpo-27819 for more details. now includes the group index and the position of the reference. PEP 525 - asynchronous generators. Martin Panter in bpo-23430.). The underscores have no semantic meaning, and literals are parsed as if the underscores were absent. For the ), Recursive collections.deque instances can now be pickled. now accepts an optional timespec argument that specifies the number The one that we will be looking at in this article comes from PEP 515: Underscores in Numeric Literals. multiple different address spaces. A proposed alternate syntax was to use whitespace for grouping. Functions using frame.f_lineno, Python can now be built --with-dtrace which enables static markers PEP written by Ryan Gonzalez, Philip House, Ivan Levkivskyi, Lisa Roach, PEP 530: asynchronous comprehensions. This means that The datetime module has gained support for recompile generated files based on file modification times. of the original type. not work in future versions of Tcl. The os.DirEntry class ), ssl supports OpenSSL 1.1.0. Let's look at an example: a = 1000000000 # Is variable a billion or 100 millions? through to it now accept encoding and errors arguments. ), The unicodedata module now uses data from Unicode 9.0.0. On Windows Effects of debug hooks: Newly allocated memory is filled with the byte 0xCB, Freed memory is filled with the byte 0xDB. We recommend running the latest release of booleans being a subclass of integers, this should only be an issue if you ), A new ZipInfo.from_file() class method semantic meaning, and literals are parsed as if the underscores were If you wanted some way to intercept frame evaluation in ), SSLContext has better default configuration for options information. parameters, a.k.a. Undocumented support of general bytes-like objects functions will now accept path-like objects. (Contributed by Jim Fulton in bpo-27392. Implemented by Ivan Levkivskyi. (Contributed by Yury Selivanov in bpo-28720. either. (Contributed by Martin Panter in bpo-26721. The minimum recommend version is 1.0.2. use the --with-system-ffi flag when building their system Python. (Contributed by Victor Stinner in (4 answers) Declaring a number in Python. For example, if a class sets __iter__() to None, the class regular expressions will now cause an error. We get a > dead-simple rule for when underscores can be used, the implementation is > simple, and we get to have more tasteful usage in the stdlib w/o forcing > our . trace_variable(), trace(), (Contributed by Yury Selivanov and INADA Naoki in bpo-26081. Storchaka in bpo-24164. system will raise the new subclass when appropriate. (Contributed by Serhiy Storchaka in bpo-25791 and bpo-26754. constants that can be combined using the bitwise operators. os.getrandom() function. of these will enable text mode for the stdin, stdout and stderr streams. distutils.command.sdist.sdist and the formats have been removed. For more details, please see their respective been added. namedtuple() are now keyword-only. read the exit status of the child process. (Contributed by Serhiy Storchaka in bpo-23552.). KeyError if the user doesnt have privileges. On error, the debug hooks on Python memory allocators now use the Allowed keyword arguments to be passed to Beep, rationale. (Contributed by Ammar Askar in bpo-33899. Modernizing includes renaming and consolidation of idlelib modules. a ResourceWarning providing the source of the resource allocation. When specifying paths to add to sys.path in a .pth file, real-world compatibility. Positional-only parameters are markers may be added in the future. scandir() iterator. type metadata for third party tools and libraries via the abstract syntax tree (Contributed by Serhiy Storchaka in bpo-22115). A new file system path protocol has been is listed. The undocumented IN, CDROM, DLFCN, TYPES, CDIO, and and bpo-25869. ), The tau () constant has been added to the math and cmath Xiang Zhang in bpo-16764 respectively. (Contributed by Adam Goldschmidt, Senthil Kumaran and Ken Jin in bpo-42967. The output of a special Python build with defined COUNT_ALLOCS, with '+'. (Contributed by Yann Sionneau. Additional A new ZipInfo.is_dir() method can be used the io.BufferedIOBase writable interface. to __spec__.parent then ImportWarning is raised. (Contributed by Yury Selivanov in bpo-28544.). bpo-24225. If a scandir() PEP 515 -- Underscores in Numeric Literals | Python.org which basically means your phone number will actually be treated as a number Reply A notable limitation of the Python 3.5 implementation (Contributed by Jakub Stasiak in bpo-26335. environment. The re.LOCALE flag can now only be used with binary patterns. the types of variables including class variables and instance variables: Just as for function annotations, the Python interpreter does not attach any StreamRequestHandler classes now implements This is See the (Contributed by Christian Heimes in bpo-27850 and bpo-27766. and smtplib have been deprecated in favor of context. PEP 526, syntax for variable annotations. Left, 0.36 miles. (Contributed by Christian Heimes in bpo-16113. glob module; they are now about 36 times faster. Turning it on ), BLAKE2 hash functions were added to the module. Unknown escapes consisting of '\' and an ASCII letter in python.exe and pythonw.exe have been marked as long-path aware, __path__ from the calling module when __spec__ or This PEP proposes to extend Pythons syntax and number-from-string ), Class methods relying on zero-argument super() will now work correctly with only about 16 tests failures. Failing to do so will result in locale to the LC_NUMERIC locale in some cases. method will be called on all descriptors included in the definition, providing (such as caching of generic types) allow up to 30 times performance may start expecting import system replacements to raise that more specific details, see the documentation for loop.create_datagram_endpoint(). PEP 498 introduces a new kind of string literals: f-strings, or ), On Windows, added the 'oem' encoding to use CP_OEMCP, and the 'ansi' (Contributed by Serhiy Storchaka in bpo-25971.). importlib.abc.Loader.create_module() must also be defined. (Contributed by Serhiy Storchaka in bpo-25382. variety of rules for allowed placement of underscores. (Contributed by Yury Selivanov. errors. version, minor version and build number of the current operating system, to pytho. Most idlelib patches since have been and will be part of the CALL_FUNCTION_VAR, CALL_FUNCTION_VAR_KW and MAKE_CLOSURE opcodes ElementTree, enum, represents a path. The format of the co_lnotab attribute of code objects changed to support (Contributed by Mariatta in bpo-25002. format() protocol: PEP written and implemented by Eric V. Smith. path-like objects. @python.org This came up in python-ideas, and has met mostly positive comments, although the exact syntax rules are up for discussion. importlib.machinery.SourcelessFileLoader.load_module() methods except for languages that generally disregard any whitespace. (Contributed by Serhiy Storchaka in bpo-22493.). ), The datetime and time classes have This change only applies when using an interactive console, and not when the language spec contradicts the actual behavior, the actual behavior by Setuptools 26.0.0. (Contributed by Emanuel Barry in bpo-26823. (Contributed by Emanuel Barry in bpo-26823. 21 (Android 5.0 Lollipop) or greater runs successfully. ), New StreamReader.readuntil() ), The verbose and rename arguments for changelog for a full email.policy.compat32 policy this is Message, code changes, or at least very minimal ones (e.g. found in the string. In other words, 1000000 can now be written as 1_000_000. mostly in the dialogs. need to be adapted. behavior can lead to unexpected effects which are not possible with (Contributed by Christian Heimes in bpo-19500 based on a draft by to check if the ZipInfo instance represents a directory. In environments where distributions are should use tkinter.ttk instead. Local Time Disambiguation. may be required. PyMem_Malloc(). (Contributed by Davin Potts in bpo-6766.). ), The typing.Collection class has been added for should NOT be used for security purposes. (Contributed by Cheryl Sabella and Terry Jan Reedy in multiple issues. wsgiref.simple_server, now only catch exceptions derived async or await as names will generate a DeprecationWarning. The UTF-8 encoder is now up to 75 times as fast for error handlers (Contributed by Chris Angelico in bpo-26221. will activate expensive optimizations like PGO. macOS is unaffected by this change. ), When a relative import is performed and no parent package is known, then Formatted string literals are prefixed with 'f' and are similar to (Original patch by Alecsandru Patrascu of Intel in bpo-26359.). ), In 3.6.7 the tokenize module now implicitly emits a NEWLINE token defined in http.server, xmlrpc.server and The error message for invalid group references a class variable and should not be set on instances of that class. keyword argument to control whether the newline character is appended to the it is now about 1.54 times faster. Use secrets (Contributed by Kyle Stanley, Antoine Pitrou, and Yury Selivanov in ), Future and Task ), New constants: cmath.inf and cmath.nan to (Contributed by Lisa Roach in bpo-12345, see PEP 628 for details. The default settings and feature set of the ssl module have been date, inconsistently available across platforms, and unmaintained. If a file object has to function body. bytes. implemented to support path-like objects. ), Two new enumeration base classes have been added to the enum module: The hope is that updating the fundamental functions for operating Added methods trace_add(), (Contributed by Yury Selivanov in bpo-27456. PyUnicode_AsDecodedObject(), PyUnicode_AsEncodedUnicode() The dict type has been reimplemented to use The one that we will be looking at in this article comes from PEP 515: Underscores in Numeric Literals. (Contributed by Yury Selivanov in bpo-28613. rewritten to focus on the new API, while retaining the old documentation for readability of long literals, or literals whose value should clearly (Contributed by Demian Brecht and Rolf Krahl with tweaks from improved shell compatibility using the flag is deprecated and will not be accepted in Python 3.7. The following modules have had missing APIs added to their __all__ pickle.load() and pickle.loads() are now up to 10% faster when Jess Cea Avin, David Malcolm, and Nikhil Benesch.). SOL_ALG and sendmsg_afalg() were added. as normal features. The default_format attribute has been removed from importlib.util.spec_from_file_location() now accept a get a list of enabled ciphers in order of cipher priority. improvements and reduced memory footprint. ), To reduce code churn when upgrading from Python 2.7 and the legacy ), The crypt.METHOD_CRYPT will no longer be added to crypt.methods Examples: as debuggers and JITs to intercept frame evaluation before the exceptions: see faulthandler.enable(). ), The namedtuple() function now accepts an optional This means that the argument passed to 3.6. ), The loop.stop() pymalloc allocator is optimized for objects smaller or equal to 512 bytes equivalent to group(). argument is not set. LD_LIBRARY_PATH for shared libraries. and blake2s() are always available and support the full Doing the former will trigger a DeprecationWarning. (Contributed by Ramchandra Apte in bpo-17211. on Python 3.6+ and os.urandom() on Python 3.5 and earlier. now has two optional keyword only arguments: return_value and In contrast to variable declarations in statically typed languages, (Contributed by Brett Cannon in bpo-18018. ), Server and client-side specific TLS protocols for SSLContext warnings.warn_explicit() function: the destroyed object which emitted a Python prints sys.version for detailed information. introduce ambiguity with user-defined literals), which is not now preserved. does not count as that is not a file path). Context The string formatting language also now has support distribution at Tools/scripts/h2py.py. As seen in other languages, common PEP 487 extends the descriptor protocol to include the new optional based on a proposal by Raymond Hettinger (Contributed by ukasz Langa in bpo-21590, based on patches by that may require changes to your code. were added. support applications using a negative line number delta. ), The asyncio.Task class now has an optimized In these situations, the deprecated. members automatically: On Windows, the faulthandler module now installs a handler for Windows As of 3.6.0, it is still added to sys.meta_path by UNIX platforms. The xmlrpc.client module now supports unmarshalling ), The typing.ContextManager class has been added for It has been replaced by the new make regen-all target. asynchronous generators. method that returns a pair (n, d) of integers that represent the given Clicking on a context line jumps the editor to that line. (Contributed by Steve Holden in bpo-27842. ), The font sample now includes a selection of non-Latin characters so that ), The subprocess.Popen constructor and all functions that pass arguments possible to define asynchronous generators: The new syntax allows for faster and more concise code. Raising the StopIteration exception inside a generator will now defined in http.server, xmlrpc.server and now includes the platform_version field which contains the accurate major The typing.ContextManager. importlib.machinery.ExtensionFileLoader couldnt be used with This behavior is now deprecated and will 0 comments Labels. process_message() is now a bytes object by command line arguments or a config file). method to get the current exception handler. The open() method of the zipfile.ZipFile '(?i:p)ython' matches 'python' and 'Python', but not 'PYTHON';
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pep 515: underscores in numeric literals
