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Pure Virtual Class
In programming languages, an abstract type (also known as existential types) is a Type (computer science), type in a nominative type system that cannot be Instance (computer science), instantiated directly; by contrast, a concrete type be instantiated directly. Instantiation of an abstract type can occur only indirectly, via a concrete Subtyping, ''subtype''. An abstract type may provide no implementation, or an incomplete implementation. In some languages, abstract types with no implementation (rather than an incomplete implementation) are known as ''Protocol (object-oriented programming), protocols'', ''interfaces'', ''signatures'', or ''class types''. In Class-based programming, class-based object-oriented programming, abstract types are implemented as ''abstract class, abstract classes'' (also known as ''abstract base classes''), and concrete types as ''concrete classes''. In generic programming, the analogous notion is a Concept (generic programming), ''concept'', which s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Programming Languages
A programming language is a system of notation for writing computer programs. Programming languages are described in terms of their syntax (form) and semantics (meaning), usually defined by a formal language. Languages usually provide features such as a type system, variables, and mechanisms for error handling. An implementation of a programming language is required in order to execute programs, namely an interpreter or a compiler. An interpreter directly executes the source code, while a compiler produces an executable program. Computer architecture has strongly influenced the design of programming languages, with the most common type ( imperative languages—which implement operations in a specified order) developed to perform well on the popular von Neumann architecture. While early programming languages were closely tied to the hardware, over time they have developed more abstraction to hide implementation details for greater simplicity. Thousands of programming langua ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Template Method Pattern
In object-oriented programming, the template method is one of the behavioral pattern, behavioral Software design pattern, design patterns identified by Gamma et al. in the book ''Design Patterns''. The template method is a method in a superclass, usually an abstract superclass, and defines the skeleton of an operation in terms of a number of high-level steps. These steps are themselves implemented by additional ''helper methods'' in the same class as the ''template method''. The ''helper methods'' may be either ''abstract methods'', in which case subclasses are required to provide concrete implementations, or ''Hooking, hook methods,'' which have empty bodies in the superclass. Subclass (computer science), Subclasses can (but are not required to) customize the operation by Method overriding, overriding the hook methods. The intent of the template method is to define the overall structure of the operation, while allowing subclasses to refine, or redefine, certain steps. Overvi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dynamic Typing
In computer programming, a type system is a logical system comprising a set of rules that assigns a property called a ''type'' (for example, integer, floating point, string) to every '' term'' (a word, phrase, or other set of symbols). Usually the terms are various language constructs of a computer program, such as variables, expressions, functions, or modules. A type system dictates the operations that can be performed on a term. For variables, the type system determines the allowed values of that term. Type systems formalize and enforce the otherwise implicit categories the programmer uses for algebraic data types, data structures, or other data types, such as "string", "array of float", "function returning boolean". Type systems are often specified as part of programming languages and built into interpreters and compilers, although the type system of a language can be extended by optional tools that perform added checks using the language's original type syntax ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
UML Class Pet
The Unified Modeling Language (UML) is a general-purpose visual modeling language that is intended to provide a standard way to visualize the design of a system. UML provides a standard notation for many types of diagrams which can be roughly divided into three main groups: behavior diagrams, interaction diagrams, and structure diagrams. The creation of UML was originally motivated by the desire to standardize the disparate notational systems and approaches to software design. It was developed at Rational Software in 1994–1995, with further development led by them through 1996. In 1997, UML was adopted as a standard by the Object Management Group (OMG) and has been managed by this organization ever since. In 2005, UML was also published by the International Organization for Standardization (ISO) and the International Electrotechnical Commission (IEC) as the ISO/IEC 19501 standard. Since then the standard has been periodically revised to cover the latest revision of UML. In ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Objective-C
Objective-C is a high-level general-purpose, object-oriented programming language that adds Smalltalk-style message passing (messaging) to the C programming language. Originally developed by Brad Cox and Tom Love in the early 1980s, it was selected by NeXT for its NeXTSTEP operating system. Due to Apple macOS’s direct lineage from NeXTSTEP, Objective-C was the standard language used, supported, and promoted by Apple for developing macOS and iOS applications (via their respective application programming interfaces ( APIs), Cocoa and Cocoa Touch) from 1997, when Apple purchased NeXT until the introduction of the Swift language in 2014. Objective-C programs developed for non-Apple operating systems or that are not dependent on Apple's APIs may also be compiled for any platform supported by GNU GNU Compiler Collection (GCC) or LLVM/ Clang. Objective-C source code 'messaging/implementation' program files usually have filename extensions, while Objective-C 'header/ ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
This (computer Science)
this, self, and Me are keywords used in some computer programming languages to refer to the object, class, or other entity which the currently running code is a part of. The entity referred to thus depends on the execution context (such as which object has its method called). Different programming languages use these keywords in slightly different ways. In languages where a keyword like "this" is mandatory, the keyword is the only way to access data and methods stored in the current object. Where optional, these keywords can disambiguate variables and functions with the same name. Object-oriented programming In many object-oriented programming languages, this (also called self or Me) is a variable that is used in instance methods to refer to the object on which they are working. The first OO language, SIMULA 67, used this to explicitly reference the local object. C++ and languages which derive in style from it (such as Java, C#, D, and PHP) also generally use this. Small ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Inheritance (object-oriented Programming)
In object-oriented programming, inheritance is the mechanism of basing an Object (computer science), object or Class (computer programming), class upon another object (Prototype-based programming, prototype-based inheritance) or class (Class-based programming, class-based inheritance), retaining similar implementation. Also defined as deriving new classes (#Subclasses and superclasses, sub classes) from existing ones such as super class or Fragile base class, base class and then forming them into a hierarchy of classes. In most class-based object-oriented languages like C++, an object created through inheritance, a "child object", acquires all the properties and behaviors of the "parent object", with the exception of: Constructor (object-oriented programming), constructors, destructors, operator overloading, overloaded operators and friend functions of the base class. Inheritance allows programmers to create classes that are built upon existing classes, to specify a new implementat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Virtual Functions
In object-oriented programming such as is often used in C++ and Object Pascal, a virtual function or virtual method is an inheritable and overridable function or method that is dispatched dynamically. Virtual functions are an important part of (runtime) polymorphism in object-oriented programming (OOP). They allow for the execution of target functions that were not precisely identified at compile time. Most programming languages, such as JavaScript, PHP and Python, treat all methods as virtual by default and do not provide a modifier to change this behavior. However, some languages provide modifiers to prevent methods from being overridden by derived classes (such as the ''final'' and ''private'' keywords in Java and PHP). Purpose The concept of the virtual function solves the following problem: In object-oriented programming, when a derived class inherits from a base class, an object of the derived class may be referred to via a pointer or reference of the base clas ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
C Sharp (programming Language)
C# ( pronounced: C-sharp) ( ) is a general-purpose high-level programming language supporting multiple paradigms. C# encompasses static typing, strong typing, lexically scoped, imperative, declarative, functional, generic, object-oriented (class-based), and component-oriented programming disciplines. The principal inventors of the C# programming language were Anders Hejlsberg, Scott Wiltamuth, and Peter Golde from Microsoft. It was first widely distributed in July 2000 and was later approved as an international standard by Ecma (ECMA-334) in 2002 and ISO/ IEC (ISO/IEC 23270 and 20619) in 2003. Microsoft introduced C# along with .NET Framework and Microsoft Visual Studio, both of which are technically speaking, closed-source. At the time, Microsoft had no open-source products. Four years later, in 2004, a free and open-source project called Microsoft Mono began, providing a cross-platform compiler and runtime environment for the C# programming language. A decad ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
D (programming Language)
D, also known as dlang, is a multi-paradigm system programming language created by Walter Bright at Digital Mars and released in 2001. Andrei Alexandrescu joined the design and development effort in 2007. Though it originated as a re-engineering of C++, D is now a very different language. As it has developed, it has drawn inspiration from other high-level programming languages. Notably, it has been influenced by Java, Python, Ruby, C#, and Eiffel. The D language reference describes it as follows: Features D is not source-compatible with C and C++ source code in general. However, any code that is legal in both C/C++ and D should behave in the same way. Like C++, D has closures, anonymous functions, compile-time function execution, design by contract, ranges, built-in container iteration concepts, and type inference. D's declaration, statement and expression syntaxes also closely match those of C++. Unlike C++, D also implements garbage collection, first cl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
