Python could be a wide used high-level artificial language for all-purpose programming, created by Guido van Rossum and initial free in 1991. Associate in Nursing taken language, Python features a style philosophy that emphasizes code readability (notably victimization whitespace indentation to delimit code blocks instead of crisp braces or keywords), and a syntax that permits programmers to specific ideas in fewer lines of code than doable in languages like C++ or Java. The language provides constructs meant to change writing clear programs on each alittle and enormous scale.
Python options a dynamic kind system and automatic memory management and supports multiple programming paradigms, as well as object-oriented, imperative, useful programming, and procedural designs. it's an oversized and comprehensive commonplace library.
Python interpreters area unit accessible for several operative systems, permitting Python code to run on a large kind of systems. CPython, the reference implementation of Python, is open supply software and features a community-based development model, as do nearly all of its variant implementations. CPython is managed by the non-profit Python computer code Foundation.
Python was planned within the late Nineteen Eighties,and its implementation began in Dec 1989 by Guido van Rossum at bone Wiskunde & Informatica (CWI) within the The Netherlands as a successor to the ABC language (itself galvanized by SETL) capable of exception handling and interfacing with the software system rhizopodan. Van Rossum is Python's principal author, and his continued central role decide the direction of Python is mirrored within the title given to him by the Python community, benevolent dictator for all times (BDFL).
About the origin of Python, Van Rossum wrote in 1996:
Over six years past, in Dec 1989, i used to be longing for a "hobby" programming project that will keep Pine Tree State occupied throughout the week around Christmas. My office ... would be closed, however I had a data processor, and not a lot of else on my hands. i made a decision to write down AN interpreter for the new scripting language I had been puzzling over lately: a descendant of ABC that will charm to Unix/C hackers. I selected Python as a operating title for the project, being in an exceedingly slightly irreverent mood (and a giant fan of Monty Python's Flying Circus).
Python 2.0 was free on sixteen Gregorian calendar month 2000 and had several major new options, together with a cycle-detecting dustman and support for Unicode. With this unleash the event method was modified and have become a lot of clear and community-backed.
Python 3.0 (which early in its development was unremarkably cited as Python 3000 or py3k), a major, backwards-incompatible unleash, was free on three Dec 2008 when a protracted amount of testing. several of its major options are backported to the backwards-compatible Python a pair of.6.x[33] and a pair of.7.x version series.
The End Of Life date (EOL, sunset date) for Python a pair of.7 was ab initio set at 2015, then delayed to 2020 out of concern that an outsized body of existing code cannot simply be forward-ported to Python three. In Gregorian calendar month 2017, Google declared work on a Python a pair of.7 to travel transcompiler, that The Register speculated was in response to Python a pair of.7's planned end-of-life however Google cited performance below coinciding workloads as their solely motivation.
Python may be a multi-paradigm programming language: object-oriented programming and structured programming ar absolutely supported, and lots of language options support purposeful programming and aspect-oriented programming (including by metaprogramming and metaobjects (magic methods)). several alternative paradigms are supported via extensions, as well as style by contract and logic programming.
Python uses dynamic writing and a mixture of reference tally and a cycle-detecting employee for memory management. a vital feature of Python is dynamic name resolution (late binding), that binds technique and variable names throughout program execution.
The design of Python offers some support for purposeful programming within the Lisp tradition. The language has map(), reduce() and filter() functions; list comprehensions, dictionaries, and sets; and generator expressions. the quality library has 2 modules (itertools and functools) that implement purposeful tools borrowed from Haskell and commonplace cubic centimetre.
The core philosophy of the language is summarized by the document The Zen of Python (PEP 20), which has aphorisms such as:
Beautiful is best than ugly
Explicit is best than implicit
Simple is best than advanced
Complex is best than difficult
Readability counts
Rather than requiring all desired practicality to be engineered into the language's core, Python was designed to be extremely protrusible. Python may also be embedded in existing applications that require a programmable interface. This style of atiny low core language with an oversized commonplace library ANd an simply protrusible interpreter was meant by Van Rossum from the beginning due to his frustrations with first principle, that espoused the other mental attitude.
While giving alternative in committal to writing methodology, the Python philosophy rejects exuberant syntax, like in Perl, in favor of a sparser, less-cluttered synchronic linguistics. As Alex Martelli place it: "To describe one thing as clever isn't thought-about a compliment within the Python culture."Python's philosophy rejects the Perl "there is over a way to try and do it" approach to language style in favor of "there ought to be one—and ideally solely one—obvious thanks to do it".
Python's developers attempt to avoid premature improvement, and furthermore, reject patches to non-critical components of CPython that might provide a marginal increase in speed at the price of clarity. once speed is very important, a Python computer programmer will move time-critical functions to extension modules written in languages like C, or strive victimisation PyPy, a just-in-time compiler. Cython is additionally accessible, that interprets a Python script into C and makes direct C-level API calls into the Python interpreter.
An important goal of Python's developers is creating it fun to use. this is often mirrored within the origin of the name, that comes from Monty Python, ANd in an sometimes teasing approach to tutorials and reference materials, like victimisation examples that seek advice from spam and eggs rather than the quality foo and bar.
A common neologism within the Python community is pythonic, which may have a large vary of meanings associated with program vogue. to mention that code is pythonic is to mention that it uses Python idioms well, that it's natural or shows fluency within the language, that it conforms with Python's minimalist philosophy and stress on readability. In distinction, code that's troublesome to grasp or reads sort of a rough transcription from another artificial language is termed unpythonic.
Users and admirers of Python, particularly those thought-about knowledgeable or full-fledged, ar typically cited as Pythonists, Pythonistas, and Pythoneers.
Syntax and semantics
Python is meant to be a extremely legible language. it's designed to possess associate unlittered visual layout, typically victimization English keywords wherever alternative languages use punctuation. Further, Python has fewer grammar exceptions and special cases than C or Pascal.
Indentation
Python uses whitespace indentation to delimit blocks – instead of permed braces or keywords. a rise in indentation comes once bound statements; a decrease in indentation signifies the tip of the present block. This feature is additionally typically termed the off-side rule.
Statements and control flow
Python's statements embrace (among others):
The assignment statement (token '=', the equals sign). This operates otherwise than in ancient imperative programming languages, and this elementary mechanism (including the character of Python's version of variables) illuminates several alternative options of the language. Assignment in C, e.g., x = 2, interprets to "typed variable name x receives a duplicate of numeric worth 2". The (right-hand) worth is traced into AN allotted storage location that the (left-hand) variable name is that the symbolic address. The memory allotted to the variable is giant enough (potentially quite large) for the declared sort. within the simplest case of Python assignment, mistreatment constant example, x = 2, interprets to "(generic) name x receives a respect to a separate, dynamically allotted object of numeric (int) style of worth two." this is often termed binding the name to the article. Since the name's storage location does not contain the indicated worth, it's improper to decision it a variable. Names could also be afterwards rebound at any time to things of greatly varied varieties, together with strings, procedures, complicated objects with knowledge and strategies, etc. sequent assignments of a standard worth to multiple names, e.g., x = two; y = 2; z = 2 end in allocating storage to (at most) 3 names and one numeric object, to that all 3 names are sure. Since a reputation could be a generic reference holder it's unreasonable to associate a hard and fast knowledge sort with it. but at a given time a reputation are guaranteed to some object, which is able to have a type; therefore there's dynamic typewriting.
The if statement, that not absolutely executes a block of code, beside else and elif (a contraction of else-if).
The for statement, that iterates over AN iterable object, capturing every component to an area variable to be used by the connected block.
The whereas statement, that executes a block of code as long as its condition is true.
The strive statement, that permits exceptions raised in its connected code block to be caught and handled by except clauses; it conjointly ensures that clean-up code in an exceedingly finally block can continually be run in spite of however the block exits.
The class statement, that executes a block of code and attaches its native namespace to a category, to be used in object-oriented programming.
The def statement, that defines a operate or technique.
The with statement (from Python two.5), that encloses a code block among a context manager (for example, effort a lock before the block of code is run and emotional the lock afterward, or gap a file so closing it), permitting Resource Acquisition Is format (RAII)-like behavior.
The pass statement, that is a NOP. it's syntactically required to form AN empty code block.
The assert statement, used throughout debugging to see for conditions that need to apply.
The yield statement, that returns a price from a generator operate. From Python two.5, yield is additionally AN operator. this type is employed to implement coroutines.
The import statement, that is employed to import modules whose functions or variables will be utilized in this program.
The print statement was modified to the print() operate in Python three.
Python doesn't support tail decision improvement or fantabulous continuations, and, per Guido van Rossum, it ne'er can. but, higher support for coroutine-like practicality is provided in two.5, by extending Python's generators. Before two.5, generators were lazy iterators; data was passed unidirectionally out of the generator. As of Python two.5, it's attainable to pass data back to a generator operate, and as of Python three.3, the data will be knowledgeable multiple stack levels.
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