Editing Library (computing) (section)

== Categories ==

=== Executable ===

An executable library consists of code that has been converted from source code into [[machine code]] or an intermediate form such as [[bytecode]]. A linker allows for using library objects by associating each reference with an address at which the object is located. For example, in [[C (programming language)|C]], a library function is invoked via C's normal function call [[Syntax (programming languages)|syntax]] and [[Semantics (computer science)|semantics]].<ref>{{Cite thesis|title=Metamorphic Detection Using Function Call Graph Analysis|publisher=San Jose State University Library|first=Prasad|last=Deshpande| year=2013 |doi=10.31979/etd.t9xm-ahsc|doi-access=free}}</ref>

A variant is a library containing compiled code (object code in IBM's nomenclature) in a form that cannot be loaded by the OS but that can be read by the linker.

===Static===
A [[static library]] is an executable library that is linked into a program at build-time by a linker (or whatever the build tool is called that does linking).<ref name="Static Libraries">{{cite web|title=Static Libraries|url=http://tldp.org/HOWTO/Program-Library-HOWTO/static-libraries.html|publisher=TLDP|access-date=3 October 2013|url-status=live|archive-url=https://web.archive.org/web/20130703011904/http://tldp.org/HOWTO/Program-Library-HOWTO/static-libraries.html|archive-date=3 July 2013}}</ref><ref>{{cite book|last=Kaminsky|first=Dan|chapter=Chapter 3 - Portable Executable and Executable and Linking Formats|date=2008|chapter-url=http://dx.doi.org/10.1016/b978-1-59749-237-9.00003-x|title=Reverse Engineering Code with IDA Pro|pages=37–66|publisher=Elsevier|doi=10.1016/b978-1-59749-237-9.00003-x|isbn=978-1-59749-237-9|access-date=2021-05-27}}</ref> This process, and the resulting stand-alone file, is known as a [[static build]] of the program. A static build may not need any further [[relocation (computer science)|relocation]] if [[virtual memory]] is used and no [[address space layout randomization]] is desired.<ref>{{cite conference|url=http://usenix.org/legacy/publications/library/proceedings/usenix05/tech/general/full_papers/collberg/collberg_html/main.html|title=SLINKY: Static Linking Reloaded|conference=USENIX '05|first1=Christian |last1=Collberg |first2=John H. |last2=Hartman |first3=Sridivya |last3=Babu |first4=Sharath K. |last4=Udupa|publisher=Department of Computer Science, [[University of Arizona]]|access-date=2016-03-17|year=2003|url-status=live|archive-url=https://web.archive.org/web/20160323214637/https://www.usenix.org/legacy/publications/library/proceedings/usenix05/tech/general/full_papers/collberg/collberg_html/main.html|archive-date=23 March 2016}}</ref>

A static library is sometimes called an ''archive'' on Unix-like systems.

===Dynamic===

A [[dynamic library]] is linked when the program is run {{endash}} either at [[load-time]] or [[Runtime (program lifecycle phase)|runtime]]. The dynamic library was intended after the static library to support additional [[software deployment]] flexibility.

===Source===
A source library consists of source code; not compiled code. 

===Shared===
A [[shared library]] is a library that contains [[executable code]] designed to be used by multiple [[computer program]]s or other [[library (computing)|libraries]] at [[Runtime (program lifecycle phase)|runtime]], with only one copy of that code in memory, shared by all programs using the code.<ref>{{cite book |title=Linkers and Loaders |last=Levine |first=John R. |chapter=9. Shared Libraries |isbn=1-55860-496-0 |date=2000}}</ref><ref>{{cite book |title=UNIX System V/386 Release 3.2 Programmers Guide, Vol. 1 |url=http://www.bitsavers.org/pdf/att/unix/System_V_386_Release_3.2/UNIX_System_V_386_Release_3.2_Programmers_Guide_Vol1_1989.pdf |page=8{{hyp}}2 |isbn=0-13-944877-2 |date=1989|publisher=Prentice Hall }}</ref><ref>{{cite web |url=https://www.cs.cornell.edu/courses/cs414/2001FA/sharedlib.pdf |title=Shared Libraries in SunOS |pages=1,3}}</ref>

===Object===

Although generally an obsolete technology today, an object library exposes resources for [[object-oriented programming]] (OOP) and a distributed object is a remote object library. Examples include: [[Component Object Model|COM]]/DCOM, [[System Object Model|SOM]]/DSOM, [[Distributed Objects Everywhere|DOE]], [[Portable Distributed Objects|PDO]] and various [[CORBA]]-based systems.

The object library technology was developed since as OOP became popular, it became apparent that OOP runtime binding required information than contemporary libraries did not provide. In addition to the names and entry points of the code located within, due to inheritance, OOP binding also requires a list of dependencies {{endash}} since the full definition of a method may be in different places. Further, this requires more than listing that one library requires the services of another. In OOP, the libraries themselves may not be known at [[compile time]], and vary from system to system.

The remote object technology was developed in parallel to support multi-tier programs with a [[user interface]] application running on a [[personal computer]] (PC) using services of a [[Mainframe computer|mainframe]] or [[minicomputer]] such as data storage and processing. For instance, a program on a PC would send messages to a minicomputer via [[remote procedure call]] (RPC) to retrieve relatively small samples from a relatively large dataset. In response, distrubuted object technology was developed.

===Class===

A class library contains [[Class (computer science)|classes]] that can be used to create [[object (computer science)|objects]]. In [[Java (programming language)|Java]], for example, classes are contained in [[jar (file format)|JAR files]] and objects are created at runtime from the classes. However, in [[Smalltalk]], a class library is the starting point for a [[system image]] that includes the entire state of the environment, classes and all instantiated objects. Most class libraries are stored in a [[package repository]] (such as Maven Central for Java). Client code explicitly specifies dependencies to external libraries in build configuration files (such as a Maven Pom in Java).

===Remote===
A remote library runs on another computer and its assets are accessed via [[remote procedure call]] (RPC) over a network. This [[Distributed computing|distributed architecture]] allows for minimizing installation of the library and support for it on each consuming system and ensuring consistent versioning. A significant downside is that each library call entails significantly more overhead than for a local library.

=== Runtime ===
A [[runtime library]] provides access to the [[runtime environment]] that is available to a program {{endash}} tailored to the host [[computer platform|platform]].

=== Language standard ===
Many modern [[programming languages]] specify a [[standard library]] that provides a base level of functionality for the language environment.

===Code generation===
A code generation library has a high-level [[Application Programming Interface|API]] generating or transforming [[byte code]] for [[Java (programming language)|Java]]. They are used by [[aspect-oriented programming]], some data access frameworks, and for testing to generate dynamic proxy objects. They also are used to intercept field access.<ref>{{cite web
 |access-date  = 2010-03-03
 |publisher   = [[Source Forge]]
 |title       = Code Generation Library
 |url         = https://sourceforge.net/projects/cglib/
 |quote       = Byte Code Generation Library is high level API to generate and transform JAVA byte code. It is used by AOP, testing, data access frameworks to generate dynamic proxy objects and intercept field access.
 |url-status     = live
 |archive-url  = https://web.archive.org/web/20100112154306/http://sourceforge.net/projects/cglib/
 |archive-date = 12 January 2010
}}</ref>