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Loop-switch Sequence
A loop-switch sequence (also known as the for-case paradigm an Switched on Loops at The Daily WTF or Anti-) is a programming antipattern where a clear set of steps is implemented as a switch-within-a-loop. The loop-switch sequence is a specific derivative of |
The Daily WTF
The Daily WTF (also called Worse Than Failure from February to December 2007) is a humorous blog dedicated to "Curious Perversions in Information Technology". The blog, run by Alex Papadimoulis, "offers living examples of code that invites the exclamation ‘ WTF!?'" (What The Fuck!?) and "recounts tales of disastrous development, from project management gone spectacularly bad to inexplicable coding choices." In addition to horror stories, The Daily WTF "serve as repositor of knowledge and discussion forums for inquisitive web designers and developers" and has introduced several anti-patterns, including Softcoding, the Inner-Platform Effect, and IHBLRIA (Invented Here But Let's Reinvent It Anyway). The site also has an associated "Edition Française", a French-language edition headed up by Jocelyn Demoy, launched in March 2008, as well as a Polish edition. History The website was started on 17 May 2004, when Papadimoulis posted an entry entitled "Your Daily Cup of WTF" on hi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Duff's Device
In the C programming language, Duff's device is a way of manually implementing loop unrolling by interleaving two syntactic constructs of C: the - loop and a switch statement. Its discovery is credited to Tom Duff in November 1983, when Duff was working for Lucasfilm and used it to speed up a real-time animation program. Loop unrolling attempts to reduce the overhead of conditional branching needed to check whether a loop is done, by executing a batch of loop bodies per iteration. To handle cases where the number of iterations is not divisible by the unrolled-loop increments, a common technique among assembly language programmers is to jump directly into the middle of the unrolled loop body to handle the remainder. Duff implemented this technique in C by using C's case label fall-through feature to jump into the unrolled body. Original version Duff's problem was to copy 16-bit unsigned integers ("shorts" in most C implementations) from an array into a memory-mapped output regist ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Antipattern
An anti-pattern in software engineering, project management, and business processes is a common response to a recurring problem that is usually ineffective and risks being highly counterproductive. The term, coined in 1995 by computer programmer Andrew Koenig, was inspired by the book ''Design Patterns'' (which highlights a number of design patterns in software development that its authors considered to be highly reliable and effective) and first published in his article in the ''Journal of Object-Oriented Programming''. A further paper in 1996 presented by Michael Ackroyd at the Object World West Conference also documented anti-patterns. It was, however, the 1998 book ''AntiPatterns'' that both popularized the idea and extended its scope beyond the field of software design to include software architecture and project management. Other authors have extended it further since to encompass environmental, organizational, and cultural anti-patterns. Definition According to the authors ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Spaghetti Code
Spaghetti code is a pejorative phrase for difficult-to- maintain and unstructured computer source code. Code being developed with poor structure can be due to any of several factors, such as volatile project requirements, lack of programming style rules, and software engineers with insufficient ability or experience. Meaning Code that overuses GOTO statements rather than structured programming constructs, resulting in convoluted and unmaintainable programs, is often called spaghetti code. Such code has a complex and tangled control structure, resulting in a program flow that is conceptually like a bowl of spaghetti, twisted and tangled. In a 1980 publication by the United States National Bureau of Standards, the phrase ''spaghetti program'' was used to describe older programs having "fragmented and scattered files". Spaghetti code can also describe an anti-pattern in which object-oriented code is written in a procedural style, such as by creating classes whose methods are ov ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Switch Statement
In computer programming languages, a switch statement is a type of selection control mechanism used to allow the value of a variable or expression to change the control flow of program execution via search and map. Switch statements function somewhat similarly to the if statement used in programming languages like C/ C++, C#, Visual Basic .NET, Java and exist in most high-level imperative programming languages such as Pascal, Ada, C/ C++, C#, Visual Basic .NET, Java, and in many other types of language, using such keywords as switch, case, select, or inspect. Switch statements come in two main variants: a structured switch, as in Pascal, which takes exactly one branch, and an unstructured switch, as in C, which functions as a type of goto. The main reasons for using a switch include improving clarity, by reducing otherwise repetitive coding, and (if the heuristics permit) also offering the potential for faster execution through easier compiler optimization in many ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Inversion Of Control
In software engineering, inversion of control (IoC) is a design principle in which custom-written portions of a computer program receive the flow of control from an external source (e.g. a framework). The term "inversion" is historical: a software architecture with this design "inverts" control as compared to procedural programming. In procedural programming, a program's custom code calls reusable libraries to take care of generic tasks, but with inversion of control, it is the external code or framework that is in control and calls the custom code. Inversion of control has been widely used by application development frameworks since the rise of GUI environments and continues to be used both in GUI environments and in web server application frameworks. Inversion of control makes the framework extensible by the methods defined by the application programmer. Event-driven programming is often implemented using IoC so that the custom code need only be concerned with the handling ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Event-driven Programming
In computer programming, event-driven programming is a programming paradigm in which the Control flow, flow of the program is determined by external Event (computing), events. User interface, UI events from computer mouse, mice, computer keyboard, keyboards, touchpads and touchscreens, and external sensor inputs are common cases. Events may also be programmatically generated, such as from message passing, messages from other programs, notifications from other thread (computer science), threads, or other Computer network, network events. Event-driven programming is the dominant paradigm used in graphical user interfaces applications and network servers. In an event-driven application, there is generally an event loop that listens for events and then triggers a callback (computer programming), callback function when one of those events is detected. Event-driven programs can be written in any programming language, although the task is easier in languages that provide abstraction (co ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Event Loop
In computer science, the event loop (also known as message dispatcher, message loop, message pump, or run loop) is a programming construct or design pattern that waits for and dispatches events or messages in a program. The event loop works by making a request to some internal or external "event provider" (that generally blocks the request until an event has arrived), then calls the relevant event handler ("dispatches the event"). It is also commonly implemented in servers such as web servers. The event loop may be used in conjunction with a reactor, if the event provider follows the file interface, which can be selected or 'polled' (the Unix system call, not actual polling). The event loop almost always operates asynchronously with the message originator. When the event loop forms the central control flow construct of a program, as it often does, it may be termed the main loop or main event loop. This title is appropriate, because such an event loop is at the highest leve ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Event-driven Finite State Machine
In computation, a finite-state machine (FSM) is event driven if the transition from one state to another is triggered by an event or a message. This is in contrast to the parsing-theory origins of the term finite-state machine where the machine is described as consuming characters or tokens. Often these machines are implemented as threads or processes communicating with one another as part of a larger application. For example, a telecommunication protocol is most of the time implemented as an event-driven finite-state machine. Example in C This code describes the state machine for a very basic car radio system. It is basically an infinite loop that reads incoming events. The state machine is only 2 states: radio mode, or CD mode. The event is either a mode change from radio to cd back and forth, or a go to next (next preset for radio or next track for CD). /********************************************************************/ #include /************************************* ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Loop Unwinding
Loop unrolling, also known as loop unwinding, is a loop transformation technique that attempts to optimize a program's execution speed at the expense of its binary size, which is an approach known as space–time tradeoff. The transformation can be undertaken manually by the programmer or by an optimizing compiler. On modern processors, loop unrolling is often counterproductive, as the increased code size can cause more cache misses; ''cf.'' Duff's device. The goal of loop unwinding is to increase a program's speed by reducing or eliminating instructions that control the loop, such as pointer arithmetic and "end of loop" tests on each iteration; reducing branch penalties; as well as hiding latencies, including the delay in reading data from memory. To eliminate this computational overhead, loops can be re-written as a repeated sequence of similar independent statements. Loop unrolling is also part of certain formal verification techniques, in particular bounded model checking. A ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Observer Pattern
In software design and software engineering, the observer pattern is a software design pattern in which an object, called the ''subject'' (also known as ''event source'' or ''event stream''), maintains a list of its dependents, called observers (also known as ''event sinks''), and automatically notifies them of any state (computer science), state changes, typically by calling one of their method (computer science), methods. The subject knows its observers through a standardized interface and manages the subscription list directly. This pattern creates a one-to-many dependency where multiple observers can listen to a single subject, but the coupling is typically synchronous and direct—the subject calls observer methods when changes occur, though asynchronous implementations using event queues are possible. Unlike the publish-subscribe pattern, there is no intermediary broker; the subject and observers have direct references to each other. It is commonly used to implement event ha ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
