mode is an optional string that specifies the mode in which the file isopened. It defaults to 'r' which means open for reading in text mode.Other common values are 'w' for writing (truncating the file if italready exists), 'x' for exclusive creation, and 'a' for appending(which on some Unix systems, means that all writes append to the end ofthe file regardless of the current seek position). In text mode, ifencoding is not specified the encoding used is platform-dependent:locale.getencoding() is called to get the current locale encoding.(For reading and writing raw bytes use binary mode and leaveencoding unspecified.) The available modes are:
As mentioned in the Overview, Python distinguishes between binaryand text I/O. Files opened in binary mode (including 'b' in the modeargument) return contents as bytes objects without any decoding. Intext mode (the default, or when 't' is included in the mode argument),the contents of the file are returned as str, the bytes having beenfirst decoded using a platform-dependent encoding or using the specifiedencoding if given.
buffering is an optional integer used to set the buffering policy. Pass 0to switch buffering off (only allowed in binary mode), 1 to select linebuffering (only usable when writing in text mode), and an integer > 1 to indicate the sizein bytes of a fixed-size chunk buffer. Note that specifying a buffer size thisway applies for binary buffered I/O, but TextIOWrapper (i.e., files openedwith mode='r+') would have another buffering. To disable buffering inTextIOWrapper, consider using the write_through flag forio.TextIOWrapper.reconfigure(). When no buffering argument isgiven, the default buffering policy works as follows:
If closefd is False and a file descriptor rather than a filename wasgiven, the underlying file descriptor will be kept open when the file isclosed. If a filename is given closefd must be True (the default);otherwise, an error will be raised.
A custom opener can be used by passing a callable as opener. The underlyingfile descriptor for the file object is then obtained by calling opener with(file, flags). opener must return an open file descriptor (passingos.open as opener results in functionality similar to passingNone).
The type of file object returned by the open() functiondepends on the mode. When open() is used to open a file in a textmode ('w', 'r', 'wt', 'rt', etc.), it returns a subclass ofio.TextIOBase (specifically io.TextIOWrapper). When usedto open a file in a binary mode with buffering, the returned class is asubclass of io.BufferedIOBase. The exact class varies: in readbinary mode, it returns an io.BufferedReader; in write binary andappend binary modes, it returns an io.BufferedWriter, and inread/write mode, it returns an io.BufferedRandom. When buffering isdisabled, the raw stream, a subclass of io.RawIOBase,io.FileIO, is returned.
Open source is source code that is made freely available for possible modification and redistribution. Products include permission to use the source code,[1] design documents,[2] or content of the product. The open-source model is a decentralized software development model that encourages open collaboration.[3][4]A main principle of open-source software development is peer production, with products such as source code, blueprints, and documentation freely available to the public. The open-source movement in software began as a response to the limitations of proprietary code. The model is used for projects such as in open-source appropriate technology,[5] and open-source drug discovery.[6][7]
Open source promotes universal access via an open-source or free license to a product's design or blueprint, and universal redistribution of that design or blueprint.[8][9] Before the phrase open source became widely adopted, developers and producers used a variety of other terms. Open source gained hold with the rise of the Internet.[10] The open-source software movement arose to clarify copyright, licensing, domain, and consumer issues.
Generally, open source refers to a computer program in which the source code is available to the general public for use or modification from its original design. Code is released under the terms of a software license. Depending on the license terms, others may then download, modify, and publish their version (fork) back to the community. Many large formal institutions have sprung up to support the development of the open-source movement, including the Apache Software Foundation, which supports community projects such as the open-source framework Apache Hadoop and the open-source HTTP server Apache HTTP.
In 1911, independent automaker Henry Ford won a challenge to the Selden patent. The result was that the Selden patent became virtually worthless and a new association (which would eventually become the Motor Vehicle Manufacturers Association) was formed.[11] The new association instituted a cross-licensing agreement among all US automotive manufacturers: although each company would develop technology and file patents, these patents were shared openly and without the exchange of money among all the manufacturers.[11] By the time the US entered World War II, 92 Ford patents and 515 patents from other companies were being shared among these manufacturers, without any exchange of money (or lawsuits).[11]
Early instances of the free sharing of source code include IBM's source releases of its operating systems and other programs in the 1950s and 1960s, and the SHARE user group that formed to facilitate the exchange of software.[12][13] Beginning in the 1960s, ARPANET researchers used an open "Request for Comments" (RFC) process to encourage feedback in early telecommunication network protocols. This led to the birth of the early Internet in 1969.
Open source as a term emerged in the late 1990s by a group of people in the free software movement who were critical of the political agenda and moral philosophy implied in the term "free software" and sought to reframe the discourse to reflect a more commercially minded position.[14] In addition, the ambiguity of the term "free software" was seen as discouraging business adoption.[15][16] However, the ambiguity of the word "free" exists primarily in English as it can refer to cost. The group included Christine Peterson, Todd Anderson, Larry Augustin, Jon Hall, Sam Ockman, Michael Tiemann and Eric S. Raymond. Peterson suggested "open source" at a meeting[17] held at Palo Alto, California, in reaction to Netscape's announcement in January 1998 of a source code release for Navigator. Linus Torvalds gave his support the following day, and Phil Hughes backed the term in Linux Journal. Richard Stallman, the founder of the free software movement, quickly decided against endorsing the term.[17][18] Netscape released its source code under the Netscape Public License and later under the Mozilla Public License.[19]
The term gained further visibility through an event organized in April 1998 by technology publisher Tim O'Reilly. Originally titled the "Freeware Summit" and later known as the "Open Source Summit",[21] the event was attended by the leaders of many of the most important free and open-source projects, including Linus Torvalds, Larry Wall, Brian Behlendorf, Eric Allman, Guido van Rossum, Michael Tiemann, Paul Vixie, Jamie Zawinski, and Eric Raymond. At that meeting, alternatives to the term "free software" were discussed. Tiemann argued for "sourceware" as a new term, while Raymond argued for "open source." The assembled developers took a vote, and the winner was announced at a press conference the same evening.[21]
Being organized as effectively a "consumers' cooperative", open source eliminates some of the access costs of consumers and creators of derivative works by reducing the restrictions of copyright. Basic economic theory predicts that lower costs would lead to higher consumption and also more frequent creation of derivative works. Organizations such as Creative Commons host websites where individuals can file for alternative "licenses", or levels of restriction, for their works.[24]These self-made protections free the general society of the costs of policing copyright infringement.
Others argue that since consumers do not pay for their copies, creators are unable to recoup the initial cost of production and thus have little economic incentive to create in the first place. By this argument, consumers would lose out because some of the goods they would otherwise purchase would not be available. In practice, content producers can choose whether to adopt a proprietary license and charge for copies, or an open license. Some goods which require large amounts of professional research and development, such as the pharmaceutical industry (which depends largely on patents, not copyright for intellectual property protection) are almost exclusively proprietary, although increasingly sophisticated technologies are being developed on open-source principles.[25]
There is evidence that open-source development creates enormous value.[26] For example, in the context of open-source hardware design, digital designs are shared for free and anyone with access to digital manufacturing technologies (e.g. RepRap 3D printers) can replicate the product for the cost of materials.[27] The original sharer may receive feedback and potentially improvements on the original design from the peer production community.
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