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Meta-object System
Meta Object System is a part of Qt framework core provided to support Qt extensions to C++ like signals/slots for inter-object communication, run-time type information, and the dynamic property system. Architecture The Meta object system consists of 3 things: QObject class, Q_OBJECT macro and a tool called moc (Meta-Object Compiler). QObject is the base class for all Qt classes, Q_OBJECT macro is used to enable meta-object features in classes and finally moc is a preprocessor that changes Q_OBJECT macro instances to C++ source code In computing, source code, or simply code or source, is a plain text computer program written in a programming language. A programmer writes the human readable source code to control the behavior of a computer. Since a computer, at base, only ... to enable meta object system mechanism in the class in which it is used. Using the meta object system has brought some criticism. In Qt documentation, several reasons have been given for the use o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
Qt (framework)
Qt ( pronounced "cute") is a cross-platform application development framework for creating graphical user interfaces as well as Cross-platform software, cross-platform applications that run on various software and hardware platforms such as Linux, Windows, macOS, Android (operating system), Android or embedded systems with little or no change in the underlying codebase while still being a native application with native capabilities and speed. Qt is currently being developed by The Qt Company, a publicly listed company, and the Qt Project under open-source governance, involving individual developers and organizations working to advance Qt. Qt is available under both commercial licenses and open-source GNU General Public License, GPL 2.0, GPL 3.0, and GNU Lesser General Public License, LGPL 3.0 licenses. Purposes and abilities Qt is used for developing graphical user interfaces (GUIs) and multi-platform application software, applications that run on all major Desktop computer ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
Signals And Slots
Signals and slots is a language construct introduced in Qt for communication between objects which makes it easy to implement the observer pattern while avoiding boilerplate code. The concept is that GUI widgets, and other objects, can send signals containing event information which can be received by other objects using special member functions known as slots. This is similar to C/C++ function pointers, but the signal/slot system ensures the type-correctness of callback arguments. The signal/slot system fits well with the way graphical user interfaces are designed. Similarly, the signal/slot system can be used for other non-GUI usages, for example asynchronous I/O (including sockets, pipes, serial devices, etc.) event notification or to associate timeout events with appropriate object instances and methods or functions. It is easy to use and no registration/deregistration/invocation code need to be written, because Qt's metaobject compiler (MOC) automatically generates the neede ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
Type System
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 synta ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
Class (computer Programming)
In object-oriented programming, a class defines the shared aspects of objects created from the class. The capabilities of a class differ between programming languages, but generally the shared aspects consist of state ( variables) and behavior ( methods) that are each either associated with a particular object or with all objects of that class. Object state can differ between each instance of the class whereas the class state is shared by all of them. The object methods include access to the object state (via an implicit or explicit parameter that references the object) whereas class methods do not. If the language supports inheritance, a class can be defined based on another class with all of its state and behavior plus additional state and behavior that further specializes the class. The specialized class is a ''sub-class'', and the class it is based on is its ''superclass''. Attributes Object lifecycle As an instance of a class, an object is constructed from a class via '' ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
Macro (computer Science)
In computer programming, a macro (short for "macro instruction"; ) is a rule or pattern that specifies how a certain input should be mapped to a replacement output. Applying a macro to an input is known as macro expansion. The input and output may be a sequence of lexical tokens or characters, or a syntax tree. Character macros are supported in software applications to make it easy to invoke common command sequences. Token and tree macros are supported in some programming languages to enable code reuse or to extend the language, sometimes for domain-specific languages. Macros are used to make a sequence of computing instructions available to the programmer as a single program statement, making the programming task less tedious and less error-prone. Thus, they are called "macros" because a "big" block of code can be expanded from a "small" sequence of characters. Macros often allow positional or keyword parameters that dictate what the conditional assembler program gen ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
Compiler
In computing, a compiler is a computer program that Translator (computing), translates computer code written in one programming language (the ''source'' language) into another language (the ''target'' language). The name "compiler" is primarily used for programs that translate source code from a high-level programming language to a lower level language, low-level programming language (e.g. assembly language, object code, or machine code) to create an executable program.Compilers: Principles, Techniques, and Tools by Alfred V. Aho, Ravi Sethi, Jeffrey D. Ullman - Second Edition, 2007 There are many different types of compilers which produce output in different useful forms. A ''cross-compiler'' produces code for a different Central processing unit, CPU or operating system than the one on which the cross-compiler itself runs. A ''bootstrap compiler'' is often a temporary compiler, used for compiling a more permanent or better optimised compiler for a language. Related software ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
Preprocessor
In computer science, a preprocessor (or precompiler) is a Computer program, program that processes its input data to produce output that is used as input in another program. The output is said to be a preprocessed form of the input data, which is often used by some subsequent programs like compilers. The amount and kind of processing done depends on the nature of the preprocessor; some preprocessors are only capable of performing relatively simple textual substitutions and Macro (computer science), macro expansions, while others have the power of full-fledged programming languages. A common example from computer programming is the processing performed on source code before the next step of compilation. In some computer languages (e.g., C (programming language), C and PL/I (programming language), PL/I) there is a phase of compiler, translation known as ''preprocessing''. It can also include macro processing, file inclusion and language extensions. Lexical preprocessors Lexical pr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
Source Code
In computing, source code, or simply code or source, is a plain text computer program written in a programming language. A programmer writes the human readable source code to control the behavior of a computer. Since a computer, at base, only understands machine code, source code must be Translator (computing), translated before a computer can Execution (computing), execute it. The translation process can be implemented three ways. Source code can be converted into machine code by a compiler or an assembler (computing), assembler. The resulting executable is machine code ready for the computer. Alternatively, source code can be executed without conversion via an interpreter (computing), interpreter. An interpreter loads the source code into memory. It simultaneously translates and executes each statement (computer science), statement. A method that combines compilation and interpretation is to first produce bytecode. Bytecode is an intermediate representation of source code tha ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
Code Generation (compiler)
tuo.maxnam computing, code generation is part of the process chain of a compiler, in which an intermediate representation of source code is converted into a form (e.g., machine code) that can be readily executed by the target system. Sophisticated compilers typically perform multiple passes over various intermediate forms. This multi-stage process is used because many algorithms for code optimization are easier to apply one at a time, or because the input to one optimization relies on the completed processing performed by another optimization. This organization also facilitates the creation of a single compiler that can target multiple architectures, as only the last of the code generation stages (the ''backend'') needs to change from target to target. (For more information on compiler design, see Compiler.) The input to the code generator typically consists of a parse tree or an abstract syntax tree. The tree is converted into a linear sequence of instructions, usually in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
