Language binding

In programming and software design, a 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).

Characteristics

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

Object models

Further information: Object model

• Common Object Request Broker Architecture (CORBA) – cross-platform-language model
• Component Object Model (COM) – Microsoft Windows only cross-language model
  • Distributed Component Object Model (DCOM) – extension enabling COM to work over networks
  • Cross Platform Component Object Model (XPCOM) – Mozilla applications cross-platform model
• Common Language Infrastructure – .NET Framework cross-platform-language model
• Freedesktop.org D-Bus – open cross-platform-language model

Virtual machines

Further information: Virtual machine

• Comparison of application virtual machines

Porting

Further information: Porting

• Portable object – cross-platform-language object model definition

See also

• Computer programming portal

• Application programming interface (API)
• Application binary interface (ABI)
• Calling convention
• Embedded SQL
• Name mangling
• Simplified Wrapper and Interface Generator (SWIG) – interface binding generator from many languages to many languages, open-source
• Wrapper function