Python (язык программирования)

Питон

Парадигма	Мультипарадигмальность : объектно-ориентированная , процедурный ( императивный ), функциональный , структурированный , рефлексивный
Разработано	Гвидо ван Россум
Разработчик	Фонд программного обеспечения Python
Впервые появился	20 февраля 1991 г ( 1991-02-20 )
Стабильная версия	3.12.4  / 6 июня 2024 г ( 6 июня 2024 г. )
Дисциплина набора текста	утка , динамичная , сильная ; optional type annotations (since 3.5, but those hints are ignored, except with unofficial tools)
OS	Tier 1: 64-bit Linux, macOS; 64- and 32-bit Windows 10+ Tier 2: E.g. 32-bit WebAssembly (WASI) Tier 3: 64-bit FreeBSD, iOS; e.g. Raspberry Pi OS Unofficial (or has been known to work): Other Unix-like/BSD variants and e.g. Android 5.0+ (official from Python 3.13 planned) and a few other platforms
License	Python Software Foundation License
Filename extensions	.py, .pyw, .pyz, .pyi, .pyc, .pyd
Website	python.org
Major implementations
CPython, PyPy, Stackless Python, MicroPython, CircuitPython, IronPython, Jython
Dialects
Cython, RPython, Starlark
Influenced by
ABC, Ada, ALGOL 68, APL, C, C++, CLU, Dylan, Haskell, Icon, Lisp, Modula-3, Perl, Standard ML
Influenced
Apache Groovy, Boo, Cobra, CoffeeScript, D, F#, GDScript, Genie, Go, JavaScript, Julia, Mojo, Nim, Ring, Ruby, Swift
Python Programming at Wikibooks

Python — это высокого уровня язык программирования общего назначения . Его философия дизайна подчеркивает читаемость кода за счет использования значительных отступов .

Python является динамически типизированным и собирает мусор . Он поддерживает несколько парадигм программирования , включая структурированное (особенно процедурное ), объектно-ориентированное и функциональное программирование . Его часто называют языком «с батарейками» из-за его обширной стандартной библиотеки .

Гвидо ван Россум начал работать над Python в конце 1980-х годов как преемником языка программирования ABC и впервые выпустил его в 1991 году как Python 0.9.0. Python 2.0 был выпущен в 2000 году. Python 3.0, выпущенный в 2008 году, представлял собой основную версию, не полностью обратно совместимую с более ранними версиями. Python 2.7.18, выпущенный в 2020 году, был последней версией Python 2.

Python consistently ranks as one of the most popular programming languages, and has gained widespread use in the machine learning community.

History

The designer of Python, Guido van Rossum, at OSCON 2006

Main article: History of Python

Python was invented in the late 1980s by Guido van Rossum at Centrum Wiskunde & Informatica (CWI) in the Netherlands as a successor to the ABC programming language, which was inspired by SETL, capable of exception handling and interfacing with the Amoeba operating system. Its implementation began in December 1989. Van Rossum shouldered sole responsibility for the project, as the lead developer, until 12 July 2018, when he announced his "permanent vacation" from his responsibilities as Python's "benevolent dictator for life" (BDFL), a title the Python community bestowed upon him to reflect his long-term commitment as the project's chief decision-maker (he's since come out of retirement and is self-titled "BDFL-emeritus"). In January 2019, active Python core developers elected a five-member Steering Council to lead the project.

Python 2.0 was released on 16 October 2000, with many major new features such as list comprehensions, cycle-detecting garbage collection, reference counting, and Unicode support. Python 3.0, released on 3 December 2008, with many of its major features backported to Python 2.6.x and 2.7.x. Releases of Python 3 include the 2to3 utility, which automates the translation of Python 2 code to Python 3.

Python 2.7's end-of-life was initially set for 2015, then postponed to 2020 out of concern that a large body of existing code could not easily be forward-ported to Python 3. No further security patches or other improvements will be released for it. Currently only 3.8 and later are supported (2023 security issues were fixed in e.g. 3.7.17, the final 3.7.x release). While Python 2.7 and older is officially unsupported, a different unofficial Python implementation, PyPy, continues to support Python 2, i.e. "2.7.18+" (plus 3.9 and 3.10), with the plus meaning (at least some) "backported security updates".

In 2021 (and again twice in 2022), security updates were expedited, since all Python versions were insecure (including 2.7) because of security issues leading to possible remote code execution and web-cache poisoning. In 2022, Python 3.10.4 and 3.9.12 were expedited and 3.8.13, because of many security issues. When Python 3.9.13 was released in May 2022, it was announced that the 3.9 series (joining the older series 3.8 and 3.7) would only receive security fixes in the future. On 7 September 2022, four new releases were made due to a potential denial-of-service attack: 3.10.7, 3.9.14, 3.8.14, and 3.7.14.

Every Python release since 3.5 has added some syntax to the language. 3.10 added the | union type operator and the match and case keywords (for structural pattern matching statements). 3.11 expanded exception handling functionality. Python 3.12 added the new keyword type.

Notable changes in 3.11 from 3.10 include increased program execution speed and improved error reporting. Python 3.11 claims to be between 10 and 60% faster than Python 3.10, and Python 3.12 adds another 5% on top of that. It also has improved error messages, and many other changes.

As of April 2024, Python 3.12 is the stable release, and 3.12 is the only version with active (as opposed to just security) support.

Since 27 June 2023, Python 3.8 is the oldest supported version of Python (albeit in the 'security support' phase), due to Python 3.7 reaching end-of-life.

Python 3.13 introduced an incremental garbage collector (producing shorter pauses for collection in programs with a lot of objects); an experimental JIT compiler; and removals from the C API. Some standard library modules and many deprecated classes, functions and methods, will be removed in Python 3.15 and or 3.16. Starting with 3.13, it and later versions have 2 years of full support (up from one and a half); followed by 3 years of security support (for same total support as before).

Design philosophy and features

Python is a multi-paradigm programming language. Object-oriented programming and structured programming are fully supported, and many of their features support functional programming and aspect-oriented programming (including metaprogramming and metaobjects). Many other paradigms are supported via extensions, including design by contract and logic programming.

Python uses dynamic typing and a combination of reference counting and a cycle-detecting garbage collector for memory management. It uses dynamic name resolution (late binding), which binds method and variable names during program execution.

Its design offers some support for functional programming in the Lisp tradition. It has filter,mapandreduce functions; list comprehensions, dictionaries, sets, and generator expressions. The standard library has two modules (itertools and functools) that implement functional tools borrowed from Haskell and Standard ML.

Its core philosophy is summarized in the Zen of Python (PEP 20), which includes aphorisms such as:

• Beautiful is better than ugly.
• Explicit is better than implicit.
• Simple is better than complex.
• Complex is better than complicated.
• Readability counts.

However, Python features regularly violate these principles and have received criticism for adding unnecessary language bloat. Responses to these criticisms are that the Zen of Python is a guideline rather than a rule. The addition of some new features had been so controversial that Guido van Rossum resigned as Benevolent Dictator for Life following vitriol over the addition of the assignment expression operator in Python 3.8.

Nevertheless, rather than building all of its functionality into its core, Python was designed to be highly extensible via modules. This compact modularity has made it particularly popular as a means of adding programmable interfaces to existing applications. Van Rossum's vision of a small core language with a large standard library and easily extensible interpreter stemmed from his frustrations with ABC, which espoused the opposite approach.

Python claims to strive for a simpler, less-cluttered syntax and grammar while giving developers a choice in their coding methodology. In contrast to Perl's "there is more than one way to do it" motto, Python embraces a "there should be one—and preferably only one—obvious way to do it." philosophy. In practice, however, Python provides many ways to achieve the same task. There are, for example, at least three ways to format a string literal, with no certainty as to which one a programmer should use. Alex Martelli, a Fellow at the Python Software Foundation and Python book author, wrote: "To describe something as 'clever' is not considered a compliment in the Python culture."

Python's developers usually strive to avoid premature optimization and reject patches to non-critical parts of the CPython reference implementation that would offer marginal increases in speed at the cost of clarity. Execution speed can be improved by moving speed-critical functions to extension modules written in languages such as C, or by using a just-in-time compiler like PyPy. It is also possible to cross-compile to other languages, but it either doesn't provide the full speed-up that might be expected, since Python is a very dynamic language, or a restricted subset of Python is compiled, and possibly semantics are slightly changed.

Python's developers aim for it to be fun to use. This is reflected in its name—a tribute to the British comedy group Monty Python—and in occasionally playful approaches to tutorials and reference materials, such as the use of the terms "spam" and "eggs" (a reference to a Monty Python sketch) in examples, instead of the often-used "foo" and "bar". A common neologism in the Python community is pythonic, which has a wide range of meanings related to program style. "Pythonic" code may use Python idioms well, be natural or show fluency in the language, or conform with Python's minimalist philosophy and emphasis on readability. Code that is difficult to understand or reads like a rough transcription from another programming language is called unpythonic.

Syntax and semantics

Main article: Python syntax and semantics

Python is meant to be an easily readable language. Its formatting is visually uncluttered and often uses English keywords where other languages use punctuation. Unlike many other languages, it does not use curly brackets to delimit blocks, and semicolons after statements are allowed but rarely used. It has fewer syntactic exceptions and special cases than C or Pascal.

Indentation

Main article: Python syntax and semantics § Indentation

Python uses whitespace indentation, rather than curly brackets or keywords, to delimit blocks. An increase in indentation comes after certain statements; a decrease in indentation signifies the end of the current block. Thus, the program's visual structure accurately represents its semantic structure. This feature is sometimes termed the off-side rule. Some other languages use indentation this way; but in most, indentation has no semantic meaning. The recommended indent size is four spaces.

Statements and control flow

Python's statements include:

• The assignment statement, using a single equals sign =
• The if statement, which conditionally executes a block of code, along with else and elif (a contraction of else-if)
• The for statement, which iterates over an iterable object, capturing each element to a local variable for use by the attached block
• The while statement, which executes a block of code as long as its condition is true
• The try statement, which allows exceptions raised in its attached code block to be caught and handled by except clauses (or new syntax except* in Python 3.11 for exception groups); it also ensures that clean-up code in a finally block is always run regardless of how the block exits
• The raise statement, used to raise a specified exception or re-raise a caught exception
• The class statement, which executes a block of code and attaches its local namespace to a class, for use in object-oriented programming
• The def statement, which defines a function or method
• The with statement, which encloses a code block within a context manager (for example, acquiring a lock before it is run, then releasing the lock; or opening and closing a file), allowing resource-acquisition-is-initialization (RAII)-like behavior and replacing a common try/finally idiom
• The break statement, which exits a loop
• The continue statement, which skips the rest of the current iteration and continues with the next
• The del statement, which removes a variable—deleting the reference from the name to the value, and producing an error if the variable is referred to before it is redefined
• The pass statement, serving as a NOP, syntactically needed to create an empty code block
• The assert statement, used in debugging to check for conditions that should apply
• The yield statement, which returns a value from a generator function (and also an operator); used to implement coroutines
• The return statement, used to return a value from a function
• The import and from statements, used to import modules whose functions or variables can be used in the current program
• The match and case statements, an analog of the switch statement construct, that compares an expression against one or more cases as a control-of-flow measure.

The assignment statement (=) binds a name as a reference to a separate, dynamically allocated object. Variables may subsequently be rebound at any time to any object. In Python, a variable name is a generic reference holder without a fixed data type; however, it always refers to some object with a type. This is called dynamic typing—in contrast to statically-typed languages, where each variable may contain only a value of a certain type.

Python does not support tail call optimization or first-class continuations, and, according to Van Rossum, it never will. However, better support for coroutine-like functionality is provided by extending Python's generators. Before 2.5, generators were lazy iterators; data was passed unidirectionally out of the generator. From Python 2.5 on, it is possible to pass data back into a generator function; and from version 3.3, it can be passed through multiple stack levels.

Expressions

Python's expressions include:

• The +, -, and * operators for mathematical addition, subtraction, and multiplication are similar to other languages, but the behavior of division differs. There are two types of divisions in Python: floor division (or integer division) // and floating-point/division. Python uses the ** operator for exponentiation.
• Python uses the + operator for string concatenation. Python uses the * operator for duplicating a string a specified number of times.
• The @ infix operator. It is intended to be used by libraries such as NumPy for matrix multiplication.
• The syntax :=, called the "walrus operator", was introduced in Python 3.8. It assigns values to variables as part of a larger expression.
• In Python, == compares by value. Python's is operator may be used to compare object identities (comparison by reference), and comparisons may be chained—for example, a <= b <= c.
• Python uses and, or, and not as Boolean operators.
• Python has a type of expression named a list comprehension, and a more general expression named a generator expression.
• Anonymous functions are implemented using lambda expressions; however, there may be only one expression in each body.
• Conditional expressions are written as x if c else y (different in order of operands from the c ? x : y operator common to many other languages).
• Python makes a distinction between lists and tuples. Lists are written as [1, 2, 3], are mutable, and cannot be used as the keys of dictionaries (dictionary keys must be immutable in Python). Tuples, written as (1, 2, 3), are immutable and thus can be used as keys of dictionaries, provided all of the tuple's elements are immutable. The + operator can be used to concatenate two tuples, which does not directly modify their contents, but produces a new tuple containing the elements of both. Thus, given the variable t initially equal to (1, 2, 3), executing t = t + (4, 5) first evaluates t + (4, 5), which yields (1, 2, 3, 4, 5), which is then assigned back to t—thereby effectively "modifying the contents" of t while conforming to the immutable nature of tuple objects. Parentheses are optional for tuples in unambiguous contexts.
• Python features sequence unpacking where multiple expressions, each evaluating to anything that can be assigned (to a variable, writable property, etc.) are associated in an identical manner to that forming tuple literals—and, as a whole, are put on the left-hand side of the equal sign in an assignment statement. The statement expects an iterable object on the right-hand side of the equal sign that produces the same number of values as the provided writable expressions; when iterated through them, it assigns each of the produced values to the corresponding expression on the left.
• Python has a "string format" operator % that functions analogously to printf format strings in C—e.g. "spam=%s eggs=%d" % ("blah", 2) evaluates to "spam=blah eggs=2". In Python 2.6+ and 3+, this was supplemented by the format() method of the str class, e.g. "spam={0} eggs={1}".format("blah", 2). Python 3.6 added "f-strings": spam = "blah"; eggs = 2; f'spam={spam} eggs={eggs}'.
• Strings in Python can be concatenated by "adding" them (with the same operator as for adding integers and floats), e.g. "spam" + "eggs" returns "spameggs". If strings contain numbers, they are added as strings rather than integers, e.g. "2" + "2" returns "22".
• Python has various string literals:
  • Delimited by single or double quotes; unlike in Unix shells, Perl, and Perl-influenced languages, single and double quotes work the same. Both use the backslash (\) as an escape character. String interpolation became available in Python 3.6 as "formatted string literals".
  • Triple-quoted (beginning and ending with three single or double quotes), which may span multiple lines and function like here documents in shells, Perl, and Ruby.
  • Raw string varieties, denoted by prefixing the string literal with r. Escape sequences are not interpreted; hence raw strings are useful where literal backslashes are common, such as regular expressions and Windows-style paths. (Compare "@-quoting" in C#.)
• Python has array index and array slicing expressions in lists, denoted as a[key], a[start:stop] or a[start:stop:step]. Indexes are zero-based, and negative indexes are relative to the end. Slices take elements from the start index up to, but not including, the stop index. The third slice parameter, called step or stride, allows elements to be skipped and reversed. Slice indexes may be omitted—for example, a[:] returns a copy of the entire list. Each element of a slice is a shallow copy.

In Python, a distinction between expressions and statements is rigidly enforced, in contrast to languages such as Common Lisp, Scheme, or Ruby. This leads to duplicating some functionality. For example:

• List comprehensions vs. for-loops
• Conditional expressions vs. if blocks
• The eval() vs. exec() built-in functions (in Python 2, exec is a statement); the former is for expressions, the latter is for statements

Statements cannot be a part of an expression—so list and other comprehensions or lambda expressions, all being expressions, cannot contain statements. A particular case is that an assignment statement such as a = 1 cannot form part of the conditional expression of a conditional statement.

Methods

Methods on objects are functions attached to the object's class; the syntax instance.method(argument) is, for normal methods and functions, syntactic sugar for Class.method(instance, argument). Python methods have an explicit self parameter to access instance data, in contrast to the implicit self (or this) in some other object-oriented programming languages (e.g., C++, Java, Objective-C, Ruby). Python also provides methods, often called dunder methods (due to their names beginning and ending with double-underscores), to allow user-defined classes to modify how they are handled by native operations including length, comparison, in arithmetic operations and type conversion.

Typing

The standard type hierarchy in Python 3

Python uses duck typing and has typed objects but untyped variable names. Type constraints are not checked at compile time; rather, operations on an object may fail, signifying that it is not of a suitable type. Despite being dynamically typed, Python is strongly typed, forbidding operations that are not well-defined (for example, adding a number to a string) rather than silently attempting to make sense of them.

Python allows programmers to define their own types using classes, most often used for object-oriented programming. New instances of classes are constructed by calling the class (for example, SpamClass() or EggsClass()), and the classes are instances of the metaclass type (itself an instance of itself), allowing metaprogramming and reflection.

Before version 3.0, Python had two kinds of classes (both using the same syntax): old-style and new-style; current Python versions only support the semantics of the new style.

Python supports optional type annotations. These annotations are not enforced by the language, but may be used by external tools such as mypy to catch errors. Mypy also supports a Python compiler called mypyc, which leverages type annotations for optimization.

Summary of Python 3's built-in types

Type	Mutability	Description	Syntax examples
bool	immutable	Boolean value	True False
bytearray	mutable	Sequence of bytes	bytearray(b'Some ASCII') bytearray(b"Some ASCII") bytearray([119, 105, 107, 105])
bytes	immutable	Sequence of bytes	b'Some ASCII' b"Some ASCII" bytes([119, 105, 107, 105])
complex	immutable	Complex number with real and imaginary parts	3+2.7j 3 + 2.7j
dict	mutable	Associative array (or dictionary) of key and value pairs; can contain mixed types (keys and values), keys must be a hashable type	{'key1': 1.0, 3: False} {}
types.EllipsisType	immutable	An ellipsis placeholder to be used as an index in NumPy arrays	... Ellipsis
float	immutable	Double-precision floating-point number. The precision is machine-dependent but in practice is generally implemented as a 64-bit IEEE 754 number with 53 bits of precision.	1.33333
frozenset	immutable	Unordered set, contains no duplicates; can contain mixed types, if hashable	frozenset([4.0, 'string', True])
int	immutable	Integer of unlimited magnitude	42
list	mutable	List, can contain mixed types	[4.0, 'string', True] []
types.NoneType	immutable	An object representing the absence of a value, often called null in other languages	None
types.NotImplementedType	immutable	A placeholder that can be returned from overloaded operators to indicate unsupported operand types.	NotImplemented
range	immutable	An immutable sequence of numbers commonly used for looping a specific number of times in for loops	range(−1, 10) range(10, −5, −2)
set	mutable	Unordered set, contains no duplicates; can contain mixed types, if hashable	{4.0, 'string', True} set()
str	immutable	A character string: sequence of Unicode codepoints	'Wikipedia' "Wikipedia" """Spanning multiple lines""" Spanning multiple lines
tuple	immutable	Can contain mixed types	(4.0, 'string', True) ('single element',) ()

Arithmetic operations

Python has the usual symbols for arithmetic operators (+, -, *, /), the floor division operator // and the modulo operation % (where the remainder can be negative, e.g. 4 % -3 == -2). It also has ** for exponentiation, e.g. 5**3 == 125 and 9**0.5 == 3.0, and a matrix‑multiplication operator @ . These operators work like in traditional math; with the same precedence rules, the operators infix (+ and - can also be unary to represent positive and negative numbers respectively).

The division between integers produces floating-point results. The behavior of division has changed significantly over time:

• Current Python (i.e. since 3.0) changed / to always be floating-point division, e.g. 5/2 == 2.5.
• The floor division // operator was introduced. So 7//3 == 2, -7//3 == -3, 7.5//3 == 2.0 and -7.5//3 == -3.0. Adding from __future__ import division causes a module used in Python 2.7 to use Python 3.0 rules for division (see above).

In Python terms, / is true division (or simply division), and // is floor division. / before version 3.0 is classic division.

Rounding towards negative infinity, though different from most languages, adds consistency. For instance, it means that the equation (a + b)//b == a//b + 1 is always true. It also means that the equation b*(a//b) + a%b == a is valid for both positive and negative values of a. However, maintaining the validity of this equation means that while the result of a%b is, as expected, in the half-open interval [0, b), where b is a positive integer, it has to lie in the interval (b, 0] when b is negative.

Python provides a round function for rounding a float to the nearest integer. For tie-breaking, Python 3 uses round to even: round(1.5) and round(2.5) both produce 2. Versions before 3 used round-away-from-zero: round(0.5) is 1.0, round(-0.5) is −1.0.

Python allows Boolean expressions with multiple equality relations in a manner that is consistent with general use in mathematics. For example, the expression a < b < c tests whether a is less than b and b is less than c. C-derived languages interpret this expression differently: in C, the expression would first evaluate a < b, resulting in 0 or 1, and that result would then be compared with c.

Python uses arbitrary-precision arithmetic for all integer operations. The Decimal type/class in the decimal module provides decimal floating-point numbers to a pre-defined arbitrary precision and several rounding modes. The Fraction class in the fractions module provides arbitrary precision for rational numbers.

Due to Python's extensive mathematics library, and the third-party library NumPy that further extends the native capabilities, it is frequently used as a scientific scripting language to aid in problems such as numerical data processing and manipulation.

Programming examples

"Hello, World!" program:

print('Hello, world!')

Program to calculate the factorial of a positive integer:

n = int(input('Type a number, and its factorial will be printed: '))

if n < 0:
    raise ValueError('You must enter a non-negative integer')

factorial = 1
for i in range(2, n + 1):
    factorial *= i

print(factorial)

Libraries

Python's large standard library provides tools suited to many tasks and is commonly cited as one of its greatest strengths. For Internet-facing applications, many standard formats and protocols such as MIME and HTTP are supported. It includes modules for creating graphical user interfaces, connecting to relational databases, generating pseudorandom numbers, arithmetic with arbitrary-precision decimals, manipulating regular expressions, and unit testing.

Some parts of the standard library are covered by specifications—for example, the Web Server Gateway Interface (WSGI) implementation wsgiref follows PEP 333—but most are specified by their code, internal documentation, and test suites. However, because most of the standard library is cross-platform Python code, only a few modules need altering or rewriting for variant implementations.

As of 17 March 2024, the Python Package Index (PyPI), the official repository for third-party Python software, contains over 523,000 packages with a wide range of functionality, including:

• Automation
• Data analytics
• Databases
• Documentation
• Graphical user interfaces
• Image processing
• Machine learning
• Mobile apps
• Multimedia
• Computer networking
• Scientific computing
• System administration
• Test frameworks
• Text processing
• Web frameworks
• Web scraping

Development environments

See also: Comparison of integrated development environments § Python

Most Python implementations (including CPython) include a read–eval–print loop (REPL), permitting them to function as a command line interpreter for which users enter statements sequentially and receive results immediately.

Python also comes with an Integrated development environment (IDE) called IDLE, which is more beginner-oriented.

Other shells, including IDLE and IPython, add further abilities such as improved auto-completion, session state retention, and syntax highlighting.

As well as standard desktop integrated development environments including PyCharm, IntelliJ Idea, Visual Studio Code etc, there are web browser-based IDEs, including SageMath, for developing science- and math-related programs; PythonAnywhere, a browser-based IDE and hosting environment; and Canopy IDE, a commercial IDE emphasizing scientific computing.

Implementations

See also: List of Python software § Python implementations

Reference implementation

CPython is the reference implementation of Python. It is written in C, meeting the C89 standard (Python 3.11 uses C11) with several select C99 features. CPython includes its own C extensions, but third-party extensions are not limited to older C versions—e.g. they can be implemented with C11 or C++. CPython compiles Python programs into an intermediate bytecode which is then executed by its virtual machine. CPython is distributed with a large standard library written in a mixture of C and native Python, and is available for many platforms, including Windows (starting with Python 3.9, the Python installer deliberately fails to install on Windows 7 and 8; Windows XP was supported until Python 3.5) and most modern Unix-like systems, including macOS (and Apple M1 Macs, since Python 3.9.1, with experimental installer), with unofficial support for VMS. Platform portability was one of its earliest priorities. (During Python 1 and 2 development, even OS/2 and Solaris were supported, but support has since been dropped for many platforms.)

Python, since 3.7, only supports operating systems with multi-threading support.

Other implementations

• PyPy is a fast, compliant interpreter of Python 2.7 and 3.8. Its just-in-time compiler often brings a significant speed improvement over CPython, but some libraries written in C cannot be used with it.
• Stackless Python is a significant fork of CPython that implements microthreads; it does not use the call stack in the same way, thus allowing massively concurrent programs. PyPy also has a stackless version.
• MicroPython and CircuitPython are Python 3 variants optimized for microcontrollers, including Lego Mindstorms EV3.
• Pyston is a variant of the Python runtime that uses just-in-time compilation to speed up the execution of Python programs.
• Cinder is a performance-oriented fork of CPython 3.8 that contains a number of optimizations, including bytecode inline caching, eager evaluation of coroutines, a method-at-a-time JIT, and an experimental bytecode compiler.
• Snek Embedded Computing Language (compatible with e.g. 8-bit AVR microcontrollers such as ATmega 328P-based Arduino, as well as larger ones compatible with MicroPython) "is Python-inspired, but it is not Python. It is possible to write Snek programs that run under a full Python system, but most Python programs will not run under Snek." It is an imperative language not including OOP / classes, unlike Python, and simplifying to one number type with 32-bit single-precision (similar to JavaScript, except smaller).

Unsupported implementations

Other just-in-time Python compilers have been developed, but are now unsupported:

• Google began a project named Unladen Swallow in 2009, with the aim of speeding up the Python interpreter five-fold by using the LLVM, and of improving its multithreading ability to scale to thousands of cores, while ordinary implementations suffer from the global interpreter lock.
• Psyco is a discontinued just-in-time specializing compiler that integrates with CPython and transforms bytecode to machine code at runtime. The emitted code is specialized for certain data types and is faster than the standard Python code. Psyco does not support Python 2.7 or later.
• PyS60 was a Python 2 interpreter for Series 60 mobile phones released by Nokia in 2005. It implemented many of the modules from the standard library and some additional modules for integrating with the Symbian operating system. The Nokia N900 also supports Python with GTK widget libraries, enabling programs to be written and run on the target device.

Cross-compilers to other languages

There are several compilers/transpilers to high-level object languages, with either unrestricted Python, a restricted subset of Python, or a language similar to Python as the source language:

• Brython, Transcrypt and Pyjs (latest release in 2012) compile Python to JavaScript.
• Codon compiles a subset of statically typed Python to machine code (via LLVM) and supports native multithreading.
• Cython compiles (a superset of) Python to C. The resulting code is also usable with Python via direct C-level API calls into the Python interpreter.
• PyJL compiles/transpiles a subset of Python to "human-readable, maintainable, and high-performance Julia source code". Despite claiming high performance, no tool can claim to do that for arbitrary Python code; i.e. it's known not possible to compile to a faster language or machine code. Unless semantics of Python are changed, but in many cases speedup is possible with few or no changes in the Python code. The faster Julia source code can then be used from Python, or compiled to machine code, and based that way.
• Nuitka compiles Python into C.
• Numba uses LLVM to compile a subset of Python to machine code.
• Pythran compiles a subset of Python 3 to C++ (C++11).
• RPython can be compiled to C, and is used to build the PyPy interpreter of Python.
• The Python → 11l → C++ transpiler compiles a subset of Python 3 to C++ (C++17).

Specialized:

• MyHDL is a Python-based hardware description language (HDL), that converts MyHDL code to Verilog or VHDL code.

Older projects (or not to be used with Python 3.x and latest syntax):

• Google's Grumpy (latest release in 2017) transpiles Python 2 to Go.
• IronPython allows running Python 2.7 programs (and an alpha, released in 2021, is also available for "Python 3.4, although features and behaviors from later versions may be included") on the .NET Common Language Runtime.
• Jython compiles Python 2.7 to Java bytecode, allowing the use of the Java libraries from a Python program.
• Pyrex (latest release in 2010) and Shed Skin (latest release in 2013) compile to C and C++ respectively.

Performance

Performance comparison of various Python implementations on a non-numerical (combinatorial) workload was presented at EuroSciPy '13. Python's performance compared to other programming languages is also benchmarked by The Computer Language Benchmarks Game.

Development

Python's development is conducted largely through the Python Enhancement Proposal (PEP) process, the primary mechanism for proposing major new features, collecting community input on issues, and documenting Python design decisions. Python coding style is covered in PEP 8. Outstanding PEPs are reviewed and commented on by the Python community and the steering council.

Enhancement of the language corresponds with the development of the CPython reference implementation. The mailing list python-dev is the primary forum for the language's development. Specific issues were originally discussed in the Roundup bug tracker hosted at by the foundation. In 2022, all issues and discussions were migrated to GitHub. Development originally took place on a self-hosted source-code repository running Mercurial, until Python moved to GitHub in January 2017.

CPython's public releases come in three types, distinguished by which part of the version number is incremented:

• Backward-incompatible versions, where code is expected to break and needs to be manually ported. The first part of the version number is incremented. These releases happen infrequently—version 3.0 was released 8 years after 2.0. According to Guido van Rossum, a version 4.0 is very unlikely to ever happen.
• Major or "feature" releases are largely compatible with the previous version but introduce new features. The second part of the version number is incremented. Starting with Python 3.9, these releases are expected to happen annually. Each major version is supported by bug fixes for several years after its release.
• Bugfix releases, which introduce no new features, occur about every 3 months and are made when a sufficient number of bugs have been fixed upstream since the last release. Security vulnerabilities are also patched in these releases. The third and final part of the version number is incremented.

Many alpha, beta, and release-candidates are also released as previews and for testing before final releases. Although there is a rough schedule for each release, they are often delayed if the code is not ready. Python's development team monitors the state of the code by running the large unit test suite during development.

The major academic conference on Python is PyCon. There are also special Python mentoring programs, such as PyLadies.

Python 3.12 removed wstr meaning Python extensions need to be modified, and 3.10 added pattern matching to the language.

Python 3.12 dropped some outdated modules, and more will be dropped in the future, deprecated as of 3.13; already deprecated array 'u' format code will emit DeprecationWarning since 3.13 and will be removed in Python 3.16. The 'w' format code should be used instead. Part of ctypes is also deprecated and http.server.CGIHTTPRequestHandler will emit a DeprecationWarning, and will be removed in 3.15. Using that code already has a high potential for both security and functionality bugs. Parts of the typing module are deprecated, e.g. creating a typing.NamedTuple class using keyword arguments to denote the fields and such (and more) will be disallowed in Python 3.15.

API documentation generators

Tools that can generate documentation for Python API include pydoc (available as part of the standard library), Sphinx, Pdoc and its forks, Doxygen and Graphviz, among others.

Naming

Название Python происходит от имени британской комедийной группы Monty Python , которой пользовался создатель Python Гвидо ван Россум при разработке языка. Ссылки на Монти Пайтон часто встречаются в коде и культуре Python; например, метасинтаксические переменные, часто используемые в литературе по Python, — это spam и egg вместо традиционных foo и bar . Официальная документация Python также содержит различные ссылки на подпрограммы Monty Python. Пользователей Python иногда называют «Pythonistas».

Префикс Py- используется, чтобы показать, что что-то связано с Python. Примеры использования этого префикса в именах приложений или библиотек Python включают к Python ( обычно Pygame — привязку SDL используемую для создания игр); PyQt и PyGTK , которые связывают Qt и GTK с Python соответственно; и PyPy — реализация Python, изначально написанная на Python.

Популярность

С 2003 года Python стабильно входит в десятку самых популярных языков программирования в индексе сообщества программистов TIOBE , где по состоянию на декабрь 2022 г. это был самый популярный язык (опередивший C, C++ и Java ). Он был выбран языком программирования года (за «самый высокий рост рейтингов за год») в 2007, 2010, 2018 и 2020 годах (единственный язык, который сделал это четыре раза по состоянию на 2020 год). ).

Крупные организации, использующие Python, включают Wikipedia , Google , Yahoo! , ЦЕРН , НАСА , Фейсбук , Амазон , Инстаграм , Спотифай , и некоторые более мелкие организации, такие как ILM и ИТА . Социальная новостная сеть Reddit была написана в основном на Python.

Использование

Основная статья: Список программного обеспечения Python

Работает на Python

Python может служить языком сценариев для веб-приложений , например, через mod_wsgi для веб-сервера Apache . С интерфейсом шлюза веб-сервера стандартный API был разработан для облегчения работы этих приложений. Веб-фреймворки, такие как Django , Pylons , Pyramid , TurboGears , web2py , Tornado , Flask , Bottle и Zope , помогают разработчикам проектировать и поддерживать сложные приложения. Pyjs и IronPython можно использовать для разработки клиентских приложений на основе Ajax. SQLAlchemy можно использовать в качестве преобразователя данных в реляционную базу данных. Twisted — это платформа для программирования связи между компьютерами, которая используется (например) Dropbox .

Такие библиотеки, как NumPy , SciPy и Matplotlib, позволяют эффективно использовать Python в научных вычислениях. со специализированными библиотеками, такими как Biopython и Astropy, обеспечивающими функциональность, специфичную для предметной области. SageMath — это система компьютерной алгебры с интерфейсом ноутбука , программируемым на Python: ее библиотека охватывает многие аспекты математики , включая алгебру , комбинаторику , числовую математику , теорию чисел и исчисление . OpenCV имеет привязки Python с богатым набором функций для компьютерного зрения и обработки изображений .

Python обычно используется в проектах искусственного интеллекта и проектах машинного обучения с помощью таких библиотек, как TensorFlow , Keras , Pytorch , scikit-learn и языка логики ProbLog . Python как язык сценариев с модульной архитектурой , простым синтаксисом и богатыми инструментами обработки текста часто используется для обработки естественного языка .

Комбинация Python и Пролога оказалась особенно полезной для приложений искусственного интеллекта, поскольку Пролог обеспечивает возможности представления знаний и рассуждения. Система Янус, в частности, использует сходство между этими двумя языками. отчасти из-за использования динамической типизации и простой рекурсивной природы их структуры данных. Типичные применения этой комбинации включают обработку естественного языка, визуальные запросы. ответы, геопространственные рассуждения и обработка семантических веб-данных. Система Natlog, реализованная на Python, использует грамматики определенных предложений (DCG) в качестве генераторов подсказок для генераторов преобразования текста в текст, таких как GPT3, и генераторов преобразования текста в изображение, таких как DALL-E или Stable Diffusion.

Python также можно использовать для графического пользовательского интерфейса (GUI) с помощью таких библиотек, как Tkinter .

Python был успешно встроен во многие программные продукты в качестве языка сценариев, в том числе в программное обеспечение для метода конечных элементов , такое как Abaqus , средства параметрического 3D-моделирования, такие как FreeCAD , пакеты 3D-анимации, такие как 3ds Max , Blender , Cinema 4D , Lightwave , Houdini , Maya , modo. , MotionBuilder , Softimage , наборщик визуальных эффектов Nuke , программы 2D-изображений, такие как GIMP , Inkscape , Scribus и Paint Shop Pro , и нотной записи, программы такие как партитура и капелла . GNU Debugger использует Python как красивый принтер для отображения сложных структур, таких как контейнеры C++. Esri пропагандирует Python как лучший выбор для написания скриптов в ArcGIS . Он также использовался в нескольких видеоиграх. и был принят в качестве первого из трех доступных языков программирования в Google App Engine , двумя другими являются Java и Go .

Многие операционные системы включают Python в качестве стандартного компонента. Он поставляется с большинством дистрибутивов Linux . AmigaOS 4 (с использованием Python 2.7), FreeBSD (в виде пакета), NetBSD и OpenBSD (в виде пакета) и может использоваться из командной строки (терминала). Многие дистрибутивы Linux используют установщики, написанные на Python: Ubuntu использует установщик Ubiquity , а Red Hat Linux и Fedora Linux используют установщик Anaconda . Gentoo Linux использует Python в своей системе управления пакетами Portage .

Python широко используется в индустрии информационной безопасности , в том числе при разработке эксплойтов.

Большая часть программного обеспечения Sugar для одного ноутбука на ребенка XO, разработанного в Sugar Labs по состоянию на 2008 год. , написан на Python. В проекте Raspberry Pi одноплатного компьютера Python был принят в качестве основного языка пользовательского программирования.

LibreOffice включает Python и намерен заменить Java на Python. Его поставщик сценариев Python является основной функцией. начиная с версии 4.0 от 7 февраля 2013 г.

Языки под влиянием Python

Дизайн и философия Python повлияли на многие другие языки программирования:

• Boo использует отступы, аналогичный синтаксис и аналогичную объектную модель.
• Cobra использует отступы и аналогичный синтаксис, а в ее документе «Благодарности» Python стоит на первом месте среди языков, оказавших на него влияние.
• CoffeeScript , язык программирования, который кросс-компилируется в JavaScript, имеет синтаксис, вдохновленный Python.
• ECMAScript — JavaScript заимствовал итераторы и генераторы из Python.
• GDScript — язык сценариев, очень похожий на Python, встроенный в игровой движок Godot .
• Go создан для «скорости работы на таком динамическом языке, как Python». и использует тот же синтаксис для нарезки массивов.
• Groovy руководствовался желанием перенести философию проектирования Python в Java .
• Джулия была разработана так, чтобы быть «такой же пригодной для общего программирования, как и Python».
• Mojo — нестрогий расширенный набор Python (например, все еще отсутствуют классы и добавлено, например, struct ).
• Ним использует отступы и аналогичный синтаксис.
• Юкихиро Создатель Ruby Мацумото сказал: «Мне нужен был язык сценариев, который был бы более мощным, чем Perl, и более объектно-ориентированным, чем Python. Вот почему я решил разработать свой собственный язык».
• Swift , язык программирования, разработанный Apple, имеет синтаксис, вдохновленный Python.
• Kotlin сочетает в себе функции Python и Java, минимизируя шаблонный код для повышения эффективности разработки.

Практика разработки Python также была эмулирована другими языками. Например, практика требования документа, описывающего обоснование и проблемы, связанные с изменением языка (в Python, PEP), также используется в Tcl . Эрланг , и Свифт.

См. также

• Синтаксис и семантика Python
• пип (менеджер пакетов)
• Список языков программирования
• История языков программирования
• Сравнение языков программирования

Ссылки

Источники

• «Python для искусственного интеллекта» . Питон Вики. 19 июля 2012 года. Архивировано из оригинала 1 ноября 2012 года . Проверено 3 декабря 2012 г.
• Пейн, Джоселин, изд. (август 2005 г.). «ИИ в Python» . Информационный бюллетень AI Expert . Амзи!. Архивировано из оригинала 26 марта 2012 года . Проверено 11 февраля 2012 г.
• «PyAIML 0.8.5: Индекс пакета Python» . Pypi.python.org . Проверено 17 июля 2013 г.
• Рассел, Стюарт Дж. и Норвиг, Питер (2009). Искусственный интеллект: современный подход (3-е изд.). Река Аппер-Сэдл, Нью-Джерси: Прентис-Холл. ISBN  978-0-13-604259-4 .

Дальнейшее чтение

• Дауни, Аллен Б. (май 2012 г.). Думай Python: как думать как ученый-компьютерщик (изд. версии 1.6.6). Издательство Кембриджского университета. ISBN  978-0-521-72596-5 .
• Гамильтон, Наоми (5 августа 2008 г.). «А-Я языков программирования: Python» . Компьютерный мир . Архивировано из оригинала 29 декабря 2008 года . Проверено 31 марта 2010 г.
• Лутц, Марк (2013). Изучение Python (5-е изд.). О'Рейли Медиа. ISBN  978-0-596-15806-4 .
• Саммерфилд, Марк (2009). Программирование на Python 3 (2-е изд.). Аддисон-Уэсли Профессионал. ISBN  978-0-321-68056-3 .
• Рамальо, Лучано (май 2022 г.). Свободный Питон . О'Рейли Медиа. ISBN  978-1-4920-5632-4 .

Внешние ссылки

• Официальный сайт