Modular programming

Modular programming is a software design technique that increases the extent to which software is composed from separate parts, called modules. Conceptually, modules represent a separation of concerns, and improve maintainability by enforcing logical boundaries between components. Modules are typically incorporated into the program through interfaces. A module interface expresses the elements that are provided and required by the module. The elements defined in the interface are detectable by other modules. The implementation contains the working code that corresponds to the elements declared in the interface.

Languages that formally support the module concept include IBM/360 Assembler for an assembly language, COBOL, RPG and PL/1, Ada, D, F, Fortran, Haskell, OCaml, Pascal, ML, Modula-2, Erlang, Perl, Python and Ruby. The IBM System i also uses Modules in RPG, COBOL and CL, when programming in the ILE environment. Modular programming can be performed even where the programming language lacks explicit syntactic features to support named modules.

Software tools can create modular code units from groups of components. Libraries of components built from separately compiled modules can be combined into a whole by using a linker.

Module Interconnection Languages

Module interconnection languages (MILs) provide formal grammar constructs for deciding the various module interconnection specifications required to assemble a complete software system. MILs enable the separation between programming-in-the-small and programming-in-the-large. Coding a module represents programming in the small, while assembling a system with the help of a MIL represents programming in the large. An example of MIL is MIL-75.

See Object-Oriented Software Construction, Second Edition [1] chapter 3 - Modularity

See also

• Architecture description language
• Cohesion
• Constructionist design methodology, a methodology for creating modular, broad Artificial Intelligence systems
• Component-based software engineering
• Coupling
• David Parnas
• Information hiding (encapsulation)
• Library (computing)
• List of System Quality Attributes
• Snippet (programming)
• Structured programming