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Law Of Demeter
The Law of Demeter (LoD) or principle of least knowledge is a design guideline for developing software, particularly object-oriented programs. In its general form, the LoD is a specific case of loose coupling. The guideline was proposed by Ian Holland at Northeastern University towards the end of 1987, and the following three recommendations serve as a succinct summary: * Each unit should have only limited knowledge about other units: only units "closely" related to the current unit. * Each unit should only talk to its friends; don't talk to strangers. * Only talk to your immediate friends. The fundamental notion is that a given object should assume as little as possible about the structure or properties of anything else (including its subcomponents), in accordance with the principle of "information hiding". It may be viewed as a corollary to the principle of least privilege, which dictates that a module possess only the information and resources necessary for its legitimate purp ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Software
Software is a set of computer programs and associated documentation and data. This is in contrast to hardware, from which the system is built and which actually performs the work. At the lowest programming level, executable code consists of machine language instructions supported by an individual processor—typically a central processing unit (CPU) or a graphics processing unit (GPU). Machine language consists of groups of binary values signifying processor instructions that change the state of the computer from its preceding state. For example, an instruction may change the value stored in a particular storage location in the computer—an effect that is not directly observable to the user. An instruction may also invoke one of many input or output operations, for example displaying some text on a computer screen; causing state changes which should be visible to the user. The processor executes the instructions in the order they are provided, unless it is instructed ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Analogy
Analogy (from Greek ''analogia'', "proportion", from ''ana-'' "upon, according to" lso "against", "anew"+ ''logos'' "ratio" lso "word, speech, reckoning" is a cognitive process of transferring information or meaning from a particular subject (the analog, or source) to another (the target), or a linguistic expression corresponding to such a process. In a narrower sense, analogy is an inference or an argument from one particular to another particular, as opposed to deduction, induction, and abduction, in which at least one of the premises, or the conclusion, is general rather than particular in nature. The term analogy can also refer to the relation between the source and the target themselves, which is often (though not always) a similarity, as in the biological notion of analogy. Analogy plays a significant role in problem solving, as well as decision making, argumentation, perception, generalization, memory, creativity, invention, prediction, emotion, explanation, concep ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Principle Of Least Astonishment
The principle of least astonishment (POLA), aka principle of least surprise (alternatively a law or rule), applies to user interface and software design. It proposes that a component of a system should behave in a way that most users will expect it to behave. The behavior should not astonish or surprise users. The following is a formal statement of the principle: "If a necessary feature has a high astonishment factor, it may be necessary to redesign the feature." The term has been in use in relation to computer use since at least the 1970s. Although first formalized in the field of computer technology, the principle can be applied broadly in other fields. For example, in writing, a cross-reference to another part of the work or a hyperlink should be phrased in a way that accurately tells the reader what to expect. In a book about fishing for bass, "For recipes on how to cook your catch, see chapter 4" should not lead the reader to a chapter about bass fishing seasons in various lo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Single-responsibility Principle
The single-responsibility principle (SRP) is a computer programming principle that states that "A module should be responsible to one, and only one, actor." The term actor refers to a group (consisting of one or more stakeholders or users) that requires a change in the module. Robert C. Martin, the originator of the term, expresses the principle as, "A class should have only one reason to change". Because of confusion around the word "reason" he has also clarified saying that the "principle is about people." In some of his talks, he also argues that the principle is, in particular, about roles or actors. For example, while they might be the same person, the role of an accountant is different from a database administrator. Hence, each module should be responsible for each role. History The term was introduced by Robert C. Martin in his article "The Principles of OOD" as part of his ''Principles of Object Oriented Design'', made popular by his 2003 book ''Agile Software Developmen ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Wrapper Method
A wrapper function is a function (another word for a ''subroutine'') in a software library or a computer program whose main purpose is to call a second subroutine or a system call with little or no additional computation. Wrapper functions are used to make writing computer programs easier by abstracting away the details of a subroutine's underlying implementation. Purpose Wrapper functions are a means of delegation and can be used for a number of purposes. Programming convenience Wrapper functions can be used to make writing computer programs easier. An example of this is the MouseAdapter and similar classes in the Java AWT library. Wrapper functions are useful in the development of applications that use third-party library functions. A wrapper can be written for each of the third party functions and used in the native application. In case the third party functions change or are updated, only the wrappers in the native application need to be modified as opposed to changing ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Layer (object-oriented Design)
In software object-oriented design, a layer is a group of classes that have the same set of link-time module dependencies to other modules. In other words, a layer is a group of reusable components that are reusable in similar circumstances. In programming languages, the layer distinction is often expressed as "import" dependencies between software modules. Layers are often arranged in a tree-form hierarchy, with dependency relationships as links between the layers. Dependency relationships between layers are often either inheritance, composition or aggregation relationships, but other kinds of dependencies can also be used. Layers is an architectural pattern described in many books, for example ''Pattern-Oriented Software Architecture'' [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Multilayered Architecture
In software engineering, multitier architecture (often referred to as ''n''-tier architecture) is a client–server architecture in which presentation, application processing and data management functions are physically separated. The most widespread use of multitier architecture is the three-tier architecture. ''N''-tier application architecture provides a model by which developers can create flexible and reusable applications. By segregating an application into tiers, developers acquire the option of modifying or adding a specific tier, instead of reworking the entire application. A three-tier architecture is typically composed of a ''presentation'' tier, a ''logic'' tier, and a ''data'' tier. While the concepts of layer and tier are often used interchangeably, one fairly common point of view is that there is indeed a difference. This view holds that a ''layer'' is a logical structuring mechanism for the conceptual elements that make up the software solution, while a ''tier'' ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Software Bug
A software bug is an error, flaw or fault in the design, development, or operation of computer software that causes it to produce an incorrect or unexpected result, or to behave in unintended ways. The process of finding and correcting bugs is termed " debugging" and often uses formal techniques or tools to pinpoint bugs. Since the 1950s, some computer systems have been designed to deter, detect or auto-correct various computer bugs during operations. Bugs in software can arise from mistakes and errors made in interpreting and extracting users' requirements, planning a program's design, writing its source code, and from interaction with humans, hardware and programs, such as operating systems or libraries. A program with many, or serious, bugs is often described as ''buggy''. Bugs can trigger errors that may have ripple effects. The effects of bugs may be subtle, such as unintended text formatting, through to more obvious effects such as causing a program to crash, freezing th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Software Configuration Management
In software engineering, software configuration management (SCM or S/W CM) is the task of tracking and controlling changes in the software, part of the larger cross-disciplinary field of configuration management. SCM practices include revision control and the establishment of baselines. If something goes wrong, SCM can determine the "what, when, why and who" of the change. If a configuration is working well, SCM can determine how to replicate it across many hosts. The acronym "SCM" is also expanded as source configuration management process and software change and configuration management. However, "configuration" is generally understood to cover changes typically made by a system administrator. Purposes The goals of SCM are generally: *Configuration identification - Identifying configurations, configuration items and baselines. *Configuration control - Implementing a controlled change process. This is usually achieved by setting up a change control board whose primary ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Coupling (computer Programming)
In software engineering, coupling is the degree of interdependence between software modules; a measure of how closely connected two routines or modules are; the strength of the relationships between modules. Coupling is usually contrasted with cohesion. Low coupling often correlates with high cohesion, and vice versa. Low coupling is often thought to be a sign of a well-structured computer system and a good design, and when combined with high cohesion, supports the general goals of high readability and maintainability. History The software quality metrics of coupling and cohesion were invented by Larry Constantine in the late 1960s as part of a structured design, based on characteristics of “good” programming practices that reduced maintenance and modification costs. Structured design, including cohesion and coupling, were published in the article ''Stevens, Myers & Constantine'' (1974) and the book ''Yourdon & Constantine'' (1979), and the latter subsequently became stan ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Adaptive Reuse
Adaptive reuse refers to the process of reusing an existing building for a purpose other than which it was originally built or designed for. It is also known as recycling and conversion. Adaptive reuse is an effective strategy for optimizing the operational and commercial performance of built assets. Adaptive reuse of buildings can be an attractive alternative to new construction in terms of sustainability and a circular economy. It has prevented thousands of buildings' demolition and has allowed them to become critical components of urban regeneration. Not every old building can qualify for adaptive reuse. Architects, developers, builders and entrepreneurs who wish to become involved in rejuvenating and reconstructing a building must first make sure that the finished product will serve the need of the market, that it will be completely useful for its new purpose, and that it will be competitively priced. Definition Adaptive Reuse is defined as the aesthetic process that adapts bui ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Maintainability
In engineering, maintainability is the ease with which a product can be maintained to: * correct defects or their cause, * Repair or replace faulty or worn-out components without having to replace still working parts, * prevent unexpected working conditions, * maximize a product's useful life, * maximize efficiency, reliability, and safety, * meet new requirements, * make future maintenance easier, or * cope with a changing environment. In some cases, maintainability involves a system of continuous improvement - learning from the past to improve the ability to maintain systems, or improve the reliability of systems based on maintenance experience. In telecommunication and several other engineering fields, the term maintainability has the following meanings: * A characteristic of design and installation, expressed as the probability that an item will be retained in or restored to a specified condition within a given period of time, when the maintenance is performed by prescribed p ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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