32-841: [REDACTED] Look up Lua in Wiktionary, the free dictionary. Lua or LUA may refer to: Science and technology [ edit ] Lua (programming language) Latvia University of Agriculture Last universal common ancestor , in evolution, sometimes abbreviated as Lua Ethnicity and language [ edit ] Lua people , of Laos Lawa people , of Thailand sometimes referred to as Lua Lua language (disambiguation) , several languages (including Lua’) Luba-Kasai language , ISO 639 code Lai (surname) (賴), Chinese, sometimes romanised as Lua Places [ edit ] Tenzing-Hillary Airport (IATA code), in Lukla, Nepal One of
64-538: A double-hyphen and runs to the end of the line, similar to Ada , Eiffel , Haskell , SQL and VHDL . Multi-line strings and comments are marked with double square brackets. The factorial function is implemented in this example: Lua has one type of conditional test: if then end with optional else and elseif then execution control constructs. The generic if then end statement requires all three keywords: The else keyword may be added with an accompanying statement block to control execution when
96-502: A major influence on their decision to develop the table as the primary data structure of Lua. Lua semantics have been increasingly influenced by Scheme over time, especially with the introduction of anonymous functions and full lexical scoping . Several features were added in new Lua versions. Versions of Lua prior to version 5.0 were released under a license similar to the BSD license . From version 5.0 onwards, Lua has been licensed under
128-447: A parent object. There is no such concept as "class" with these techniques; rather, prototypes are used, similar to Self or JavaScript . New objects are created either with a factory method (that constructs new objects from scratch) or by cloning an existing object. Creating a basic vector object: Here, setmetatable tells Lua to look for an element in the Vector table if it
160-506: A prototype table, one can use function table : func ( args ) , which is equivalent to function table . func ( self , args ) . Calling class methods also makes use of the colon: object : func ( args ) is equivalent to object . func ( object , args ) . That in mind, here is a corresponding class with : syntactic sugar: Lua supports using metatables to give Lua class inheritance. In this example, we allow vectors to have their values multiplied by
192-441: A very diverse collection of computer platforms. Finally, since we expected that other Tecgraf products would also need to embed a scripting language, the new language should follow the example of SOL and be provided as a library with a C API. Lua 1.0 was designed in such a way that its object constructors, being then slightly different from the current light and flexible style, incorporated the data-description syntax of SOL (hence
224-435: Is a set of key and data pairs, where the data is referenced by key; in other words, it is a hashed heterogeneous associative array. Tables are created using the {} constructor syntax. Tables are always passed by reference (see Call by sharing ). A key (index) can be any value except nil and NaN , including functions. A table is often used as structure (or record ) by using strings as keys. Because such use
256-484: Is called, so that each new anonymous function returned will always access its own x parameter. The closure is managed by Lua's garbage collector, just like any other object. Tables are the most important data structures (and, by design, the only built-in composite data type ) in Lua and are the foundation of all user-created types. They are associative arrays with addition of automatic numeric key and special syntax. A table
288-854: Is different from Wikidata All article disambiguation pages All disambiguation pages Lua [REDACTED] Look up Lua in Wiktionary, the free dictionary. Lua or LUA may refer to: Science and technology [ edit ] Lua (programming language) Latvia University of Agriculture Last universal common ancestor , in evolution, sometimes abbreviated as Lua Ethnicity and language [ edit ] Lua people , of Laos Lawa people , of Thailand sometimes referred to as Lua Lua language (disambiguation) , several languages (including Lua’) Luba-Kasai language , ISO 639 code Lai (surname) (賴), Chinese, sometimes romanised as Lua Places [ edit ] Tenzing-Hillary Airport (IATA code), in Lukla, Nepal One of
320-416: Is different from Wikidata All article disambiguation pages All disambiguation pages Lua (programming language) Lua ( / ˈ l uː ə / LOO -ə ; from Portuguese : lua [ˈlu(w)ɐ] meaning moon ) is a lightweight , high-level , multi-paradigm programming language designed mainly for embedded use in applications. Lua is cross-platform software , since
352-455: Is distinct from a string key "1" . The length of a table t is defined to be any integer index n such that t[n] is not nil and t[n+1] is nil ; moreover, if t[1] is nil , n can be zero. For a regular array, with non-nil values from 1 to a given n , its length is exactly that n , the index of its last value. If the array has "holes" (that is, nil values between other non-nil values), then #t can be any of
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#1732845169568384-484: Is not present in the vec table. vec . magnitude , which is equivalent to vec [ "magnitude" ] , first looks in the vec table for the magnitude element. The vec table does not have a magnitude element, but its metatable delegates to the Vector table for the magnitude element when it's not found in the vec table. Lua provides some syntactic sugar to facilitate object orientation. To declare member functions inside
416-567: Is only about 247 kB compiled and easily adaptable to a broad range of applications. As a dynamically typed language intended for use as an extension language or scripting language , Lua is compact enough to fit on a variety of host platforms. It supports only a small number of atomic data structures such as Boolean values, numbers (double-precision floating point and 64-bit integers by default) and strings . Typical data structures such as arrays , sets , lists and records can be represented using Lua's single native data structure,
448-400: Is shown in the following example, where the print function's behavior is modified: Any future calls to print will now be routed through the new function, and because of Lua's lexical scoping , the old print function will only be accessible by the new, modified print. Lua also supports closures , as demonstrated below: A new closure for the variable x is created every time addto
480-406: Is very common, Lua features a special syntax for accessing such fields. By using a table to store related functions, it can act as a namespace. Tables are automatically assigned a numerical key, enabling them to be used as an array data type . The first automatic index is 1 rather than 0 as it is for many other programming languages (though an explicit index of 0 is allowed). A numeric key 1
512-578: The if condition evaluates to false : Execution may also be controlled according to multiple conditions using the elseif then keywords: Lua has four types of conditional loops: the while loop , the repeat loop (similar to a do while loop ), the numeric for loop and the generic for loop. This generic for loop would iterate over the table _G using the standard iterator function pairs , until it returns nil : Loops can also be nested (put inside of another loop). Lua's treatment of functions as first-class values
544-400: The n -th Fibonacci number using dynamic programming and memoization . Although Lua does not have a built-in concept of classes , object-oriented programming can be emulated using functions and tables. An object is formed by putting methods and fields in a table. Inheritance (both single and multiple) can be implemented with metatables , delegating nonexistent methods and fields to
576-575: The Duff Islands People [ edit ] Lua (goddess) , a Roman goddess Saint Lua (died c 609) Lua Blanco (born 1987), Brazilian actress and singer Lua Getsinger (1871–1916) A member of Weki Meki band Other uses [ edit ] Lua (martial art) , of Hawaii "Lua" (song) , by Bright Eyes See also [ edit ] Luas , a tram system in Dublin, Ireland LUAS (disambiguation) Topics referred to by
608-465: The Duff Islands People [ edit ] Lua (goddess) , a Roman goddess Saint Lua (died c 609) Lua Blanco (born 1987), Brazilian actress and singer Lua Getsinger (1871–1916) A member of Weki Meki band Other uses [ edit ] Lua (martial art) , of Hawaii "Lua" (song) , by Bright Eyes See also [ edit ] Luas , a tram system in Dublin, Ireland LUAS (disambiguation) Topics referred to by
640-574: The MIT License . Both are permissive free software licences and are almost identical. Lua is commonly described as a " multi-paradigm " language, providing a small set of general features that can be extended to fit different problem types. Lua does not contain explicit support for inheritance , but allows it to be implemented with metatables . Similarly, Lua allows programmers to implement namespaces , classes and other related features using its single table implementation; first-class functions allow
672-537: The Pontifical Catholic University of Rio de Janeiro , in Brazil . From 1977 until 1992, Brazil had a policy of strong trade barriers (called a market reserve) for computer hardware and software , believing that Brazil could and should produce its own hardware and software. In that climate, Tecgraf's clients could not afford, either politically or financially, to buy customized software from abroad; under
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#1732845169568704-551: The interpreter of compiled bytecode is written in ANSI C , and Lua has a relatively simple C application programming interface ( API ) to embed it into applications. Lua originated in 1993 as a language for extending software applications to meet the increasing demand for customization at the time. It provided the basic facilities of most procedural programming languages, but more complicated or domain-specific features were not included; rather, it included mechanisms for extending
736-426: The employment of many techniques from functional programming and full lexical scoping allows fine-grained information hiding to enforce the principle of least privilege . In general, Lua strives to provide simple, flexible meta-features that can be extended as needed, rather than supply a feature-set specific to one programming paradigm. As a result, the base language is light ; the full reference interpreter
768-535: The indices that directly precedes a nil value (that is, it may consider any such nil value as the end of the array). A table can be an array of objects. Using a hash map to emulate an array is normally slower than using an actual array; however, Lua tables are optimized for use as arrays to help avoid this issue. Extensible semantics is a key feature of Lua, and the metatable concept allows powerful customization of tables. The following example demonstrates an "infinite" table. For any n , fibs[n] will give
800-487: The language, allowing programmers to implement such features. As Lua was intended to be a general embeddable extension language, the designers of Lua focused on improving its speed , portability , extensibility and ease-of-use in development. Lua was created in 1993 by Roberto Ierusalimschy , Luiz Henrique de Figueiredo and Waldemar Celes, members of the Computer Graphics Technology Group (Tecgraf) at
832-576: The market reserve, clients would have to go through a complex bureaucratic process to prove their needs couldn't be met by Brazilian companies. Those reasons led Tecgraf to implement the basic tools it needed from scratch. Lua's predecessors were the data-description/configuration languages Simple Object Language (SOL) and data-entry language (DEL). They had been independently developed at Tecgraf in 1992–1993 to add some flexibility into two different projects (both were interactive graphical programs for engineering applications at Petrobras company). There
864-768: The name Lua: Sol meaning "Sun" in Portuguese, and Lua meaning "Moon"). Lua syntax for control structures was mostly borrowed from Modula ( if , while , repeat / until ), but also had taken influence from CLU (multiple assignments and multiple returns from function calls, as a simpler alternative to reference parameters or explicit pointers ), C++ ("neat idea of allowing a local variable to be declared only where we need it" ), SNOBOL and AWK ( associative arrays ). In an article published in Dr. Dobb's Journal , Lua's creators also state that LISP and Scheme with their single, ubiquitous data-structure mechanism (the list ) were
896-403: The same term [REDACTED] This disambiguation page lists articles associated with the title Lua . If an internal link led you here, you may wish to change the link to point directly to the intended article. Retrieved from " https://en.wikipedia.org/w/index.php?title=Lua&oldid=1257751463 " Category : Disambiguation pages Hidden categories: Short description
928-403: The same term [REDACTED] This disambiguation page lists articles associated with the title Lua . If an internal link led you here, you may wish to change the link to point directly to the intended article. Retrieved from " https://en.wikipedia.org/w/index.php?title=Lua&oldid=1257751463 " Category : Disambiguation pages Hidden categories: Short description
960-487: The table, which is essentially a heterogeneous associative array . Lua implements a small set of advanced features such as first-class functions , garbage collection , closures , proper tail calls , coercion (automatic conversion between string and number values at run time), coroutines (cooperative multitasking) and dynamic module loading . The classic "Hello, World!" program can be written as follows, with or without parentheses: A comment in Lua starts with
992-551: Was a lack of any flow-control structures in SOL and DEL, and Petrobras felt a growing need to add full programming power to them. In The Evolution of Lua , the language's authors wrote: In 1993, the only real contender was Tcl , which had been explicitly designed to be embedded into applications. However, Tcl had unfamiliar syntax, did not offer good support for data description, and ran only on Unix platforms. We did not consider LISP or Scheme because of their unfriendly syntax. Python
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1024-463: Was still in its infancy. In the free, do-it-yourself atmosphere that then reigned in Tecgraf, it was quite natural that we should try to develop our own scripting language ... Because many potential users of the language were not professional programmers, the language should avoid cryptic syntax and semantics. The implementation of the new language should be highly portable, because Tecgraf's clients had
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