Design patterns
0 likes165 views
This document discusses several topics related to software including programming languages, problems in the software industry, design patterns, and types of design patterns. It notes that programming languages have evolved from the first in 1943 to the latest in 2011. It also discusses early software project success rates and types of design patterns including creational, structural, behavioral, and concurrency patterns.
Design patterns
- 2. • Software Industry • Programing languages • Problem with software industry • What are design patterns? • Different type of design patterns
- 3. • Development, maintenance, publication of software and software services(such as training, documentation, and consulting) • Software as a service, or SaaS – 21st century trend to reduce the piracy of software by providing everything on web rather than client side installation • Infrastructure software, including operating systems, middleware, and databases • Software that automates business processes
- 4. • A programming language is a notation for writing programs, which are specifications of a computation or algorithm • A programming language's surface form is known as its syntax • The term Semantics refers to the meaning of languages, as opposed to their form • First programming language was designed in 1943, and latest in 2011 (Dart) • Assembly, Algorithmic, Functional, System, Logic, Generic, Scripting and Object Oriented Programing languages
- 5. • Very less success rate • 1994 – 18% • 2001 – 28% • 2003 – 31% • 2008 • Iterative – 71% • Agile – 70% • Traditional – 66% • Ad-Hoc – 62%
- 6. • A design pattern is not a finished design that can be transformed directly into code • It is a description or template for how to solve a problem that can be used in many different situations • The design patterns may just be a sign of some missing features of a given programming language • Inappropriate use of patterns may unnecessarily increase complexity • There is no single, standard format for documenting design patterns • Erich Gamma, Richard Helm, Ralph Johnson and John Vlissides is called “Gang of Four” or GoF
- 7. • Creational patterns • Deal with object creation mechanisms • Includes 9 design patterns like Singleton & Factory method • Structural patterns • Ease the design by identifying a simple way to realize relationships between entities • Includes 9 design patterns like Decorator & Façade
- 8. • Behavioral patterns • Identify common communication patterns between objects • Includes 15 design patterns like Chain of responsibility & Iterator • Concurrency patterns • Deal with multi-threaded programming paradigm • Includes 14 design patterns like Thread pool & Lock