99-627: Objective-C is a high-level general-purpose , object-oriented programming language that adds Smalltalk -style message passing (messaging) to the C programming language. Originally developed by Brad Cox and Tom Love in the early 1980s, it was selected by NeXT for its NeXTSTEP operating system . Due to Apple macOS ’s direct lineage from NeXTSTEP, Objective-C was the standard language used, supported, and promoted by Apple for developing macOS and iOS applications (via their respective application programming interfaces ( APIs ), Cocoa and Cocoa Touch ) from 1997, when Apple purchased NeXT until
198-403: A release message to self, and return nil to indicate that initialization failed. Any checking for such errors must only be performed after having called the superclass initialization to ensure that destroying the object will be done correctly. If a class has more than one initialization method, only one of them (the designated initializer ) needs to follow this pattern; others should call
297-706: A Balkanisation of the "Open Source Universe". Linus Torvalds, who decided not to adopt the GPLv3 for the Linux kernel, reiterated his criticism several years later. GPLv3 improved compatibility with several free software licenses such as the Apache License, version 2.0, and the GNU Affero General Public License, which GPLv2 could not be combined with. However, GPLv3 software could only be combined and share code with GPLv2 software if
396-622: A patent infringement claim or other litigation to impair users' freedom under the license. By 1990, it was becoming apparent that a less restrictive license would be strategically useful for the C library and for software libraries that essentially did the job of existing proprietary ones; when version 2 of the GPL (GPLv2) was released in June 1991, therefore, a second license – the GNU Library General Public License –
495-452: A "user" and a "consumer product". It also explicitly removed the section on "Geographical Limitations", the probable removal of this section having been announced at the launch of the public consultation. The fourth discussion draft, which was the last, was released on 31 May 2007. It introduced Apache License version 2.0 compatibility (prior versions are incompatible), clarified the role of outside contractors, and made an exception to avoid
594-408: A US federal court ruled that an open-source license is an enforceable contract. In October 2021 SFC sued Vizio over breach of contract as an end user to request source code for Vizio's TVs, a federal judge has ruled in the interim that the GPL is an enforceable contract by end users as well as a license for copyright holders. The text of the GPL is itself copyrighted , and the copyright is held by
693-523: A corresponding implementation unless they are abstract . The Smalltalk-style programming as used in Objective-C allows messages to go unimplemented, with the method resolved to its implementation at runtime. For example, a message may be sent to a collection of objects, to which only some will be expected to respond, without fear of producing runtime errors. Message passing also does not require that an object be defined at compile time . An implementation
792-421: A few practical changes to existing tools. Specifically, they needed to support objects in a flexible manner, come supplied with a usable set of libraries , and allow for the code (and any resources needed by the code) to be bundled into one cross-platform format. Love and Cox eventually formed PPI to commercialize their product, which coupled an Objective-C compiler with class libraries. In 1986, Cox published
891-428: A focus on usability over optimal program efficiency. Unlike low-level assembly languages , high-level languages have few, if any, language elements that translate directly into a machine's native opcodes . Other features, such as string handling routines, object-oriented language features, and file input/output, may also be present. One thing to note about high-level programming languages is that these languages allow
990-453: A fully general lambda abstraction in a programming language for the first time. "High-level language" refers to the higher level of abstraction from machine language . Rather than dealing with registers, memory addresses, and call stacks, high-level languages deal with variables, arrays, objects , complex arithmetic or Boolean expressions , subroutines and functions, loops, threads , locks, and other abstract computer science concepts, with
1089-443: A licensee has no right to redistribute it, not even in modified form (barring fair use ), except under the terms of the license. One is only required to adhere to the terms of the GPL if one wishes to exercise rights normally restricted by copyright law, such as redistribution. Conversely, if one distributes copies of the work without abiding by the terms of the GPL (for instance, by keeping the source code secret), they can be sued by
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#17327651195391188-479: A method ; one sends a message . This is unlike the Simula -style programming model used by C++ . The difference between these two concepts is in how the code referenced by the method or message name is executed. In a Simula-style language, the method name is in most cases bound to a section of code in the target class by the compiler. In Smalltalk and Objective-C, the target of a message is resolved at runtime, with
1287-460: A modified derivative of a GPL licensed content management system is not required to distribute its changes to the underlying software, because the modified web portal is not being redistributed but rather hosted, and also because the web portal output is also not a derivative work of the GPL licensed content management system. There has been debate on whether it is a violation of the GPLv1 to release
1386-411: A name labeling the argument that is part of the method name, followed by a colon followed by the expected argument type in parentheses and the argument name. The label can be omitted. A derivative of the interface definition is the category , which allows one to add methods to existing classes. The interface only declares the class interface and not the methods themselves: the actual code is written in
1485-491: A platform for custom programming. To circumvent the terms of the GPL , NeXT had originally intended to ship the Objective-C frontend separately, allowing the user to link it with GCC to produce the compiler executable. Though initially accepted by Richard M. Stallman , this plan was rejected after Stallman consulted with GNU's lawyers and NeXT agreed to make Objective-C part of GCC. The work to extend GNU Compiler Collection (GCC)
1584-536: A series of widely used free software licenses , or copyleft licenses, that guarantee end users the freedoms to run, study, share, and modify the software. The GPL was the first copyleft license for general use. It was originally written by Richard Stallman , the founder of the Free Software Foundation (FSF), for the GNU Project . The license grants the recipients of a computer program
1683-623: A specific system architecture . Abstraction penalty is the cost that high-level programming techniques pay for being unable to optimize performance or use certain hardware because they don't take advantage of certain low-level architectural resources. High-level programming exhibits features like more generic data structures and operations, run-time interpretation, and intermediate code files; which often result in execution of far more operations than necessary, higher memory consumption, and larger binary program size. For this reason, code which needs to run particularly quickly and efficiently may require
1782-506: Is a list of methods that a class can opt to implement. It is specified in the documentation, since it has no presence in the language. Informal protocols are implemented as a category (see below) on NSObject and often include optional methods, which, if implemented, can change the behavior of a class. For example, a text field class might have a delegate that implements an informal protocol with an optional method for performing auto-completion of user-typed text. The text field discovers whether
1881-418: Is allowed to charge a fee for this service or do this free of charge. This latter point distinguishes the GPL from software licenses that prohibit commercial redistribution. The FSF argues that free software should not place restrictions on commercial use, and the GPL explicitly states that GPL works may be sold at any price. The GPL additionally states that a distributor may not impose "further restrictions on
1980-449: Is applied to ensure that end users retain the freedoms defined above. However, software running as an application program under a GPL-licensed operating system such as Linux is not required to be licensed under GPL or to be distributed with source-code availability—the licensing depends only on the used libraries and software components and not on the underlying platform. For example, if a program consists only of original source code , or
2079-529: Is based on OpenStep interface objects and is the most significant Objective-C environment being used for active development. At WWDC 2014, Apple introduced a new language, Swift , which was characterized as "Objective-C without the C". Objective-C is a thin layer atop C and is a "strict superset " of C, meaning that it is possible to compile any C program with an Objective-C compiler and to freely include C language code within an Objective-C class. Objective-C derives its object syntax from Smalltalk . All of
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#17327651195392178-427: Is combined with source code from other software components , then the custom software components need not be licensed under GPL and need not make their source code available; even if the underlying operating system used is licensed under the GPL, applications running on it are not considered derivative works. Only if GPL licensed parts are used in a program (and the program is distributed), then all other source code of
2277-501: Is how the compiled code was available and there are "clear directions" on where to find the source code. The FSF does not hold the copyright for a work released under the GPL unless an author explicitly assigns copyrights to the FSF (which seldom happens except for programs that are part of the GNU project). Only the individual copyright holders have the authority to sue when a license violation
2376-498: Is inherently at a slightly higher level than the microcode or micro-operations used internally in many processors. There are three general modes of execution for modern high-level languages: Note that languages are not strictly interpreted languages or compiled languages. Rather, implementations of language behavior use interpreting or compiling. For example, ALGOL 60 and Fortran have both been interpreted (even though they were more typically compiled). Similarly, Java shows
2475-488: Is named objc_msg_sendv , but it has been deprecated in favor of a modern lookup system under objc_msg_lookup . Both styles of programming have multiple strengths and weaknesses. Object-oriented programming in the Simula ( C++ ) style allows multiple inheritance and faster execution by using compile-time binding whenever possible, but it does not support dynamic binding by default. It also forces all methods to have
2574-418: Is never an allocated object that hasn't undergone initialization (and because it is unwise to keep the intermediate result since -init can return a different object than that on which it is called). Instantiation with the default, no-parameter initializer: Instantiation with a custom initializer: In the case where no custom initialization is being performed, the "new" method can often be used in place of
2673-488: Is not necessarily known at link time which method will be called because the class of the receiver (the object being sent the message) need not be known until runtime. Once an Objective-C class is written, it can be instantiated. This is done by first allocating an uninitialized instance of the class (an object) and then by initializing it. An object is not fully functional until both steps have been completed. These steps should be accomplished with one line of code so that there
2772-500: Is possible for a high-level language to be directly implemented by a computer – the computer directly executes the HLL code. This is known as a high-level language computer architecture – the computer architecture itself is designed to be targeted by a specific high-level language. The Burroughs large systems were target machines for ALGOL 60 , for example. GPL The GNU General Public Licenses ( GNU GPL or simply GPL ) are
2871-500: Is prohibited by copyright law . The FSF argues that freedom-respecting free software should also not restrict commercial use and distribution (including redistribution): In purely private (or internal) use—with no sales and no distribution—the software code may be modified and parts reused without requiring the source code to be released. For sales or distribution, the entire source code needs to be made available to end users, including any code changes and additions—in that case, copyleft
2970-449: Is still required for the method to be called in the derived object. (See the dynamic typing section below for more advantages of dynamic (late) binding.) Objective-C requires that the interface and implementation of a class be in separately declared code blocks. By convention, developers place the interface in a header file and the implementation in a code file. The header files, normally suffixed .h, are similar to C header files while
3069-499: Is suspected. Software under the GPL may be run for all purposes, including commercial purposes and even as a tool for creating proprietary software , such as when using GPL-licensed compilers . Users or companies who distribute GPL-licensed works (e.g. software), may charge a fee for copies or give them free of charge. This distinguishes the GPL from shareware software licenses that allow copying for personal use but prohibit commercial distribution or proprietary licenses where copying
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3168-424: Is to refer to an instance method, with the class and then method names appended and colons changed to underscores. As the order of parameters is part of the method name, it cannot be changed to suit coding style or expression as with true named parameters. However, internal names of the function are rarely used directly. Generally, messages are converted to function calls defined in the Objective-C runtime library. It
3267-698: The ASP loophole in the GPL . As there were concerns expressed about the administrative costs of checking code for this additional requirement, it was decided to keep the GPL and the AGPL license separated. Others, notably some high-profile Linux kernel developers such as Linus Torvalds , Greg Kroah-Hartman , and Andrew Morton , commented to the mass media and made public statements about their objections to parts of discussion drafts 1 and 2. The kernel developers referred to GPLv3 draft clauses regarding DRM / Tivoization , patents, and "additional restrictions", and warned of
3366-508: The AGPL (v1) , and patent deals between Microsoft and distributors of free and open-source software, which some viewed as an attempt to use patents as a weapon against the free software community. Version 3 was developed as an attempt to address these concerns and was officially released on 29 June 2007. Version 1 of the GNU GPL, released on 25 February 1989, was written to protect against
3465-520: The C language , and similar languages, were most often considered "high-level", as it supported concepts such as expression evaluation, parameterised recursive functions, and data types and structures, while assembly language was considered "low-level". Today, many programmers might refer to C as low-level, as it lacks a large runtime-system (no garbage collection, etc.), basically supports only scalar operations, and provides direct memory addressing; it therefore, readily blends with assembly language and
3564-492: The Software Freedom Law Center . According to Stallman, the most important changes were in relation to software patents , free software license compatibility, the definition of "source code", and hardware restrictions on software modifications, such as tivoization . Other changes related to internationalization, how license violations are handled, and how additional permissions could be granted by
3663-555: The WIPO Copyright Treaty , and that those who convey the work waive all legal power to prohibit circumvention of the technical protection measure "to the extent such circumvention is effected by exercising rights under this License with respect to the covered work". This means that users cannot be held liable for circumventing DRM implemented using GPLv3-licensed code under laws such as the U.S. Digital Millennium Copyright Act (DMCA). The distribution rights granted by
3762-540: The receiver — is not guaranteed to respond to a message, and if it does not, it raises an exception. Sending the message method to the object pointed to by the pointer obj would require the following code in C++ : In Objective-C, this is written as follows: The "method" call is translated by the compiler to the objc_msgSend(id self, SEL op, ...) family of runtime functions. Different implementations handle modern additions like super . In GNU families this function
3861-420: The system architecture which they were written for without major revision. This is the engineering 'trade-off' for the 'Abstraction Penalty'. Examples of high-level programming languages in active use today include Python , JavaScript , Visual Basic , Delphi , Perl , PHP , ECMAScript , Ruby , C# , Java and many others. The terms high-level and low-level are inherently relative. Some decades ago,
3960-657: The Free Software Foundation. The FSF permits people to create new licenses based on the GPL, as long as the derived licenses do not use the GPL preamble without permission. This is discouraged, however, since such a license might be incompatible with the GPL and causes a perceived license proliferation . Other licenses created by the GNU project include the GNU Lesser General Public License , GNU Free Documentation License , and GNU Affero General Public License . The text of
4059-404: The GPL for modified versions of the work are not unconditional. When someone distributes a GPL licensed work plus their own modifications, the requirements for distributing the whole work cannot be any greater than the requirements that are in the GPL. This requirement is known as copyleft. It earns its legal power from the use of copyright on software programs. Because a GPL work is copyrighted,
Objective-C - Misplaced Pages Continue
4158-527: The GPL is not itself under the GPL. The license's copyright disallows modification of the license. Copying and distributing the license is allowed since the GPL requires recipients to get "a copy of this License along with the Program". According to the GPL FAQ, anyone can make a new license using a modified version of the GPL as long as they use a different name for the license, do not mention "GNU", and remove
4257-539: The GPL license family has been one of the most popular software licenses in the free and open-source software (FOSS) domain. Prominent free software programs licensed under the GPL include the Linux kernel and the GNU Compiler Collection (GCC). David A. Wheeler argues that the copyleft provided by the GPL was crucial to the success of Linux -based systems, giving the programmers who contributed to
4356-588: The GPL license includes an optional "any later version" clause, allowing users to choose between the original terms or the terms in new versions as updated by the FSF. Software projects licensed with the optional "or later" clause include the GNU Project, while projects like the Linux kernel is licensed under GPLv2 only. The "or any later version" clause is sometimes known as a "lifeboat clause" since it allows combinations between different versions of GPL-licensed software to maintain compatibility. The original GPL
4455-431: The GPL licensed program, they may still use the software within their organization however they like, and works (including programs) constructed by the use of the program are not required to be covered by this license. Software developer Allison Randal argued that the GPLv3 as a license is unnecessarily confusing for lay readers, and could be simplified while retaining the same conditions and legal force. In April 2017,
4554-464: The GPLv2 license used had the optional "or later" clause and the software was upgraded to GPLv3. While the "GPLv2 or any later version" clause is considered by FSF as the most common form of licensing GPLv2 software, Toybox developer Rob Landley described it as a lifeboat clause . Software projects licensed with the optional "or later" clause include the GNU Project , while a prominent example without
4653-875: The Objective-C frontend to Clang . The GNU project started work on its free software implementation of Cocoa , named GNUstep , based on the OpenStep standard. Dennis Glatting wrote the first GNU Objective-C runtime in 1992. The current GNU Objective-C runtime, in use since 1993, is the one developed by Kresten Krab Thorup while he was a university student in Denmark . Thorup also worked at NeXT from 1993 to 1996. After acquiring NeXT in 1996, Apple Computer used OpenStep in its then-new operating system, Mac OS X . This included Objective-C, NeXT's Objective-C-based developer tool, Project Builder , and its interface design tool, Interface Builder . Both were later merged into one application, Xcode . Most of Apple's current Cocoa API
4752-675: The Objective-C trademark) and extended the GCC compiler to support Objective-C. NeXT developed the Application Kit (AppKit) and Foundation Kit libraries on which the NeXTSTEP user interface and Interface Builder were based. While the NeXT workstations failed to make a great impact in the marketplace, the tools were widely lauded in the industry. NeXT dropped hardware production and focused on software tools, selling NeXTSTEP (and OPENSTEP) as
4851-540: The Software Package Data Exchange (SPDX). The license includes instructions to specify "version 2 of the License, or (at your option) any later version" to allow the flexible optional use of either version 2 or 3, but some developers change this to specify "version 2" only. In late 2005, the Free Software Foundation (FSF) announced work on version 3 of the GPL (GPLv3). On 16 January 2006,
4950-490: The abilities of Smalltalk . He soon had a working implementation of an object-oriented extension to the C language, which he named Object-Oriented Pre-Compiler (OOPC). Love was hired by Schlumberger Research in 1982 and had the opportunity to acquire the first commercial copy of Smalltalk-80, which further influenced the development of their brainchild. To demonstrate that real progress could be made, Cox showed that making interchangeable software components really needed only
5049-428: The alloc-init messages: Also, some classes implement class method initializers. Like +new , they combine +alloc and -init , but unlike +new , they return an autoreleased instance. Some class method initializers take parameters: The alloc message allocates enough memory to hold all the instance variables for an object, sets all the instance variables to zero values, and turns the memory into an instance of
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#17327651195395148-466: The class; at no point during the initialization is the memory an instance of the superclass. The init message performs the set-up of the instance upon creation. The init method is often written as follows: In the above example, notice the id return type. This type stands for pointer to any object in Objective-C (See the Dynamic typing section). The initializer pattern is used to assure that
5247-429: The clause is the Linux kernel. The final version of the license text was published on 29 June 2007. The terms and conditions of the GPL must be made available to anybody receiving a copy of a work that has a GPL applied to it ("the licensee"). Any licensee who adheres to the terms and conditions is given permission to modify the work, as well as to copy and redistribute the work or any derivative version. The licensee
5346-470: The copyright holder. The concept of "software propagation", as a term for the copying and duplication of software, was explicitly defined. The public consultation process was coordinated by the Free Software Foundation with assistance from Software Freedom Law Center, Free Software Foundation Europe , and other free software groups. Comments were collected from the public via the gplv3.fsf.org web portal, using purpose-written software called stet . During
5445-574: The delegate implements that method (via reflective programming (reflection)) and, if so, calls the delegate's method to support the auto-complete feature. High-level programming language In computer science , a high-level programming language is a programming language with strong abstraction from the details of the computer . In contrast to low-level programming languages , it may use natural language elements , be easier to use, or may automate (or even hide entirely) significant areas of computing systems (e.g. memory management ), making
5544-639: The designated initializer instead of the superclass initializer. In other programming languages, these are called interfaces . Objective-C was extended at NeXT to introduce the concept of multiple inheritance of specification, but not implementation, through the introduction of protocols . This is a pattern achievable either as an abstract multiple inherited base class in C++ , or as an interface (as in Java and C# ). Objective-C makes use of ad hoc protocols called informal protocols and compiler-enforced protocols called formal protocols . An informal protocol
5643-473: The difficulty of trying to apply these labels to languages, rather than to implementations; Java is compiled to bytecode which is then executed by either interpreting (in a Java virtual machine (JVM)) or compiling (typically with a just-in-time compiler such as HotSpot , again in a JVM). Moreover, compiling, transcompiling, and interpreting is not strictly limited to only a description of the compiler artifact (binary executable or IL assembly). Alternatively, it
5742-399: The first "discussion draft" of GPLv3 was published, and the public consultation began. The public consultation was originally planned for nine to fifteen months, but ultimately lasted eighteen months, with four drafts being published. The official GPLv3 was released by the FSF on 29 June 2007. GPLv3 was written by Richard Stallman, with legal counsel from Eben Moglen and Richard Fontana from
5841-448: The form: In the above, plus signs denote class methods , or methods that can be called on the class itself (not on an instance), and minus signs denote instance methods , which can only be called on a particular instance of the class. Class methods also have no access to instance variables . The code above is roughly equivalent to the following C++ interface: Note that instanceMethod2With2Parameters:param2_callName: demonstrates
5940-431: The goal of aggregating the most popular constructs with new or improved features. An example of this is Scala which maintains backward compatibility with Java , meaning that programs and libraries written in Java will continue to be usable even if a programming shop switches to Scala; this makes the transition easier and the lifespan of such high-level coding indefinite. In contrast, low-level programs rarely survive beyond
6039-611: The higher abstraction may allow for more powerful techniques providing better overall results than their low-level counterparts in particular settings. High-level languages are designed independent of a specific computing system architecture . This facilitates executing a program written in such a language on any computing system with compatible support for the Interpreted or JIT program. High-level languages can be improved as their designers develop improvements. In other cases, new high-level languages evolve from one or more others with
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#17327651195396138-443: The implementation (method) files, normally suffixed .m, can be very similar to C code files. This is analogous to class declarations as used in other object-oriented languages, such as C++ or Python. The interface of a class is usually defined in a header file. A common convention is to name the header file after the name of the class, e.g. Ball.h would contain the interface for the class Ball . An interface declaration takes
6237-532: The implementation file. Implementation (method) files normally have the file extension .m , which originally signified "messages". Methods are written using their interface declarations. Comparing Objective-C and C: The syntax allows pseudo- naming of arguments . Internal representations of a method vary between different implementations of Objective-C. If myColor is of the class Color , instance method -changeColorToRed:green:blue: might be internally labeled _i_Color_changeColorToRed_green_blue . The i
6336-499: The interleaving of selector segments with argument expressions, for which there is no direct equivalent in C/C++. Return types can be any standard C type, a pointer to a generic Objective-C object, a pointer to a specific type of object such as NSArray *, NSImage *, or NSString *, or a pointer to the class to which the method belongs (instancetype). The default return type is the generic Objective-C type id . Method arguments begin with
6435-492: The introduction of the Swift language in 2014. Objective-C programs developed for non-Apple operating systems or that are not dependent on Apple's APIs may also be compiled for any platform supported by GNU GNU Compiler Collection (GCC) or LLVM / Clang . Objective-C source code 'messaging/implementation' program files usually have .m filename extensions, while Objective-C 'header/interface' files have .h extensions,
6534-416: The kernel assurance that their work would benefit the whole world and remain free, rather than being exploited by software companies that would not have to give anything back to the community. In 2007, the third version of the license (GPLv3) was released to address some perceived problems with the second version (GPLv2) which were discovered during the latter's long-time usage. To keep the license current,
6633-536: The legal distinction between a license and a contract is an important one: contracts are enforceable by contract law , whereas licenses are enforced under copyright law . However, this distinction is not useful in the many jurisdictions where there are no differences between contracts and licenses, such as civil law systems. Those who do not accept the GPL's terms and conditions do not have permission, under copyright law, to copy or distribute GPL-licensed software or derivative works. However, if they do not redistribute
6732-420: The license. Copyleft applies only when a person seeks to redistribute the program. Developers may make private modified versions with no obligation to divulge the modifications, as long as they do not distribute the modified software to anyone else. Copyleft applies only to the software, and not to its output (unless that output is itself a derivative work of the program). For example, a public web portal running
6831-534: The machine level of CPUs and microcontrollers . Also, in the introduction chapter of The C Programming Language (second edition) by Brian Kernighan and Dennis Ritchie , C is described as "not a very high level" language. Assembly language may itself be regarded as a higher level (but often still one-to-one if used without macros ) representation of machine code , as it supports concepts such as constants and (limited) expressions, sometimes even variables, procedures, and data structures . Machine code , in turn,
6930-409: The main description of Objective-C in its original form in the book Object-Oriented Programming, An Evolutionary Approach . Although he was careful to explain that there is more to the problem of reusability than just what Objective-C provides, the language was often compared feature for feature with other languages. In 1988, NeXT licensed Objective-C from StepStone (the new name of PPI, the owner of
7029-431: The major change in GPLv2 was the "Liberty or Death" clause, as he calls it – Section 7. The section says that licensees may distribute a GPL-covered work only if they can satisfy all of the license's obligations, despite any other legal obligations they might have. In other words, the obligations of the license may not be severed due to conflicting obligations. This provision is intended to discourage any party from using
7128-450: The object is properly initialized by its superclass before the init method performs its initialization. It performs the following actions: A non-valid object pointer has the value nil ; conditional statements like if treat nil like a null pointer, so the initialization code will not be executed if [super init] returned nil. If there is an error in initialization the init method should perform any necessary cleanup, including sending
7227-453: The original author under copyright law. Copyright law has historically been used to prevent distribution of work by parties not authorized by the creator. Copyleft uses the same copyright laws to accomplish a very different goal. It grants rights to distribution to all parties insofar as they provide the same rights to subsequent ones, and they to the next, etc. In this way, the GPL and other copyleft licenses attempt to enforce libre access to
7326-509: The parties who would receive the covered work from you, a discriminatory patent license ... This aimed to make such future deals ineffective. The license was also meant to cause Microsoft to extend the patent licenses it granted to Novell customers for the use of GPLv3 software to all users of that GPLv3 software; this was possible only if Microsoft was legally a "conveyor" of the GPLv3 software. Early drafts of GPLv3 also let licensors add an AGPL -like requirement that would have plugged
7425-457: The perceived problems of a Microsoft–Novell style agreement, saying in Section 11 paragraph 6 that: You may not convey a covered work if you are a party to an arrangement with a third party that is in the business of distributing software, under which you make payment to the third party based on the extent of your activity of conveying the work, and under which the third party grants, to any of
7524-409: The preamble, though the preamble can be used in a modified license if permission to use it is obtained from the Free Software Foundation (FSF). According to the FSF, "The GPL does not require you to release your modified version or any part of it. You are free to make modifications and use them privately, without ever releasing them." However, if one releases a GPL-licensed entity to the public, there
7623-419: The process of developing a program simpler and more understandable than when using a lower-level language. The amount of abstraction provided defines how "high-level" a programming language is. In the 1960s, a high-level programming language using a compiler was commonly called an autocode . Examples of autocodes are COBOL and Fortran . The first high-level programming language designed for computers
7722-526: The program needs to be made available under the same license terms. The GNU Lesser General Public License (LGPL) was created to have a weaker copyleft than the GPL, in that it does not require custom-developed source code (distinct from the LGPL licensed parts) to be made available under the same license terms. The fifth section of version 3 states that no GPL-licensed code shall be considered an effective "technical protection measure" as defined by Article 11 of
7821-620: The programmer to be detached and separated from the machine. That is, unlike low-level languages like assembly or machine language, high-level programming can amplify the programmer's instructions and trigger a lot of data movements in the background without their knowledge. The responsibility and power of executing instructions have been handed over to the machine from the programmer. High-level languages intend to provide features that standardize common tasks, permit rich debugging, and maintain architectural agnosticism; while low-level languages often produce more efficient code through optimization for
7920-420: The public consultation process, 962 comments were submitted for the first draft. By the end of the comment period, a total of 2,636 comments had been submitted. The third draft was released on 28 March 2007. This draft included language intended to prevent patent-related agreements such as the controversial Microsoft-Novell patent agreement , and restricted the anti-tivoization clauses to a legal definition of
8019-408: The receiving object itself interpreting the message. A method is identified by a selector or SEL — a unique identifier for each message name, often just a NUL -terminated string representing its name — and resolved to a C method pointer implementing it: an IMP . A consequence of this is that the message-passing system has no type checking. The object to which the message is directed —
8118-426: The rights granted by the GPL". This forbids activities such as distributing the software under a non-disclosure agreement or contract. The fourth section for version 2 of the license and the seventh section of version 3 require that programs distributed as pre-compiled binaries be accompanied by a copy of the source code, a written offer to distribute the source code via the same mechanism as the pre-compiled binary, or
8217-566: The rights of the Free Software Definition . The licenses in the GPL series are all copyleft licenses, which means that any derivative work must be distributed under the same or equivalent license terms. It is more restrictive than the Lesser General Public License and even further distinct from the more widely-used permissive software licenses such as BSD , MIT , and Apache . Historically,
8316-451: The same as C header files. Objective-C++ files are denoted with a .mm file extension. Objective-C was created mainly by Brad Cox and Tom Love in the early 1980s at their company Productivity Products International (PPI) . Leading up to the creation of their company, both had been introduced to Smalltalk while at ITT Corporation 's Programming Technology Center in 1981. The earliest work on Objective-C traces back to around then. Cox
8415-440: The source code in obfuscated form, such as in cases in which the author is less willing to make the source code available. The consensus was that while unethical, it was not considered a violation. The issue was clarified when the license was altered with v2 to require that the "preferred" version of the source code be made available. The GPL was designed as a license , rather than a contract. In some common law jurisdictions,
8514-415: The syntax for non-object-oriented operations (including primitive variables, pre-processing, expressions, function declarations, and function calls) are identical to those of C, while the syntax for object-oriented features is an implementation of Smalltalk-style messaging. The Objective-C model of object-oriented programming is based on message passing to object instances. In Objective-C one does not call
8613-417: The terms of GPLv1 could be combined with software under more permissive terms, as this would not change the terms under which the whole could be distributed. However, software distributed under GPLv1 could not be combined with software distributed under a more restrictive license, as this would conflict with the requirement that the whole be distributable under the terms of GPLv1. According to Richard Stallman,
8712-446: The two main methods by which software distributors restricted the freedoms that define free software. The first problem was that distributors might publish only binary files that are executable, but not readable or modifiable by humans. To prevent this, GPLv1 stated that copying and distributing copies of any portion of the program must also make the human-readable source code available under the same licensing terms. The second problem
8811-549: The use of a lower-level language, even if a higher-level language would make the coding easier. In many cases, critical portions of a program mostly in a high-level language can be hand-coded in assembly language , leading to a much faster, more efficient, or simply reliably functioning optimised program . However, with the growing complexity of modern microprocessor architectures, well-designed compilers for high-level languages frequently produce code comparable in efficiency to what most low-level programmers can produce by hand, and
8910-515: The work and all derivatives. Many distributors of GPL licensed programs bundle the source code with the executables . An alternative method of satisfying the copyleft is to provide a written offer to provide the source code on a physical medium (such as a CD) upon request. In practice, many GPL licensed programs are distributed over the Internet, and the source code is made available over FTP or HTTP . For Internet distribution, this complies with
9009-510: The written offer to obtain the source code that the user got when they received the pre-compiled binary under the GPL. The second section of version 2 and the fifth section of version 3 also require giving "all recipients a copy of this License along with the Program". Version 3 of the license allows making the source code available in additional ways in fulfillment of the seventh section. These include downloading source code from an adjacent network server or by peer-to-peer transmission, provided that
9108-678: Was Plankalkül , created by Konrad Zuse . However, it was not implemented in his time, and his original contributions were largely isolated from other developments due to World War II , aside from the language's influence on the "Superplan" language by Heinz Rutishauser and also to some degree ALGOL . The first significantly widespread high-level language was Fortran , a machine-independent development of IBM's earlier Autocode systems. The ALGOL family, with ALGOL 58 defined in 1958 and ALGOL 60 defined in 1960 by committees of European and American computer scientists, introduced recursion as well as nested functions under lexical scope . ALGOL 60
9207-451: Was also the first language with a clear distinction between value and name-parameters and their corresponding semantics . ALGOL also introduced several structured programming concepts, such as the while-do and if-then-else constructs and its syntax was the first to be described in formal notation – Backus–Naur form (BNF). During roughly the same period, COBOL introduced records (also called structs) and Lisp introduced
9306-461: Was intrigued by problems of true reusability in software design and programming. He realized that a language like Smalltalk would be invaluable in building development environments for system developers at ITT. However, he and Tom Love also recognized that backward compatibility with C was critically important in ITT's telecom engineering milieu. Cox began writing a pre-processor for C to add some of
9405-439: Was introduced at the same time and numbered with version 2 to show that both were complementary. The version numbers diverged in 1999 when version 2.1 of the LGPL was released, which renamed it the GNU Lesser General Public License to reflect its place in the philosophy. The GPLv2 was also modified to refer to the new name of the LGPL, but its version number remained the same, resulting in the original GPLv2 not being recognised by
9504-420: Was led by Steve Naroff, who joined NeXT from StepStone. The compiler changes were made available as per GNU General Public License (GPL) terms, but the runtime libraries were not, rendering the open source contribution unusable to the general public. This led to other parties developing such runtime libraries under open source licenses. Later, Steve Naroff was also principal contributor to work at Apple to build
9603-426: Was that distributors might add restrictions, either to the license or by combining the software with other software that had other restrictions on distribution. The union of two sets of restrictions would apply to the combined work, thus adding unacceptable constrictions. To prevent this, GPLv1 stated that modified versions, as a whole, had to be distributed under the terms of GPLv1. Therefore, software distributed under
9702-594: Was to produce one license that could be used for any project, thus making it possible for many projects to share code. The second version of the license, version 2, was released in 1991. Over the following 15 years, members of the free software community became concerned over problems in the GPLv2 license that could let someone exploit GPL-licensed software in ways contrary to the license's intent. These problems included tivoization (the inclusion of GPL-licensed software in hardware that refuses to run modified versions of its software), compatibility issues similar to those of
9801-528: Was written by Richard Stallman in 1989, for use with programs released as part of the GNU project. It was based on a unification of similar licenses used for early versions of GNU Emacs (1985), the GNU Debugger , and the GNU C Compiler . These licenses contained similar provisions to the modern GPL, but were specific to each program, rendering them incompatible, despite being the same license. Stallman's goal
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