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Hooking
In computer programming, the term hooking covers a range of techniques used to alter or augment the behaviour of an operating system, of applications, or of other software components by intercepting function calls or messages or events passed between software components. Code that handles such intercepted function calls, events or messages is called a hook. Hook methods are of particular importance in the template method pattern where common code in an abstract class can be augmented by custom code in a subclass. In this case each hook method is defined in the abstract class with an empty implementation which then allows a different implementation to be supplied in each concrete subclass. Hooking is used for many purposes, including debugging and extending functionality. Examples might include intercepting keyboard or mouse event messages before they reach an application, or intercepting operating system calls in order to monitor behavior or modify the function of an applicat ... [...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] |
Computer Programming
Computer programming or coding is the composition of sequences of instructions, called computer program, programs, that computers can follow to perform tasks. It involves designing and implementing algorithms, step-by-step specifications of procedures, by writing source code, code in one or more programming languages. Programmers typically use high-level programming languages that are more easily intelligible to humans than machine code, which is directly executed by the central processing unit. Proficient programming usually requires expertise in several different subjects, including knowledge of the Domain (software engineering), application domain, details of programming languages and generic code library (computing), libraries, specialized algorithms, and Logic#Formal logic, formal logic. Auxiliary tasks accompanying and related to programming include Requirements analysis, analyzing requirements, Software testing, testing, debugging (investigating and fixing problems), imple ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Function (computer Science)
In computer programming, a function (also procedure, method, subroutine, routine, or subprogram) is a callable unit of software logic that has a well-defined interface and behavior and can be invoked multiple times. Callable units provide a powerful programming tool. The primary purpose is to allow for the decomposition of a large and/or complicated problem into chunks that have relatively low cognitive load and to assign the chunks meaningful names (unless they are anonymous). Judicious application can reduce the cost of developing and maintaining software, while increasing its quality and reliability. Callable units are present at multiple levels of abstraction in the programming environment. For example, a programmer may write a function in source code that is compiled to machine code that implements similar semantics. There is a callable unit in the source code and an associated one in the machine code, but they are different kinds of callable units with different impl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Interrupt Vector
An interrupt vector table (IVT) is a data structure that associates a list of interrupt handlers with a list of interrupt requests in a table of interrupt vectors. Each entry of the interrupt vector table, called an interrupt vector, is the address of an interrupt handler (also known as Interrupt_handler, ISR). While the concept is common across processor architectures, IVTs may be implemented in architecture-specific fashions. For example, a dispatch table is one method of implementing an interrupt vector table. Background Most processors have an interrupt vector table, including chips from Intel, AMD, Infineon Technologies, Infineon, Microchip AVR microcontrollers, Atmel, NXP, ARM architecture, ARM, etc. Interrupt handlers Handling methods An interrupt vector table is used in the three most popular methods of finding the starting address of the interrupt service routine: "Predefined" The "predefined" method loads the program counter (PC) directly with the address of some ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Shared Library
In computing, a library is a collection of System resource, resources that can be leveraged during software development to implement a computer program. Commonly, a library consists of executable code such as compiled function (computer science), functions and Class (computer programming), classes, or a library can be a collection of source code. A resource library may contain data such as images and Text string, text. A library can be used by multiple, independent consumers (programs and other libraries). This differs from resources defined in a program which can usually only be used by that program. When a consumer uses a library resource, it gains the value of the library without having to implement it itself. Libraries encourage software reuse in a Modular programming, modular fashion. Libraries can use other libraries resulting in a hierarchy of libraries in a program. When writing code that uses a library, a programmer only needs to know how to use it not its internal d ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Kernel (operating System)
A kernel is a computer program at the core of a computer's operating system that always has complete control over everything in the system. The kernel is also responsible for preventing and mitigating conflicts between different processes. It is the portion of the operating system code that is always resident in memory and facilitates interactions between hardware and software components. A full kernel controls all hardware resources (e.g. I/O, memory, cryptography) via device drivers, arbitrates conflicts between processes concerning such resources, and optimizes the use of common resources, such as CPU, cache, file systems, and network sockets. On most systems, the kernel is one of the first programs loaded on startup (after the bootloader). It handles the rest of startup as well as memory, peripherals, and input/output (I/O) requests from software, translating them into data-processing instructions for the central processing unit. The critical code of the kernel is usua ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mouse (computing)
A computer mouse (plural mice; also mouses) is a hand-held pointing device that detects Plane (mathematics), two-dimensional motion relative to a surface. This motion is typically translated into the motion of the Cursor (user interface)#Pointer, pointer (called a cursor) on a computer monitor, display, which allows a smooth control of the graphical user interface of a computer. The first public demonstration of a mouse controlling a computer system was done by Doug Engelbart in 1968 as part of the Mother of All Demos. Mice originally used two separate wheels to directly track movement across a surface: one in the x-dimension and one in the Y. Later, the standard design shifted to use a ball rolling on a surface to detect motion, in turn connected to internal rollers. Most modern mice use optical mouse, optical movement detection with no moving parts. Though originally all mice were connected to a computer by a cable, many modern mice are cordless, relying on short-range rad ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Keyboard (computing)
A computer keyboard is a built-in or peripheral input device modeled after the typewriter keyboard which uses an arrangement of buttons or Push-button, keys to act as Mechanical keyboard, mechanical levers or Electronic switching system, electronic switches. Replacing early punched cards and paper tape technology, interaction via teleprinter-style keyboards have been the main input device, input method for computers since the 1970s, supplemented by the computer mouse since the 1980s, and the touchscreen since the 2000s. Keyboard keys (buttons) typically have a set of characters Engraving, engraved or Printing, printed on them, and each press of a key typically corresponds to a single written symbol. However, producing some symbols may require pressing and holding several keys simultaneously or in sequence. While most keys produce character (computing), characters (Letter (alphabet), letters, Numerical digit, numbers or symbols), other keys (such as the escape key) can prompt the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Menu (computing)
In user interface design, a menu is a list of options presented to the user. Navigation A user chooses an option from a menu by using an input device. Some input methods require linear navigation: the user must move a cursor or otherwise pass from one menu item to another until reaching the selection. On a computer terminal, a reverse video bar may serve as the cursor. Touch user interfaces and menus that accept codes to select menu options without navigation are two examples of non-linear interfaces. Some of the input devices used in menu interfaces are touchscreens, keyboards, mice, remote controls, and microphones. In a voice-activated system, such as interactive voice response, a microphone sends a recording of the user's voice to a speech recognition system, which translates it to a command. Types of menus A computer using a command line interface may present a list of relevant commands with assigned short-cuts (digits, numbers or characters) on the screen. Ent ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Scrollbar
A scrollbar is an interaction technique or widget (GUI), widget in which continuous text, pictures, or any other content can be Scrolling, scrolled in a predetermined direction (up, down, left, or right) on a computer display, window (computing), window, or viewport so that all of the content can be viewed, even if only a fraction of the content can be seen on a device's screen at one time. It offers a solution to the problem of Web navigation, navigation to a known or unknown location within a two-dimensional information space. It was also known as a handle in the very first GUIs. They are present in a wide range of electronic devices including computers, graphing calculators, mobile phones, and portable media players. The user interacts with the scrollbar elements using some method of direct action, the scrollbar translates that action into scrolling commands, and the user receives feedback through a visual updating of both the scrollbar elements and the scrolled content. Altho ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dialog Box
In computing, a dialog box (also simply dialog) is a graphical control element in the form of a small window that communicates information to the user and prompts them for a response. Dialog boxes are classified as " modal" or "modeless", depending on whether they block interaction with the software that initiated the dialog. The type of dialog box displayed is dependent upon the desired user interaction. The simplest type of dialog box is the alert, which displays a message and may require an acknowledgment that the message has been read, usually by clicking "OK", or a decision as to whether or not an action should proceed, by clicking "OK" or "Cancel". Alerts are also used to display a "termination notice"—sometimes requesting confirmation that the notice has been read—in the event of either an intentional closing or unintentional closing (" crash") of an application or the operating system. ( E.g., " Gedit has encountered an error and must close.") Although t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
