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Abstract machines are "machines" because they allow step-by-step execution of programs; they are "abstract" because they ignore many aspects of actual machines. [3] A typical abstract machine consists of a definition in terms of input, output, and the set of allowable operations used to turn the former into the latter.
A hardware abstraction layer (HAL) is an abstraction layer, implemented in software, between the physical hardware of a computer and the software that runs on that computer. . Its function is to hide differences in hardware from most of the operating system kernel, so that most of the kernel-mode code does not need to be changed to run on systems with different hardwa
Abstract data type for an abstract description of a set of data; Algorithm for an abstract description of a computational procedure; Bracket abstraction for making a term into a function of a variable; Data modeling for structuring data independent of the processes that use it; Encapsulation for abstractions that hide implementation details
[26] [27] In C++, an abstract class is a class having at least one abstract method given by the appropriate syntax in that language (a pure virtual function in C++ parlance). [25] A class consisting of only pure virtual methods is called a pure abstract base class (or pure ABC) in C++ and is also known as an interface by users of the language. [13]
The bridge pattern is useful when both the class and what it does vary often. The class itself can be thought of as the abstraction and what the class can do as the implementation. The bridge pattern can also be thought of as two layers of abstraction. When there is only one fixed implementation, this pattern is known as the Pimpl idiom in the ...
C compilers do not name mangle symbols in the way that C++ compilers do. [20] Depending on the compiler and architecture, it also may be the case that calling conventions differ between the two languages. For these reasons, for C++ code to call a C function foo(), the C++ code must prototype foo() with extern "C".
The C++ examples in this section demonstrate the principle of using composition and interfaces to achieve code reuse and polymorphism. Due to the C++ language not having a dedicated keyword to declare interfaces, the following C++ example uses inheritance from a pure abstract base class .
In 1983, David H. D. Warren designed an abstract machine for the execution of Prolog consisting of a memory architecture and an instruction set. [1] [2] [3] This design became known as the Warren Abstract Machine (WAM) and has become the de facto standard target for Prolog compilers.