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Null Object
In object-oriented computer programming, a null object is an object with no referenced value or with defined neutral (''null'') behavior. The null object design pattern, which describes the uses of such objects and their behavior (or lack thereof), was first published as "Void Value" and later in the ''Pattern Languages of Program Design'' book series as "Null Object" . Motivation In most object-oriented languages, such as Java or C#, references may be null. These references need to be checked to ensure they are not null before invoking any methods, because methods typically cannot be invoked on null references. The Objective-C language takes another approach to this problem and does nothing when sending a message to nil; if a return value is expected, nil (for objects), 0 (for numeric values), NO (for BOOL values), or a struct (for struct types) with all its members initialised to null/0/NO/zero-initialised struct is returned. Description Instead of using a null reference ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Object-oriented
Object-oriented programming (OOP) is a programming paradigm based on the concept of "objects", which can contain data and code. The data is in the form of fields (often known as attributes or ''properties''), and the code is in the form of procedures (often known as ''methods''). A common feature of objects is that procedures (or methods) are attached to them and can access and modify the object's data fields. In this brand of OOP, there is usually a special name such as or used to refer to the current object. In OOP, computer programs are designed by making them out of objects that interact with one another. OOP languages are diverse, but the most popular ones are class-based, meaning that objects are instances of classes, which also determine their types. Many of the most widely used programming languages (such as C++, Java, Python, etc.) are multi-paradigm and they support object-oriented programming to a greater or lesser degree, typically in combination with impera ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Martin Fowler (software Engineer)
Martin Fowler (18 December 1963) is a British software developer, author and international public speaker on software development, specialising in object-oriented analysis and design, UML, patterns, and agile software development methodologies, including extreme programming. His 1999 book ''Refactoring'' popularised the practice of code refactoring. In 2004 he introduced a new architectural pattern, called Presentation Model (PM). Biography Fowler was born and grew up in Walsall, England, where he went to Queen Mary's Grammar School for his secondary education. He graduated at University College London in 1986. In 1994 he moved to the United States, where he lives near Boston, Massachusetts in the suburb of Melrose.Martin Fowler at martinfowler.com. Retrieved 2012-11-15. Fowler started working with software in the early 1980s. Out of un ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nullable Type
Nullable types are a feature of some programming languages which allow a value to be set to the special value NULL instead of the usual possible values of the data type. In statically typed languages, a nullable type is an option type, while in dynamically typed languages (where values have types, but variables do not), equivalent behavior is provided by having a single null value. NULL is frequently used to represent a missing value or invalid value, such as from a function that failed to return or a missing field in a database, as in NULL in SQL. In other words NULL is undefined. Primitive types such as integers and Booleans cannot generally be null, but the corresponding nullable types (nullable integer and nullable Boolean, respectively) can also assume the NULL value. This can be represented in ternary logic as FALSE,NULL,TRUE as in three-valued logic. Example An integer variable may represent integers, but 0 (zero) is a special case because 0 in many programming language ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Singleton Pattern
In software engineering, the singleton pattern is a software design pattern that restricts the instantiation of a class to a singular instance. 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 objects 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. Common uses Singletons are often preferred to global variables because they do not pollute the global namespace (or their containing namespace). Additionally, they permit lazy allocation and initialization, whereas global variables in many languages will always consume resources. The singleton pattern can also be used as a basis for oth ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Reference Type
In computer programming, data types can be divided into two categories: value types (or by-value types) and reference types (or by-reference types). Value types are completely represented by their meaning, while reference types are references to another value. Value types A value is a fully self-describing piece of data. Equal values are indistinguishable at during program runtime. That is, they lack identity. For example, in the C++ and Java programming languages, the integer literal is a value. It is indistinguishable from any other at runtime, and there is no way to mutate the literal to be a different value such as . In many programming languages, value types are often represented and stored in an efficient manner. For example, booleans, fixed-size integers, and fixed-size floating-point types may be compactly stored and passed in the registers of the CPU. Reference types Reference types are represented as a reference to another value, which may itself be either a va ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
JavaScript
JavaScript (), often abbreviated as JS, is a programming language that is one of the core technologies of the World Wide Web, alongside HTML and CSS. As of 2022, 98% of Website, websites use JavaScript on the Client (computing), client side for Web page, webpage behavior, often incorporating third-party Library (computing), libraries. All major Web browser, web browsers have a dedicated JavaScript engine to execute the Source code, code on User (computing), users' devices. JavaScript is a High-level programming language, high-level, often Just-in-time compilation, just-in-time compiled language that conforms to the ECMAScript standard. It has dynamic typing, Prototype-based programming, prototype-based object-oriented programming, object-orientation, and first-class functions. It is Programming paradigm, multi-paradigm, supporting Event-driven programming, event-driven, functional programming, functional, and imperative programming, imperative programming paradigm, programmin ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Monkey Patch
Monkey patching is a technique used to dynamically update the behavior of a piece of code at run-time. A monkey patch (also spelled monkey-patch, MonkeyPatch) is a way to extend or modify the runtime code of dynamic languages (e.g. Smalltalk, JavaScript, Objective-C, Ruby, Perl, Python, Groovy, etc.) without altering the original source code. Etymology The term ''monkey patch'' seems to have come from an earlier term, ''guerrilla patch'', which referred to changing code sneakily – and possibly incompatibly with other such patches – at runtime. The word '' guerrilla'', nearly homophonous with ''gorilla'', became ''monkey'', possibly to make the patch sound less intimidating. An alternative etymology is that it refers to “monkeying about” with the code (messing with it). Despite the name's suggestion, the "monkey patch" is sometimes the official method of extending a program. For example, web browsers such as Firefox and Internet Explorer used to encourage this, although ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ruby (programming Language)
Ruby is an interpreted, high-level, general-purpose programming language which supports multiple programming paradigms. It was designed with an emphasis on programming productivity and simplicity. In Ruby, everything is an object, including primitive data types. It was developed in the mid-1990s by Yukihiro "Matz" Matsumoto in Japan. Ruby is dynamically typed and uses garbage collection and just-in-time compilation. It supports multiple programming paradigms, including procedural, object-oriented, and functional programming. According to the creator, Ruby was influenced by Perl, Smalltalk, Eiffel, Ada, BASIC, Java and Lisp. History Early concept Matsumoto has said that Ruby was conceived in 1993. In a 1999 post to the ''ruby-talk'' mailing list, he describes some of his early ideas about the language: Matsumoto describes the design of Ruby as being like a simple Lisp language at its core, with an object system like that of Smalltalk, blocks inspired by higher-o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Duck Typing
Duck typing in computer programming is an application of the duck test—"If it walks like a duck and it quacks like a duck, then it must be a duck"—to determine whether an object can be used for a particular purpose. With nominative typing, an object is ''of a given type'' if it is declared to be (or if a type's association with the object is inferred through mechanisms such as object inheritance). In duck typing, an object is ''of a given type'' if it has all methods and properties required by that type. Duck typing can be viewed as a usage-based structural equivalence between a given object and the requirements of a type. See structural typing for a further explanation of structural type equivalence. Example This is a simple example in Python 3 that demonstrates how any object may be used in any context, up until it is used in a way that it does not support. class Duck: def swim(self): print("Duck swimming") def fly(self): print("Duck flyi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Null Coalescing Operator
The null coalescing operator (called the Logical Defined-Or operator in Perl) is a binary operator that is part of the syntax for a basic conditional expression in several programming languages, including C#, PowerShell as of version 7.0.0, Perl as of version 5.10, Swift, and PHP 7.0.0. While its behavior differs between implementations, the null coalescing operator generally returns the result of its left-most operand if it exists and is not null, and otherwise returns the right-most operand. This behavior allows a default value to be defined for cases where a more specific value is not available. In contrast to the ternary conditional if operator used as x ? x : y, but like the binary Elvis operator used as x ?: y, the null coalescing operator is a binary operator and thus evaluates its operands at most once, which is significant if the evaluation of x has side-effects. Examples by languages Bourne-like Shells In Bourne shell (and derivatives), "If ''parameter'' is uns ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Extension Method
In object-oriented computer programming, an extension method is a method added to an object after the original object was compiled. The modified object is often a class, a prototype or a type. Extension methods are features of some object-oriented programming languages. There is no syntactic difference between calling an extension method and calling a method declared in the type definition. Not all languages implement extension methods in an equally safe manner, however. For instance, languages such as C#, Java (viManifoldoLombok, and Kotlin don't alter the extended class in any way, because doing so may break class hierarchies and interfere with virtual method dispatching. This is why these languages strictly implement extension methods statically and use static dispatching to invoke them. Support in programming languages Extension methods are features of numerous languages including C#, Java viManifoldoLombok Gosu, JavaScript, Oxygene, Ruby, Smalltalk, Kotlin, Dart, Vis ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Microsoft
Microsoft Corporation is an American multinational technology corporation producing computer software, consumer electronics, personal computers, and related services. Headquartered at the Microsoft campus in Redmond, Washington, Microsoft's best-known software products are the Windows line of operating systems, the Microsoft Office suite, and the Internet Explorer and Edge web browsers. Its flagship hardware products are the Xbox video game consoles and the Microsoft Surface lineup of touchscreen personal computers. Microsoft ranked No. 21 in the 2020 Fortune 500 rankings of the largest United States corporations by total revenue; it was the world's largest software maker by revenue as of 2019. It is one of the Big Five American information technology companies, alongside Alphabet, Amazon, Apple, and Meta. Microsoft was founded by Bill Gates and Paul Allen on April 4, 1975, to develop and sell BASIC interpreters for the Altair 8800. It rose to dominate the personal comp ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
