Design by contract known as contract programming, programming by contract and design-by-contract programming, is an approach for designing software. It prescribes that software designers should define formal and verifiable interface specifications for software components, which extend the ordinary definition of abstract data types with preconditions and invariants; these specifications are referred to as "contracts", in accordance with a conceptual metaphor with the conditions and obligations of business contracts. The DbC approach assumes all client components that invoke an operation on a server component will meet the preconditions specified as required for that operation. Where this assumption is considered too risky the inverse approach is taken, meaning that the server component tests that all relevant preconditions hold true and replies with a suitable error message if not; the term was coined by Bertrand Meyer in connection with his design of the Eiffel programming language and first described in various articles starting in 1986 and the two successive editions of his book Object-Oriented Software Construction.
Eiffel Software applied for trademark registration for Design by Contract in December 2003, it was granted in December 2004. The current owner of this trademark is Eiffel Software. Design by contract has its roots in work on formal verification, formal specification and Hoare logic; the original contributions include: A clear metaphor to guide the design process The application to inheritance, in particular a formalism for redefinition and dynamic binding The application to exception handling The connection with automatic software documentation The central idea of DbC is a metaphor on how elements of a software system collaborate with each other on the basis of mutual obligations and benefits. The metaphor comes from business life, where a "client" and a "supplier" agree on a "contract" that defines, for example, that: The supplier must provide a certain product and is entitled to expect that the client has paid its fee; the client is entitled to get the product. Both parties must satisfy certain obligations, such as laws and regulations, applying to all contracts.
If the method of a class in object-oriented programming provides a certain functionality, it may: Expect a certain condition to be guaranteed on entry by any client module that calls it: the method's precondition—an obligation for the client, a benefit for the supplier, as it frees it from having to handle cases outside of the precondition. Guarantee a certain property on exit: the method's postcondition—an obligation for the supplier, a benefit for the client. Maintain a certain property, assumed on entry and guaranteed on exit: the class invariant; the contract is semantically equivalent to a Hoare triple. This can be summarised by the "three questions" that the designer must answer in the contract: What does the contract expect? What does the contract guarantee? What does the contract maintain? Many programming languages have facilities to make assertions like these. However, DbC considers these contracts to be so crucial to software correctness that they should be part of the design process.
In effect, DbC advocates writing the assertions first. Contracts can be written by code comments, enforced by a test suite, or both if there is no special language support for contracts; the notion of a contract extends down to the method/procedure level. These rules approximate behavioural subtyping. All class relationships are between client classes and supplier classes. A client class is obliged to make calls to supplier features where the resulting state of the supplier is not violated by the client call. Subsequently, the supplier is obliged to provide a return state and data that does not violate the state requirements of the client. For instance, a supplier data buffer may require that data is present in the buffer when a delete feature is called. Subsequently, the supplier guarantees to the client that when a delete feature finishes its work, the data item will, indeed, be deleted from the buffer. Other design contracts are concepts of class invariant; the class invariant guarantees that the state of the class will be maintained within specified tolerances at the end of each feature execution.
When using contracts, a supplier should not try to verify that the contract conditions are satisfied—a practice known as offensive programming—the general idea being that code should "fail hard", with contract verification being the safety net. DbC's "fail hard" property simplifies the debugging of contract behavior, as the intended behaviour of each method is specified; this approach differs from that of defensive programming, where the supplier is responsible for figuring out what to do when a precondition is broken. More than not, the supplier throws an exception to inform the client that the precondition has been broken, in both cases—DbC and defen
St James' Church Paddington known as St James' Church Sussex Gardens, is a Church of England parish church in Paddington, London, in the United Kingdom. It is the parish church of Paddington, it is located at the western end of Sussex Gardens, a long tree-lined avenue, about 175 metres north of Hyde Park. Until the 1840s, the parish church of Paddington was St Mary's Paddington Green; this building was too small to accommodate its burgeoning congregation, in 1841–1843 a new church, St James's, was built to accommodate the worshippers and to replace St Mary's as the parish church. The original St James's church was designed by John Goldicutt but was finished by George Gutch after Goldicutt's death. Goldicutt's original scheme was for a neo-classical design in yellow brick, influenced by his travels in Italy; the yellow brick was used but Gutch changed the style to Gothic. Within 40 years the congregation had outgrown its church building, an enlarged church was required; the noted Gothic Revival architect G.
E. Street planned extensive rebuilding, which involved retaining part of Goldicutt & Gutch's structure and remodelling the church in a 14th-century Gothic style. Unusually, Street reversed the traditional orientation of the church so that the chancel faced west rather than east, as is traditional in church architecture. Street did not live to see his plans for St James's realised as he died on 18 December 1881, before construction started. Two months after Street's death, the Princess Christian of Schleswig-Holstein laid the foundation stone for the new church on 11 February 1882. and the building work was carried out by Sir Arthur Blomfield, an associate of G. E. Street's son, A. E. Street. On 29 May 1884, the Irish author Oscar Wilde married Constance Lloyd in St James's Church; this event is commemorated with a circular wall plaque, at the east end of the church. The plaque, commissioned by the Oscar Wilde Society, was designed in Welsh slate by the letter cutter & stone carver Tom Sargeant and unveiled at a ceremony on 29 May 2016, to mark the 132nd anniversary of the wedding.
In 1940, during World War II, St James's Church suffered considerable damage during the Blitz and the church crypt was used as an air-raid shelter. After wartime bomb damage has been repaired, the renovated church was -reopened in July 1958 by Princess Marina, Duchess of Kent. Renovations to the church included new stained glass windows; the Te Deum Window at the east end commemorates a selection of notable historical figures who lived in the Parish of St James, including the biologist and inventor of penicillin, Alexander Fleming. M. Barrie; the window depicts a scene from the Blitz, commemorating those who died during the Battle of Britain. The organ was built by William Hill & Sons and installed in 1882; the instrument has been revoiced several times in its history. It was rebuilt in 1936 by Rushworth and Dreaper of Liverpool, again in 1972 ny J. W. Walker & Sons Ltd. A specification of the organ can be found on the National Pipe Organ Register. Parish website A Church Near You entry
The National Museum of Contemporary Art is an art museum located in the Chiado neighbourhood of Lisbon, Portugal. It was created in 1911 and re-inaugurated, in new installations, in 1994; the museum covers the period between 1850 and 1950, with works by the foremost Portuguese artists of the period, as well as some foreigners. It holds the best collection of Portuguese painting and sculpture from the Romanticism and Modern periods. Among the artists represented are António Silva Porto, António Carneiro, António Soares dos Reis, Miguel Ângelo Lupi, Columbano Bordalo Pinheiro, Amadeo de Souza Cardoso, Abel Manta, Dórdio Gomes, Adriano Sousa Lopes, José de Almada Negreiros, Nadir Afonso, Mário Eloy, Francisco Augusto Metrass, Auguste Rodin, many others; the museum hosts temporary exhibitions. Since 1911, the Chiado Museum has occupied part of the old Convent of São Francisco in Lisbon, a building of mediaeval origin; the 1994 adaptation and renovation of the museum areas were done by French architect Jean-Michel Wilmotte.
Chiado Museum official website The National Museum of Contemporary Art on Google Arts & Culture Chiado Museum website
USS Enterprise CVA-65, is a decommissioned United States Navy aircraft carrier. She was the first nuclear-powered aircraft carrier and the eighth United States naval vessel to bear the name. Like her predecessor of World War II fame, she is nicknamed "Big E". At 1,088 feet, she is one of the longest naval vessels built, her 93,284-long-ton displacement ranks her as the 12th-heaviest carrier, after the ten carriers of the Nimitz class and USS Gerald R. Ford. Enterprise had a crew of some 4,600 service members; the only ship of her class, Enterprise was, at the time of deactivation, the third-oldest commissioned vessel in the United States Navy after the wooden-hulled USS Constitution and USS Pueblo. She was deactivated on 1 December 2012, decommissioned on 3 February 2017, after over 55 years of service, she was stricken from the Naval Vessel Register the same day. The name has been adopted by the future Gerald R. Ford-class aircraft carrier USS Enterprise. Enterprise was intended as the first of a class of six carriers, but massive increases in construction costs led to the remaining vessels being cancelled.
Because of the huge cost of her construction, Enterprise was launched and commissioned without the planned RIM-2 Terrier missile launchers. These were never installed and the ship's self-defense suite instead consisted of three shorter-range RIM-7 Sea Sparrow, Basic Point Defense Missile System launchers. Upgrades added two NATO Sea Sparrow and three Mk 15 Phalanx CIWS gun mounts. One CIWS mount was removed and two 21-cell RIM-116 Rolling Airframe Missile launchers were added. Enterprise is the only aircraft carrier to house more than two nuclear reactors, having an eight-reactor propulsion design, with each A2W reactor taking the place of one of the conventional boilers in earlier constructions, she is the only carrier with four rudders, two more than other classes, features a more cruiser-like hull. Enterprise had a phased array radar system known as SCANFAR. SCANFAR was intended to be better at tracking multiple airborne targets than conventional rotating antenna radars. SCANFAR consisted of two radars, the AN/SPS-32 and the AN/SPS-33.
The AN/SPS-32 was a long-range air search and target acquisition radar developed by Hughes for the U. S. Navy; the AN/SPS-32 operated together with the AN/SPS-33, the square array used for 3D tracking, into one system. It was installed on only two vessels and the cruiser USS Long Beach, placing a massive power drain on the ship's electric system; the technology of the AN/SPS -32 was based on the system required constant repairs. The SPS-32 was a phased array radar which had a range of 400 nautical miles against large targets, 200 nautical miles against small, fighter-size targets; these early phased arrays, replaced around 1980, were responsible for the distinctive square-looking island. The AN/SPS-32 and AN/SPS-33 radars, while ahead of their time, suffered from issues relating to electrical beam steering mechanism and were not pursued in further ship classes. While they are considered to be an early form of "phased array" radar, it would take the technology of the Aegis phased array AN/SPY-1 with its electronically controlled beam steering to make phased array radars both reliable and practical for the USN.
The dome above the SCANFAR contained the unique electronic warfare suite, the Andrew Alford AA-8200 dipole antennas. The system consisted of six rows of antennae encircling the dome; the antennae in the upper two rows were encased in piping radomes as they were fragile. In 1958, Enterprise's keel was laid at Newport News Shipbuilding and Drydock Company in Shipway 11. On 24 September 1960, the ship was launched, sponsored by Mrs. W. B. Franke, wife of the former Secretary of the Navy. On 25 November 1961, Enterprise was commissioned, with Captain Vincent P. de Poix of Fighting Squadron 6 on her predecessor, in command. On 12 January 1962, the ship made her maiden voyage conducting a three-month shakedown cruise and a lengthy series of tests and training exercises designed to determine the full capabilities of the nuclear powered super carrier. On 20 February 1962, Enterprise was a tracking and measuring station for the flight of Friendship 7, the Project Mercury space capsule in which Lieutenant Colonel John H. Glenn, Jr. made the first American orbital spaceflight.
In August, the carrier joined the 6th Fleet in the Mediterranean Sea, returning to Norfolk, Virginia in October. In October 1962, Enterprise was dispatched to her first international crisis. Following revelations that the Soviet Union was constructing nuclear missile launch sites on Cuba, President John F. Kennedy ordered the United States Department of Defense to conduct a large-scale buildup. Among the preparations, the U. S. Atlantic Fleet readied large numbers of its ships. On 22 October, President Kennedy ordered a naval and air "quarantine" on shipment of offensive military equipment to Cuba, demanded the Soviets dismantle the missile sites there. Five United States Second Fleet carriers participated in the blockade—Enterprise, Essex, Lake Champlain, Randolph, backed by shore-based aircraft. By 28 October, the crisis was averted, after the United States secretly agreed to remove nuclear missiles from Italy and Turkey. On 19 December 1962, a Grumman E-2 Hawkeye was catapulted off Enterprise in the first shipboard test of a nose-wheel launch bar designed to replace the catapult bridle.
Minutes a second launch with a launch bar was made by a Grumman A-6A Intruder, demonstrating one of the primary design goals of reducing launch intervals. In 1963–1964, now under command of Captain Frederick H. Michae
Sofala is a province of Mozambique. It has a population of 2,259,248. Beira is the capital of the province, named for the ruined port of Sofala, 35 kilometres to the south. Portuguese landholder and imperialist Joaquim Carlos Paiva de Andrada established a base at the river mouth at what is now Beira in 1884. Sofala Province is one of the strongholds of the RENAMO. In late 1978 RENAMO guerrillas were "ranging into Sofala Province and launching attacks along the Beira–Chimoio road and rail line, the Dondo–Inhaminga corridor"; some of the more scarcely populated areas of the province are affected by landmines. In March 2019, the province was affected by Cyclone Idai, with its capital city of Beira being destroyed; the flooding resulting from this storm was widespread throughout the province and the rest of Central Mozambique. Sofala Province, in central-eastern Mozambique, covers an area of 68,018 square kilometres; the province is bordered to the north by Tete Province, to the northeast by Zambezia Province, to the south by Inhambane Province, to the west by Manica Province.
Rivers flowing through the province include the Chiveve River, the Buzi River, the Save River, which flows along the Inhambane provincial border, the Púnguè River, which flows into the sea at Beira. On the Urema River, a tributary of the Púnguè, the river forms the lagoon which are home to hundreds of hippopotamus; the valleys of the province are subject to flooding. Gorongosa National Park, at the southern end of the Great African Rift Valley, covers several thousand square kilometres, including the valley floor and parts of surrounding forested plateaus, which contain miombo and montane forests; the park contains the 1,863 metres Mount Gorongosa, a mountain, considered sacred to the people of the country. On the eastern slope of the mountain is a number of vegetation zones according to elevation, there are numerous limestone caves in the vicinity. Sofala Province is divided into the 12 districts of: Buzi District Caia District Chemba District Cheringoma District Chibabava District Dondo District Gorongosa District Marromeu District Machanga District Maringué District Muanza District Nhamatanda District The city of Beira, the provincial capital and Mozambique's second-largest city and the busiest port in the country, plays a key role in the local economy.
Principal exports include ores, food products, cotton and skins, with the chief imports including fertilizers and textiles, liquid fuels and wheat. The Mozambique Company had their headquarters in Beira, during the building of the railway across the country. Many buildings remain from the colonial period, it is "as famed for its seafood as for its tawdry nightlife"; the Makuti Lighthouse of Beira was built in 1904. The oil trade has been important to the regional economy, with Beira connected by pipeline to Zimbabwe in 1960; the port of Beira is crucial for the trade in oil involving Zimbabwe, Malawi and Congo. In the 21st century, agricultural productivity in the province has shown significant improvement, reducing poverty; the Austrian Development Cooperation has played a major role in investment in the province. Province of Sofala official site
The State Theatre is a venue for the performing arts and entertainment, located in downtown Eau Claire, Wisconsin with seating for 1100 people. The original State Theatre, built in 1925, is a large two-story brick Art Deco building designed by Joseph E. Nason. An addition was added in 1936, it is on the state and national register of historic buildings. The venue opened on January 19, 1926, as a vaudeville theater several years converted to a movie house that closed in 1982. In 1984 the Theatre was donated to a group of arts-minded community members called the Eau Claire Regional Arts Council to create a center for artistic expression. After a significant renovation it reopened the doors in 1986. During the ECRAC period it was used by a number of local performing arts organizations including: Chippewa Valley Symphony, Chippewa Valley Theatre Guild, Chippewa Valley Youth Choirs, Eau Claire Children's Theatre, Valley Gospel Choir, UW - Eau Claire, it closed in July 2018. The venue was leased to Luginbill children's foundation.
The venue reopened in October 2019 as the State Theatre and Community Center, with Joe Luginbill serving as CEO. On January 25th, 2019, it was announced that utilities to the State Theatre and Community Center had been cut off, due to a $20,000 debt. WPT Presents: History of Eau Claire's State Theatre The State Theatre and Community Center official Facebook page