Layer (object-oriented design)

In <a href="/facts/Software/RP79lVSW">software</a> <a href="/facts/Object-oriented_design/erWk0mUW">object-oriented design</a>, a layer is a group of <a href="/facts/Class_(computer_science)/zvzkSAtE">classes</a> that have the same set of link-time <a href="/facts/Module_(programming)/sNoqKvRD">module</a> <a href="/facts/Dependency_(computer_science)/QEeSaXF3">dependencies</a> to other modules. In other words, a layer is a group of reusable <a href="/facts/Software_componentry/eW5wvSHC">components</a> that are <a href="/facts/Reusability/te10mWEI">reusable</a> in similar circumstances. In programming languages, the layer distinction is often expressed as "import" dependencies between software modules.
Layers are often arranged in a <a href="/facts/Tree_(data_structure)/RcXz9noF">tree</a>-form <a href="/facts/Hierarchy/mYJyqFrG">hierarchy</a>, with dependency relationships as links between the layers. Dependency relationships between layers are often either <a href="/facts/Inheritance_(object-oriented_programming)/a7R1xv8n">inheritance</a>, <a href="/facts/Object_composition/zWbRC9Jd">composition</a> or <a href="/facts/Object_composition/zWbRC9Jd">aggregation</a> relationships, but other kinds of dependencies can also be used.
Layers is an <a href="/facts/Architectural_pattern_(computer_science)/GnN0z06K">architectural pattern</a> described in many books, for example Pattern-Oriented Software Architecture

Layer (object-oriented design) open-in-new

Layer (object-oriented design)