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Katherine Johnson’s mathematical calculations helped guide some of America’s most important early space missions while she confronted the racial and gender barriers faced by Black women in twentieth-century America.
MORE →Reflects the personal views, recollections, and perspective of the author, Mike Davis.
This is a personal recollection on the Move fire on May 13, 1985
The facade pattern (also spelled façade) is a software design pattern commonly used in object-oriented programming. Analogous to a façade in architecture, it is an object that serves as a front-facing interface masking more complex underlying or structural code. A facade can:
Developers often use the facade design pattern when a system is very complex or difficult to understand because the system has many interdependent classes or because its source code is unavailable. This pattern hides the complexities of the larger system and provides a simpler interface to the client. It typically involves a single wrapper class that contains a set of members required by the client. These members access the system on behalf of the facade client and hide the implementation details.
The Facade [1] design pattern is one of the twenty-three well-known GoF design patterns that describe how to solve recurring design problems to design flexible and reusable object-oriented software, that is, objects that are easier to implement, change, test, and reuse.
What problems can the Facade design pattern solve? [2]
Clients that access a complex subsystem directly refer to (depend on) many different objects having different interfaces (tight coupling), which makes the clients hard to implement, change, test, and reuse.
What solution does the Facade design pattern describe?
Define a Facade object that
This enables to work through a Facade object to minimize the dependencies on a subsystem.
See also the UML class and sequence diagram below.
A Facade is used when an easier or simpler interface to an underlying object is desired.[3] Alternatively, an adapter can be used when the wrapper must respect a particular interface and must support polymorphic behavior. A decorator makes it possible to add or alter behavior of an interface at run-time.
| Pattern | Intent |
|---|---|
| Adapter | Converts one interface to another so that it matches what the client is expecting |
| Decorator | Dynamically adds responsibility to the interface by wrapping the original code |
| Facade | Provides a simplified interface |
The facade pattern is typically used when
A good example of where a facade is used is in register indexed values like Modbus, I2C or Special function register.
In this UML class diagram,
the Client class doesn't access the subsystem classes directly.
Instead, the Client works through a Facade class that implements a simple interface in terms of (by delegating to) the subsystem classes (Class1, Class2, and Class3).
The Client depends only on the simple Facade interface
and is independent of the complex subsystem.[4]
The sequence diagram
shows the run-time interactions: The Client object
works through a Facade object that delegates the request to
the Class1, Class2, and Class3
instances that perform the request.
Source: Wikipedia. Article content is retrieved live through the MediaWiki API.
The facade pattern (also spelled façade) is a software design pattern commonly used in object-oriented programming. Analogous to a façade in architecture, it is an object that serves as a front-facing interface masking more complex underlying or structural code. A facade can: improve the readability and usability of a software library by masking interaction with more complex components behind a single (and often simplified) application programming interface (API) provide a context-specific interface to more generic functionality (complete with context-specific input validation) serve as a launching point for a broader refactor of monolithic or tightly-coupled systems in favor of more loosely-coupled code Developers often use the facade design pattern when a system is very complex or difficult to understand because the system has many interdependent classes or because its source code is unavailable. This pattern hides the complexities of the larger system and provides a simpler interface to the client. It typically involves a single wrapper class that contains a set of members required by the client. These members access the system on behalf of the facade client and hide the implementation details.
A façade is the exterior of a building. Facade, Façade, or Facades may also refer to: Facade constitutions Façade (entertainment), poems by Edith Sitwell set to music by William Walton Façade (ballet), a ballet by Frederick Ashton based on the Sitwell/Walton work, above Façade (video game), a 2005 independent experimental video game in the genre of interactive fiction Facade pattern, in programming, a structural pattern used alongside an API "Façade" (song), by Disturbed on the album Indestructible "Façade" (song), a 2023 song by Digga D and Potter Payper Facades (album), a 1979 album by Sad Café Facades, a composition by Philip Glass
Simple Logging Facade for Java (SLF4J) provides a Java logging API by means of a simple facade pattern. The underlying logging backend is determined at runtime by adding the desired binding to the classpath and may be the standard Sun Java logging package java.util.logging, Log4j, Reload4j, Logback or tinylog. The separation of the client API from the logging backend reduces the coupling between an application and any particular logging framework. This can make it easier to integrate with existing or third-party code or to deliver code into other projects that have already made a choice of logging backend. SLF4J was created by Ceki Gülcü as a more reliable alternative to Jakarta Commons Logging framework. Research in 2013 on 10,000 GitHub projects found that the most popular Java library is SLF4J, along with JUnit, with 30.7% of projects using it. In January 2021, it was ranked as the second most popular project according to mvnrepository.
In object-oriented programming, the singleton pattern is a software design pattern that restricts the instantiation of a class to a singular instance. It is one of the well-known "Gang of Four" design patterns, which describe how to solve recurring problems in object-oriented software. The pattern is useful when exactly one object is needed to coordinate actions across a system. More specifically, the singleton pattern allows classes to: Ensure they only have one instance Provide easy access to that instance Control their instantiation (for example, hiding the constructors of a class) The term comes from the mathematical concept of a singleton.
Before the 1921 destruction of Tulsa’s Greenwood District, Black residents had created a remarkable center of business and community life. The district included stores, professional offices, entertainment venues and homes owned by Black citizens. Understanding Greenwood means learning what was built—not only what was burned.
MORE →Joe Louis.
