In
software object-oriented design
Object-oriented design (OOD) is the process of planning a system of interacting objects for the purpose of solving a software problem. It is one approach to software design.
Overview
An object contains encapsulated data and procedures grouped t ...
, a layer is a group of
class
Class or The Class may refer to:
Common uses not otherwise categorized
* Class (biology), a taxonomic rank
* Class (knowledge representation), a collection of individuals or objects
* Class (philosophy), an analytical concept used differently ...
es that have the same set of link-time
module
Module, modular and modularity may refer to the concept of modularity. They may also refer to:
Computing and engineering
* Modular design, the engineering discipline of designing complex devices using separately designed sub-components
* Modul ...
dependencies to other modules. In other words, a layer is a group of reusable
components that are
reusable in similar circumstances. In programming languages, the layer distinction is often expressed as "import" dependencies between software modules.
Layers are often arranged in a
tree-form
hierarchy, with dependency relationships as links between the layers. Dependency relationships between layers are often either
inheritance
Inheritance is the practice of receiving private property, titles, debts, entitlements, privileges, rights, and obligations upon the death of an individual. The rules of inheritance differ among societies and have changed over time. Officiall ...
,
composition
Composition or Compositions may refer to:
Arts and literature
*Composition (dance), practice and teaching of choreography
*Composition (language), in literature and rhetoric, producing a work in spoken tradition and written discourse, to include v ...
or
aggregation relationships, but other kinds of dependencies can also be used.
Layers is an
architectural pattern
An architectural pattern is a general, reusable solution to a commonly occurring problem in software architecture within a given context. The architectural patterns address various issues in software engineering, such as computer hardware perform ...
described in many books, for example ''Pattern-Oriented Software Architecture''
Pattern-Oriented Software Architecture - A System of Patterns
See also
* Abstraction layer
In computing, an abstraction layer or abstraction level is a way of hiding the working details of a subsystem. Examples of software models that use layers of abstraction include the OSI model for network protocols, OpenGL, and other graphics librar ...
* Multitier architecture
* Shearing layers
Shearing layers is a concept coined by architect Frank Duffy, which was later elaborated by Stewart Brand in his book, '' How Buildings Learn: What Happens After They're Built'' (Brand, 1994), and refers to buildings as composed of several layers ...
References
Object-oriented programming
Software design
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