In programming and software design, binding is an application programming interface (API) that provides glue code specifically made to allow a programming language to use a foreign library or operating system service (one that is not native to that language).


Binding generally refers to a mapping of one thing to another. In the context of software libraries, bindings are wrapper libraries that bridge two programming languages, so that a library written for one language can be used in another language.[1] Many software libraries are written in system programming languages such as C or C++. To use such libraries from another language, usually of higher-level, such as Java, Common Lisp, Scheme, Python, or Lua, a binding to the library must be created in that language, possibly requiring recompiling the language's code, depending on the amount of modification needed.[2] However, most languages offer a foreign function interface, such as Python's and OCaml's ctypes, and Embeddable Common Lisp's cffi and uffi.[3][4][5]

For example, Python bindings are used when an extant C library, written for some purpose, is to be used from Python. Another example is libsvn which is written in C to provide an API to access the Subversion software repository. To access Subversion from within Java code, libsvnjavahl can be used, which depends on libsvn being installed and acts as a bridge between the language Java and libsvn, thus providing an API that invokes functions from libsvn to do the work.[6]

Major motives to create library bindings include software reuse, to reduce reimplementing a library in several languages, and the difficulty of implementing some algorithms efficiently in some high-level languages.

Runtime environment

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Object models

Further information: Object model

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Virtual machines

Further information: Virtual machine

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Further information: Porting

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See also

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  1. ^ "Appendix A. Creating a language binding for cairo". Retrieved 2014-04-02.
  2. ^ "Standards, APIs, Interfaces and Bindings". Archived from the original on 2015-01-16. Retrieved 2014-04-02.
  3. ^ "ctypes – A foreign function library for Python". Python v3.8.3 documentation. Retrieved 2020-06-04.
  4. ^ Hickey, Jason; Madhavapeddy, Anil; Minsky, Yaron (2013). "Real Worl OCaml, Chapter 19. Foreign Function Interface". Retrieved 2015-07-19.
  5. ^ "Introduction – CFFI User Manual". Retrieved 2014-04-02.
  6. ^ "Subversion JavaHL FAQ". 2013-06-18. Retrieved 2014-04-02.