提升PHP应用的性能与特性：函数式编程策略

需积分: 10 135 浏览量更新于2024-07-19 收藏 2.84MB PDF 举报

"Pro Functional PHP Programming" 是一本由 Rob Aley 编著的专业书籍，它旨在帮助开发者将函数式编程的强大功能融入PHP应用程序中，从而实现性能优化、并发处理、提高测试性以及代码简洁性等多方面的优势。本书主要关注的是在PHP应用开发策略中如何有效地应用函数式编程原则，以提升软件的效能。该书详细探讨了以下几个关键主题： 1. **性能优化**：通过函数式编程方法，作者会介绍如何通过减少冗余计算、利用纯函数（Pure Functions）和无状态设计来改进程序的执行效率。这些技巧有助于降低内存消耗，减少不必要的I/O操作，从而提升应用程序的整体性能。 2. **并发处理**：函数式编程强调数据流和无共享状态，这对于处理并发任务非常有利。书中可能会涵盖并行计算、惰性求值（Lazy Evaluation）以及高阶函数的使用，帮助开发者编写能够更好地利用现代多核处理器的高效并发代码。 3. **测试性**：由于函数式编程通常具有可预测性和不变性，它提供了更好的测试基础。书中可能介绍了如何通过TDD（Test-Driven Development）和断言函数等技术来确保代码的正确性，并简化了测试复杂性的管理。 4. **代码简洁性**：函数式编程强调代码的简洁和一致性，通过避免副作用和循环依赖，使得代码更易于理解和维护。书中可能会展示如何通过组合和映射等函数式编程特性来编写更加简洁、优雅的代码。此外，"Pro Functional PHP Programming" 提供了丰富的实战案例和理论分析，使读者能够掌握如何将这些概念实际应用到PHP项目中。同时，书籍还附带了ISBN-13数字标识和版权信息，确保了内容的权威性和合法性。无论你是经验丰富的开发者还是初学者，这本书都将是你提升PHP编程技能，特别是向函数式编程转型的重要参考资料。

About the Technical Reviewer

Christopher Pitt is a developer and writer, working at SilverStripe. He usually works on application

architecture, though sometimes you’ll find him building compilers or robots. He is also the author of several

web development books and is a contributor on various open source projects like AdonisJs.

xvii

R. Aley, Pro Functional PHP Programming, DOI 10.1007/978-1-4842-2958-3_1

CHAPTER 1

Introduction

Functional programming isn’t something that is often associated with PHP. Yet for quite a while PHP has had

all the features necessary to create software using the functional paradigm. In this book, you’ll take a look

at what functional programming is, how to do it in PHP, and the different ways in which you can use it to

improve your PHP software.

Who Is This Book For?

This book isn’t an introduction to PHP itself; it assumes you have some basic (or, indeed, advanced)

experience in PHP scripting. You don’t need to be an expert to follow along; I’ll cover all the key concepts

in PHP you’ll need to know to be able to implement functional designs in your code and point you in the

direction of resources such as web sites and other books that you can use to learn or investigate any related

concepts that I don’t cover directly.

Absolute PHP beginners aside, this book is suitable for all programmers. Whether you have a pressing

need to learn functional programming (perhaps you’ve taken over a functional PHP code base) or you are

just interested in finding out what the “buzz” around functional programming is all about, there is something

in this book for you. There’s even likely to be something for those skeptical about creating software using the

functional programming paradigm. I think that most programmers will find useful lessons and code patterns

to take away from the functional programming style that will enhance their object-oriented or procedural

programming work. If all else fails, knowledge of functional programming looks good on your résumé!

What Is Functional Programming?

Functional programming is a declarative programming paradigm that abstracts code into

pure, immutable, side-effect-free functions, allowing the programmer to compose such

functions together to make programs that are easy to reason about.

That is my definition of functional programming. Ask five other functional programmers to define functional

programming and you’ll get four more answers (two just copied the same answer from Wikipedia). There’s

no “standard” definition; different people and different programming languages implement functional

programming elements differently. These differences are partly because of the practicalities of the language

in question and sometimes because of the target platforms, data, and usage scenarios, but often they come

down to what I call “programming religion”: a fixed, sometimes irrational, but often deeply held belief of

how a particular paradigm should be. Even within the small community of PHP functional programmers,

you won’t find an exact consensus. In PHP, functional programming is not a core concept, but even in

languages where it is (e.g., Lisp, Scala, etc.), there are many “related” understandings of what constitutes true

functional programming. While that may sound problematic, you’ll still “know it when you see it,” and when

it gets woolly around the edges, you can choose to define it in any way you see fit!

Chapter 1 ■ IntroduCtIon

PHP isn’t a pure functional programming language, but you can still use it for functional programming

(which is good; otherwise this book wouldn’t be very long). A few elements of what some purists consider to

be essential functional programming concepts are harder to implement with PHP’s standard syntax, so it’s

perhaps slightly more accurate to say that you can program in a functional programming “style” in PHP.

Let’s now look a little more in depth at what functional programming actually is in practice. Functional

programming is a “declarative” style of programming, which means you specify what you want it to do rather

than how you want to do it. It’s a higher level of abstraction than you may be used to with OO or procedural

programming. However, you almost certainly use declarative programming on a day-to-day basis when using

SQL, HTML, regular expressions, and similar languages. Consider the SQL snippet shown in Listing 1-1.

Listing 1-1. declarative.sql

SELECT forename,

Surname

FROM users

WHERE username = 'rob'

AND password = 'password1';

This is telling your database server what you want it to do (select the real name based on super-secret

security credentials), but you don’t tell it how to do it. You don’t tell it the following:

• Where to look on disk for the data

• How to parse or search the data for matching records

• How to determine whether a record matches your criteria

• How to extract the relevant fields from the record

And so on. You simply tell it what you want it to achieve for you.

Now obviously, at some point, you need to tell the computer how to do something. With the SQL example

in Listing 1-1, you do that by getting some rather clever people to write database management software

(DBMS) for you. In functional programming, you’ll tend to need to write the implementation code yourself,

but to make it a manageable task, you break that down into the smallest possible chunks and then use a

hierarchical chain of declarative function calls to tell the computer what to do with that code. If you use the

Composer dependency management system, you will already be using a similar paradigm: there are many

libraries of code available that abstract away the tasks that you need to do; you simply “compose” a list of

libraries together to do what you want. In functional programming, you do exactly the same; you take functions

that do something (like the libraries Composer provides) and compose them together into a program.

Having a program that is essentially a list of what you want to achieve sounds very good on paper,

and indeed it makes it easy to understand and reason about your program. To make the idea a little more

concrete, let’s take a look at a small functional-style program (Listing 1-2).

Listing 1-2. example.php

<?php

require_once('image_functions.php');

require_once('stats_functions.php');

剩余300页未读，继续阅读

Teocci

粉丝: 1
资源: 19

提升PHP应用的性能与特性：函数式编程策略

Functional PHP

Pro Functional PHP Programming epub

Programming PHP

Pro Functional PHP Programming azw3

functional-programming

Functional-programming

Functional-Programming

Functional_Programming

Functional Python Programming

functional-programming-php:使用php实现函数式编程方法

最新资源