创建可复用软件的接口与实现技术

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"C Interfaces and Implementations - Techniques for Creating Reusable Software" 本书主要探讨了如何使用C语言创建可重用的软件，通过清晰的接口设计和高效的实现策略来提升代码的复用性和质量。作者在书中详细阐述了以下几个关键知识点： 1. **Literate Programs** (第1章1.1节) literate programming是一种编程哲学，强调将程序编写成既可读性强又可以编译的文档。这种方法鼓励程序员将代码与解释性文字交织在一起，使得代码更易于理解和维护。 2. **Programming Style** (第1章1.2节) 编程风格对于代码的可读性和可维护性至关重要。书中讨论了良好的命名规范、代码布局、注释和文档化的重要性，以及如何遵循这些原则来提高代码质量。 3. **Efficiency** (第1章1.3节和第2章2.5节) 效率是C语言开发中的重要考虑因素，书中探讨了如何在不影响可读性的前提下优化代码性能，包括算法选择、内存管理和数据结构的设计。 4. **Interfaces and Implementations** (第2章) 接口和实现是软件设计的核心概念。接口定义了用户如何与代码交互，而实现则处理内部工作细节。书中详细介绍了如何设计清晰、稳定的接口，并提供了实现高效、可靠代码的方法。 5. **Abstract Data Types (ADTs)** (第2章2.4节) ADTs是通过接口隐藏数据结构的具体实现，提供了一种抽象的方式来处理数据。书中的讨论涵盖了如何设计和使用ADTs来增强代码的模块性和可重用性。 6. **Client Responsibilities** (第2章2.5节) 客户端（调用者）的责任是指正确地使用接口。书中强调了客户端必须遵守接口规定，以确保软件的稳定性和可靠性。 7. **Atoms** (第3章) Atoms是不可分割的基本数据单元，常用于并发编程中。本章介绍了如何设计和实现原子操作的接口和内部机制，以保证并发环境下的数据一致性。 8. **Exceptions and Assertions** (第4章) 异常处理和断言是错误检测和恢复的重要工具。书中讨论了如何通过异常接口处理运行时错误，以及如何利用断言来确保代码的正确性。 9. **Memory Management** (第5章和第6章) 内存管理是C编程中的关键挑战。书中详细讲解了内存分配、释放的接口设计，以及生产环境和检查环境下的实现策略，如内存泄漏检测和防止。 10. **More Memory Management** (第6章) 进一步讨论了高级内存管理技术，可能包括动态内存池、垃圾回收等，以提高内存使用的效率和安全性。每一章都包含进一步阅读的建议和练习题，帮助读者巩固理解并应用所学知识。通过学习本书，读者将能够掌握创建高效、可重用C软件的关键技术和实践。

INTRODUCTION

big program is made up of many small modules. These modules

provide the functions, procedures, and data structures used in

the program. Ideally, most of these modules are ready-made and

come from libraries; only those that are specific to the application at

hand need to be written from scratch. Assuming that library code has

been tested thoroughly, only the application-specific code will contain

bugs, and debugging can be confined to just that code.

Unfortunately, this theoretical ideal rarely occurs in practice. Most

programs are written from scratch, and they use libraries only for the

lowest level facilities, such as I/O and memory management. Program-

mers often write application-specific code for even these kinds of low-

level components; it’s common, for example, to find applications in

which the C library functions malloc and free have been replaced by

custom memory-management functions.

There are undoubtedly many reasons for this situation; one of them is

that widely available libraries of robust, well designed modules are rare.

Some of the libraries that are available are mediocre and lack standards.

The C library has been standardized since 1989, and is only now appear-

ing on most platforms.

Another reason is size: Some libraries are so big that mastering them

is a major undertaking. If this effort even appears to be close to the

effort required to write the application, programmers may simply reim-

plement the parts of the library they need. User-interface libraries, which

have proliferated recently, often exhibit this problem.

Library design and implementation are difficult. Designers must tread

carefully between generality, simplicity, and efficiency. If the routines

and data structures in a library are too general, they may be too hard to

C Interfaces and Implementations: Techniques for Creating Reusable Software. C Interfaces and Implementations: Techniques for Creating Reusable Software, ISBN: 9780321562807

Prepared for frliu@microsoft.com, Frank Liu

2 INTRODUCTION

use or inefficient for their intended purposes. If they’re too simple, they

run the risk of not satisfying the demands of applications that might use

them. If they’re too confusing, programmers won’t use them. The C

library itself provides a few examples; its realloc function, for instance,

is a marvel of confusion.

Library implementors face similar hurdles. Even if the design is done

well, a poor implementation will scare off users. If an implementation is

too slow or too big — or just perceived to be so — programmers will

design their own replacements. Worst of all, if an implementation has

bugs, it shatters the ideal outlined above and renders the library useless.

This book describes the design and implementation of a library that is

suitable for a wide range of applications written in the C programming

language. The library exports a set of modules that provide functions

and data structures for “programming-in-the-small.” These modules are

suitable for use as “piece parts” in applications or application compo-

nents that are a few thousand lines long.

Most of the facilities described in the subsequent chapters are those

covered in undergraduate courses on data structures and algorithms. But

here, more attention is paid to how they are packaged and to making

them robust. Each module is presented as an interface and its implemen-

tation. This design methodology, explained in Chapter 2, separates mod-

ule specifications from their implementations, promotes clarity and

precision in those specifications, and helps provide robust imple-

mentations.

1.1 Literate Programs

This book describes modules not by prescription, but by example. Each

chapter describes one or two interfaces and their implementations in

full. These descriptions are presented as literate programs. The code for

an interface and its implementation is intertwined with prose that

explains it. More important, each chapter is the source code for the inter-

faces and implementations it describes. The code is extracted automati-

cally from the source text for this book; what you see is what you get.

A literate program is composed of English prose and labeled chunks of

program code. For example,

¢compute x • y²≡

sum = 0;

C Interfaces and Implementations: Techniques for Creating Reusable Software. C Interfaces and Implementations: Techniques for Creating Reusable Software, ISBN: 9780321562807

Prepared for frliu@microsoft.com, Frank Liu