文档介绍：1. Introduction To Objects The progress of abstraction All programming languages provide abstractions. It can be argued that plexity of the problems you ’ re able to solve is directly related to the kind and quality of abstraction. By “ kind ”I mean, “ What is it that you are abstracting? ” Assembly language isa small abstraction of the underlying machine. Many so-called “ imperative ” languages that followed (such as FORTRAN, BASIC, and C) were abstractions of assembly language. These languages are big improvements over assembly language, but their primary abstraction still requires you to think in terms of the structure of puter rather than the structure of the problem you are trying to solve. The programmer must establish the association between the machine model (in the “ solution space, ” which is the place where you ’ re modeling that problem, such puter) and the model of the problem that is actually being solved (in the “ problem space, ” which is the place where the problem exists). The effort required to perform this mapping, and the fact that it is extrinsic to the programming language, produces programs that are difficult to write and expensive to maintain, and asa side effect created the entire “ programming methods ” industry. The alternative to modeling the machine is to model the problem you ’ re trying to solve. Early languages such as LISP and APL chose par