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Double Dispatch
In software engineering, double dispatch is a special form of multiple dispatch, and a mechanism that dispatches a function call to different concrete functions depending on the runtime types of two objects involved in the call. In most object-oriented systems, the concrete function that is called from a function call in the code depends on the dynamic type of a single object and therefore they are known as single dispatch calls, or simply virtual function calls. Dan Ingalls first described how to use double dispatching in Smalltalk, calling it multiple polymorphism. Overview The general problem addressed is how to dispatch a message to different methods depending not only on the receiver but also on the arguments. To that end, systems like CLOS implement multiple dispatch. Double dispatch is another solution that gradually reduces the polymorphism on systems that do not support multiple dispatch. Use cases Double dispatch is useful in situations where the choice of computation ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Software Engineering
Software engineering is a branch of both computer science and engineering focused on designing, developing, testing, and maintaining Application software, software applications. It involves applying engineering design process, engineering principles and computer programming expertise to develop software systems that meet user needs. The terms ''programmer'' and ''coder'' overlap ''software engineer'', but they imply only the construction aspect of a typical software engineer workload. A software engineer applies a software development process, which involves defining, Implementation, implementing, Software testing, testing, Project management, managing, and Software maintenance, maintaining software systems, as well as developing the software development process itself. History Beginning in the 1960s, software engineering was recognized as a separate field of engineering. The development of software engineering was seen as a struggle. Problems included software that was over ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Name Mangling
In compiler construction, name mangling (also called name decoration) is a technique used to solve various problems caused by the need to resolve unique names for programming entities in many modern programming languages. It provides means to encode added information in the name of a function, structure, class or another data type, to pass more semantic information from the compiler to the linker. The need for name mangling arises where a language allows different entities to be named with the same identifier as long as they occupy a different namespace (typically defined by a module, class, or explicit ''namespace'' directive) or have different type signatures (such as in function overloading). It is required in these uses because each signature might require different, specialized calling convention in the machine code. Any object code produced by compilers is usually linked with other pieces of object code (produced by the same or another compiler) by a type of program c ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Software Design Patterns
In software engineering, a software design pattern or design pattern is a general, reusable solution to a commonly occurring problem in many contexts in software design. A design pattern is not a rigid structure to be transplanted directly into source code. Rather, it is a description or a template for solving a particular type of problem that can be deployed in many different situations. Design patterns can be viewed as formalized best practices that the programmer may use to solve common problems when designing a software application or system. Object-oriented design patterns typically show relationships and interactions between classes or objects, without specifying the final application classes or objects that are involved. Patterns that imply mutable state may be unsuited for functional programming languages. Some patterns can be rendered unnecessary in languages that have built-in support for solving the problem they are trying to solve, and object-oriented patterns are no ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Virtual Table
In computer programming, a virtual method table (VMT), virtual function table, virtual call table, dispatch table, vtable, or vftable is a mechanism used in a programming language to support dynamic dispatch (or run-time method binding). Whenever a class defines a virtual function (or method), most compilers add a hidden member variable to the class that points to an array of pointers to (virtual) functions called the virtual method table. These pointers are used at runtime to invoke the appropriate function implementations, because at compile time it may not yet be known if the base function is to be called or a derived one implemented by a class that inherits from the base class. There are many different ways to implement such dynamic dispatch, but use of virtual method tables is especially common among C++ and related languages (such as D and C#). Languages that separate the programmatic interface of objects from the implementation, like Visual Basic and Delphi, als ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hash Function
A hash function is any Function (mathematics), function that can be used to map data (computing), data of arbitrary size to fixed-size values, though there are some hash functions that support variable-length output. The values returned by a hash function are called ''hash values'', ''hash codes'', (''hash/message'') ''digests'', or simply ''hashes''. The values are usually used to index a fixed-size table called a ''hash table''. Use of a hash function to index a hash table is called ''hashing'' or ''scatter-storage addressing''. Hash functions and their associated hash tables are used in data storage and retrieval applications to access data in a small and nearly constant time per retrieval. They require an amount of storage space only fractionally greater than the total space required for the data or records themselves. Hashing is a computationally- and storage-space-efficient form of data access that avoids the non-constant access time of ordered and unordered lists and s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Multiple Dispatch
Multiple dispatch or multimethods is a feature of some programming languages in which a Subroutine, function or Method (computer programming), method can be dynamic dispatch, dynamically dispatched based on the run time (program lifecycle phase), run-time (dynamic) type or, in the more general case, some other attribute of more than one of its Parameter (computer programming), arguments. This is a generalization of single-dispatch polymorphism in object-oriented programming, polymorphism where a function or method call is dynamically dispatched based on the derived type of the object on which the method has been called. Multiple dispatch routes the dynamic dispatch to the implementing function or method using the combined characteristics of one or more arguments. Understanding dispatch Developers of computer software typically organize source code into named blocks variously called subroutines, procedures, subprograms, functions, or methods. The code in the function is executed b ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Visitor Pattern
A visitor pattern is a software design pattern that separates the algorithm from the object structure. Because of this separation, new operations can be added to existing object structures without modifying the structures. It is one way to follow the open/closed principle in object-oriented programming and software engineering. In essence, the visitor allows adding new virtual functions to a family of classes, without modifying the classes. Instead, a visitor class is created that implements all of the appropriate specializations of the virtual function. The visitor takes the instance reference as input, and implements the goal through double dispatch. Programming languages with sum types and pattern matching obviate many of the benefits of the visitor pattern, as the visitor class is able to both easily branch on the type of the object and generate a compiler error if a new object type is defined which the visitor does not yet handle. Overview The Visitor design pattern i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Static Type Checking
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 a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Reflection (computer Science)
In computer science, reflective programming or reflection is the ability of a process to examine, introspect, and modify its own structure and behavior. Historical background The earliest computers were programmed in their native assembly languages, which were inherently reflective, as these original architectures could be programmed by defining instructions as data and using self-modifying code. As the bulk of programming moved to higher-level compiled languages such as ALGOL, COBOL, Fortran, Pascal, and C, this reflective ability largely disappeared until new programming languages with reflection built into their type systems appeared. Brian Cantwell Smith's 1982 doctoral dissertation introduced the notion of computational reflection in procedural programming languages and the notion of the meta-circular interpreter as a component of 3-Lisp. Uses Reflection helps programmers make generic software libraries to display data, process different formats of data, perform se ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Eiffel (programming Language)
Eiffel is an object-oriented programming language designed by Bertrand Meyer (an object-orientation proponent and author of '' Object-Oriented Software Construction'') and Eiffel Software. Meyer conceived the language in 1985 with the goal of increasing the reliability of commercial software development. The first version was released in 1986. In 2005, the International Organization for Standardization (ISO) released a technical standard for Eiffel. The design of the language is closely connected with the Eiffel programming method. Both are based on a set of principles, including design by contract, command–query separation, the uniform-access principle, the single-choice principle, the open–closed principle, and option–operand separation. Many concepts initially introduced by Eiffel were later added into Java, C#, and other languages. New language design ideas, particularly through the Ecma/ ISO standardization process, continue to be incorporated into the Eiffe ... [...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] |
Visitor Pattern
A visitor pattern is a software design pattern that separates the algorithm from the object structure. Because of this separation, new operations can be added to existing object structures without modifying the structures. It is one way to follow the open/closed principle in object-oriented programming and software engineering. In essence, the visitor allows adding new virtual functions to a family of classes, without modifying the classes. Instead, a visitor class is created that implements all of the appropriate specializations of the virtual function. The visitor takes the instance reference as input, and implements the goal through double dispatch. Programming languages with sum types and pattern matching obviate many of the benefits of the visitor pattern, as the visitor class is able to both easily branch on the type of the object and generate a compiler error if a new object type is defined which the visitor does not yet handle. Overview The Visitor design pattern i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
