292 lines
29 KiB
HTML
292 lines
29 KiB
HTML
|
<!DOCTYPE HTML>
|
|||
|
|
<html lang="en" class="sidebar-visible no-js light">
|
|||
|
|
<head>
|
|||
|
|
<!-- Book generated using mdBook -->
|
|||
|
|
<meta charset="UTF-8">
|
|||
|
|
<title>Separating Modules into Different Files - The Rust Programming Language</title>
|
|||
|
|
|
|||
|
|
|
|||
|
|
<meta content="text/html; charset=utf-8" http-equiv="Content-Type">
|
|||
|
|
<meta name="description" content="">
|
|||
|
|
<meta name="viewport" content="width=device-width, initial-scale=1">
|
|||
|
|
<meta name="theme-color" content="#ffffff" />
|
|||
|
|
|
|||
|
|
<link rel="shortcut icon" href="favicon.png">
|
|||
|
|
<link rel="stylesheet" href="css/variables.css">
|
|||
|
|
<link rel="stylesheet" href="css/general.css">
|
|||
|
|
<link rel="stylesheet" href="css/chrome.css">
|
|||
|
|
<link rel="stylesheet" href="css/print.css" media="print">
|
|||
|
|
|
|||
|
|
<!-- Fonts -->
|
|||
|
|
<link rel="stylesheet" href="FontAwesome/css/font-awesome.css">
|
|||
|
|
<link href="googleFonts/css.css" rel="stylesheet" type="text/css">
|
|||
|
|
|
|||
|
|
<!-- Highlight.js Stylesheets -->
|
|||
|
|
<link rel="stylesheet" href="highlight.css">
|
|||
|
|
<link rel="stylesheet" href="tomorrow-night.css">
|
|||
|
|
<link rel="stylesheet" href="ayu-highlight.css">
|
|||
|
|
|
|||
|
|
<!-- Custom theme stylesheets -->
|
|||
|
|
|
|||
|
|
<link rel="stylesheet" href="ferris.css">
|
|||
|
|
|
|||
|
|
<link rel="stylesheet" href="theme/2018-edition.css">
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
</head>
|
|||
|
|
<body>
|
|||
|
|
<!-- Provide site root to javascript -->
|
|||
|
|
<script type="text/javascript">
|
|||
|
|
var path_to_root = "";
|
|||
|
|
var default_theme = window.matchMedia("(prefers-color-scheme: dark)").matches ? "light" : "light";
|
|||
|
|
</script>
|
|||
|
|
|
|||
|
|
<!-- Work around some values being stored in localStorage wrapped in quotes -->
|
|||
|
|
<script type="text/javascript">
|
|||
|
|
try {
|
|||
|
|
var theme = localStorage.getItem('mdbook-theme');
|
|||
|
|
var sidebar = localStorage.getItem('mdbook-sidebar');
|
|||
|
|
|
|||
|
|
if (theme.startsWith('"') && theme.endsWith('"')) {
|
|||
|
|
localStorage.setItem('mdbook-theme', theme.slice(1, theme.length - 1));
|
|||
|
|
}
|
|||
|
|
|
|||
|
|
if (sidebar.startsWith('"') && sidebar.endsWith('"')) {
|
|||
|
|
localStorage.setItem('mdbook-sidebar', sidebar.slice(1, sidebar.length - 1));
|
|||
|
|
}
|
|||
|
|
} catch (e) { }
|
|||
|
|
</script>
|
|||
|
|
|
|||
|
|
<!-- Set the theme before any content is loaded, prevents flash -->
|
|||
|
|
<script type="text/javascript">
|
|||
|
|
var theme;
|
|||
|
|
try { theme = localStorage.getItem('mdbook-theme'); } catch(e) { }
|
|||
|
|
if (theme === null || theme === undefined) { theme = default_theme; }
|
|||
|
|
var html = document.querySelector('html');
|
|||
|
|
html.classList.remove('no-js')
|
|||
|
|
html.classList.remove('light')
|
|||
|
|
html.classList.add(theme);
|
|||
|
|
html.classList.add('js');
|
|||
|
|
</script>
|
|||
|
|
|
|||
|
|
<!-- Hide / unhide sidebar before it is displayed -->
|
|||
|
|
<script type="text/javascript">
|
|||
|
|
var html = document.querySelector('html');
|
|||
|
|
var sidebar = 'hidden';
|
|||
|
|
if (document.body.clientWidth >= 1080) {
|
|||
|
|
try { sidebar = localStorage.getItem('mdbook-sidebar'); } catch(e) { }
|
|||
|
|
sidebar = sidebar || 'visible';
|
|||
|
|
}
|
|||
|
|
html.classList.remove('sidebar-visible');
|
|||
|
|
html.classList.add("sidebar-" + sidebar);
|
|||
|
|
</script>
|
|||
|
|
|
|||
|
|
<nav id="sidebar" class="sidebar" aria-label="Table of contents">
|
|||
|
|
<div id="sidebar-scrollbox" class="sidebar-scrollbox">
|
|||
|
|
<ol class="chapter"><li class="expanded affix "><a href="title-page.html">The Rust Programming Language</a></li><li class="expanded affix "><a href="foreword.html">Foreword</a></li><li class="expanded affix "><a href="ch00-00-introduction.html">Introduction</a></li><li class="expanded "><a href="ch01-00-getting-started.html"><strong aria-hidden="true">1.</strong> Getting Started</a></li><li><ol class="section"><li class="expanded "><a href="ch01-01-installation.html"><strong aria-hidden="true">1.1.</strong> Installation</a></li><li class="expanded "><a href="ch01-02-hello-world.html"><strong aria-hidden="true">1.2.</strong> Hello, World!</a></li><li class="expanded "><a href="ch01-03-hello-cargo.html"><strong aria-hidden="true">1.3.</strong> Hello, Cargo!</a></li></ol></li><li class="expanded "><a href="ch02-00-guessing-game-tutorial.html"><strong aria-hidden="true">2.</strong> Programming a Guessing Game</a></li><li class="expanded "><a href="ch03-00-common-programming-concepts.html"><strong aria-hidden="true">3.</strong> Common Programming Concepts</a></li><li><ol class="section"><li class="expanded "><a href="ch03-01-variables-and-mutability.html"><strong aria-hidden="true">3.1.</strong> Variables and Mutability</a></li><li class="expanded "><a href="ch03-02-data-types.html"><strong aria-hidden="true">3.2.</strong> Data Types</a></li><li class="expanded "><a href="ch03-03-how-functions-work.html"><strong aria-hidden="true">3.3.</strong> Functions</a></li><li class="expanded "><a href="ch03-04-comments.html"><strong aria-hidden="true">3.4.</strong> Comments</a></li><li class="expanded "><a href="ch03-05-control-flow.html"><strong aria-hidden="true">3.5.</strong> Control Flow</a></li></ol></li><li class="expanded "><a href="ch04-00-understanding-ownership.html"><strong aria-hidden="true">4.</strong> Understanding Ownership</a></li><li><ol class="section"><li class="expanded "><a href="ch04-01-what-is-ownership.html"><strong aria-hidden="true">4.1.</strong> What is Ownership?</a></li><li class="expanded "><a href="ch04-02-references-and-borrowing.html"><strong aria-hidden="true">4.2.</strong> References and Borrowing</a></li><li class="expanded "><a href="ch04-03-slices.html"><strong aria-hidden="true">4.3.</strong> The Slice Type</a></li></ol></li><li class="expanded "><a href="ch05-00-structs.html"><strong aria-hidden="true">5.</strong> Using Structs to Structure Related Data</a></li><li><ol class="section"><li class="expanded "><a href="ch05-01-defining-structs.html"><strong aria-hidden="true">5.1.</strong> Defining and Instantiating Structs</a></li><li class="expanded "><a href="ch05-02-example-structs.html"><strong aria-hidden="true">5.2.</strong> An Example Program Using Structs</a></li><li class="expanded "><a href="ch05-03-method-syntax.html"><strong aria-hidden="true">5.3.</strong> Method Syntax</a></li></ol></li><li class="expanded "><a href="ch06-00-enums.html"><strong aria-hidden="true">6.</strong> Enums and Pattern Matching</a></li><li><ol class="section"><li class="expanded "><a href="ch06-01-defining-an-enum.html"><strong aria-hidden="true">6.1.</strong> Defining an Enum</a></li><li class="expanded "><a href="ch06-02-match.html"><strong aria-hidden="true">6.2.</strong> The match Control Flow Operator</a></li><li class="expanded "><a href="ch06-03-if-let.html"><strong aria-hidden="true">6.3.</strong> Concise Control Flow with if let</a></li></ol></li><li class="expanded "><a href="ch07-00-managing-growing-projects-with-packages-crates-and-modules.html"><strong aria-hidden="true">7.</strong> Managing Growing Projects with Packages, Crates, and Modules</a></li><li><ol class="section"><li class="expanded "><a href="ch07-01-packages-and-crates.html"><strong aria-hidden="true">7.1.</strong> Packages and Crates</a></li><li class="expanded "><a href="ch07-02-defining-modules-to-control-scope-and-privacy.html"><strong aria-hidden="true">7.2.</strong> Defining Modules to Control Scope and Privacy</a></li><li class="expanded "><a href="ch07-03-paths-for-referring-to-an-item-in-the-module-tree.html"><
|
|||
|
|
</div>
|
|||
|
|
<div id="sidebar-resize-handle" class="sidebar-resize-handle"></div>
|
|||
|
|
</nav>
|
|||
|
|
|
|||
|
|
<div id="page-wrapper" class="page-wrapper">
|
|||
|
|
|
|||
|
|
<div class="page">
|
|||
|
|
|
|||
|
|
<div id="menu-bar" class="menu-bar">
|
|||
|
|
<div id="menu-bar-sticky-container">
|
|||
|
|
<div class="left-buttons">
|
|||
|
|
<button id="sidebar-toggle" class="icon-button" type="button" title="Toggle Table of Contents" aria-label="Toggle Table of Contents" aria-controls="sidebar">
|
|||
|
|
<i class="fa fa-bars"></i>
|
|||
|
|
</button>
|
|||
|
|
<button id="theme-toggle" class="icon-button" type="button" title="Change theme" aria-label="Change theme" aria-haspopup="true" aria-expanded="false" aria-controls="theme-list">
|
|||
|
|
<i class="fa fa-paint-brush"></i>
|
|||
|
|
</button>
|
|||
|
|
<ul id="theme-list" class="theme-popup" aria-label="Themes" role="menu">
|
|||
|
|
<li role="none"><button role="menuitem" class="theme" id="light">Light (default)</button></li>
|
|||
|
|
<li role="none"><button role="menuitem" class="theme" id="rust">Rust</button></li>
|
|||
|
|
<li role="none"><button role="menuitem" class="theme" id="coal">Coal</button></li>
|
|||
|
|
<li role="none"><button role="menuitem" class="theme" id="navy">Navy</button></li>
|
|||
|
|
<li role="none"><button role="menuitem" class="theme" id="ayu">Ayu</button></li>
|
|||
|
|
</ul>
|
|||
|
|
|
|||
|
|
<button id="search-toggle" class="icon-button" type="button" title="Search. (Shortkey: s)" aria-label="Toggle Searchbar" aria-expanded="false" aria-keyshortcuts="S" aria-controls="searchbar">
|
|||
|
|
<i class="fa fa-search"></i>
|
|||
|
|
</button>
|
|||
|
|
|
|||
|
|
</div>
|
|||
|
|
|
|||
|
|
<h1 class="menu-title">The Rust Programming Language</h1>
|
|||
|
|
|
|||
|
|
<div class="right-buttons">
|
|||
|
|
<a href="print.html" title="Print this book" aria-label="Print this book">
|
|||
|
|
<i id="print-button" class="fa fa-print"></i>
|
|||
|
|
</a>
|
|||
|
|
|
|||
|
|
</div>
|
|||
|
|
</div>
|
|||
|
|
</div>
|
|||
|
|
|
|||
|
|
|
|||
|
|
<div id="search-wrapper" class="hidden">
|
|||
|
|
<form id="searchbar-outer" class="searchbar-outer">
|
|||
|
|
<input type="search" name="search" id="searchbar" name="searchbar" placeholder="Search this book ..." aria-controls="searchresults-outer" aria-describedby="searchresults-header">
|
|||
|
|
</form>
|
|||
|
|
<div id="searchresults-outer" class="searchresults-outer hidden">
|
|||
|
|
<div id="searchresults-header" class="searchresults-header"></div>
|
|||
|
|
<ul id="searchresults">
|
|||
|
|
</ul>
|
|||
|
|
</div>
|
|||
|
|
</div>
|
|||
|
|
|
|||
|
|
|
|||
|
|
<!-- Apply ARIA attributes after the sidebar and the sidebar toggle button are added to the DOM -->
|
|||
|
|
<script type="text/javascript">
|
|||
|
|
document.getElementById('sidebar-toggle').setAttribute('aria-expanded', sidebar === 'visible');
|
|||
|
|
document.getElementById('sidebar').setAttribute('aria-hidden', sidebar !== 'visible');
|
|||
|
|
Array.from(document.querySelectorAll('#sidebar a')).forEach(function(link) {
|
|||
|
|
link.setAttribute('tabIndex', sidebar === 'visible' ? 0 : -1);
|
|||
|
|
});
|
|||
|
|
</script>
|
|||
|
|
|
|||
|
|
<div id="content" class="content">
|
|||
|
|
<main>
|
|||
|
|
<h2><a class="header" href="#separating-modules-into-different-files" id="separating-modules-into-different-files">Separating Modules into Different Files</a></h2>
|
|||
|
|
<p>So far, all the examples in this chapter defined multiple modules in one file.
|
|||
|
|
When modules get large, you might want to move their definitions to a separate
|
|||
|
|
file to make the code easier to navigate.</p>
|
|||
|
|
<p>For example, let’s start from the code in Listing 7-17 and move the
|
|||
|
|
<code>front_of_house</code> module to its own file <em>src/front_of_house.rs</em> by changing the
|
|||
|
|
crate root file so it contains the code shown in Listing 7-21. In this case,
|
|||
|
|
the crate root file is <em>src/lib.rs</em>, but this procedure also works with binary
|
|||
|
|
crates whose crate root file is <em>src/main.rs</em>.</p>
|
|||
|
|
<p><span class="filename">Filename: src/lib.rs</span></p>
|
|||
|
|
<pre><code class="language-rust ignore">mod front_of_house;
|
|||
|
|
|
|||
|
|
pub use crate::front_of_house::hosting;
|
|||
|
|
|
|||
|
|
pub fn eat_at_restaurant() {
|
|||
|
|
hosting::add_to_waitlist();
|
|||
|
|
hosting::add_to_waitlist();
|
|||
|
|
hosting::add_to_waitlist();
|
|||
|
|
}
|
|||
|
|
</code></pre>
|
|||
|
|
<p><span class="caption">Listing 7-21: Declaring the <code>front_of_house</code> module whose
|
|||
|
|
body will be in <em>src/front_of_house.rs</em></span></p>
|
|||
|
|
<p>And <em>src/front_of_house.rs</em> gets the definitions from the body of the
|
|||
|
|
<code>front_of_house</code> module, as shown in Listing 7-22.</p>
|
|||
|
|
<p><span class="filename">Filename: src/front_of_house.rs</span></p>
|
|||
|
|
<pre><pre class="playpen"><code class="language-rust">
|
|||
|
|
<span class="boring">#![allow(unused_variables)]
|
|||
|
|
</span><span class="boring">fn main() {
|
|||
|
|
</span>pub mod hosting {
|
|||
|
|
pub fn add_to_waitlist() {}
|
|||
|
|
}
|
|||
|
|
<span class="boring">}
|
|||
|
|
</span></code></pre></pre>
|
|||
|
|
<p><span class="caption">Listing 7-22: Definitions inside the <code>front_of_house</code>
|
|||
|
|
module in <em>src/front_of_house.rs</em></span></p>
|
|||
|
|
<p>Using a semicolon after <code>mod front_of_house</code> rather than using a block tells
|
|||
|
|
Rust to load the contents of the module from another file with the same name as
|
|||
|
|
the module. To continue with our example and extract the <code>hosting</code> module to
|
|||
|
|
its own file as well, we change <em>src/front_of_house.rs</em> to contain only the
|
|||
|
|
declaration of the <code>hosting</code> module:</p>
|
|||
|
|
<p><span class="filename">Filename: src/front_of_house.rs</span></p>
|
|||
|
|
<pre><code>pub mod hosting;
|
|||
|
|
</code></pre>
|
|||
|
|
<p>Then we create a <em>src/front_of_house</em> directory and a file
|
|||
|
|
<em>src/front_of_house/hosting.rs</em> to contain the definitions made in the
|
|||
|
|
<code>hosting</code> module:</p>
|
|||
|
|
<p><span class="filename">Filename: src/front_of_house/hosting.rs</span></p>
|
|||
|
|
<pre><code>pub fn add_to_waitlist() {}
|
|||
|
|
</code></pre>
|
|||
|
|
<p>The module tree remains the same, and the function calls in <code>eat_at_restaurant</code>
|
|||
|
|
will work without any modification, even though the definitions live in
|
|||
|
|
different files. This technique lets you move modules to new files as they grow
|
|||
|
|
in size.</p>
|
|||
|
|
<p>Note that the <code>pub use crate::front_of_house::hosting</code> statement in
|
|||
|
|
<em>src/lib.rs</em> also hasn’t changed, nor does <code>use</code> have any impact on what files
|
|||
|
|
are compiled as part of the crate. The <code>mod</code> keyword declares modules, and Rust
|
|||
|
|
looks in a file with the same name as the module for the code that goes into
|
|||
|
|
that module.</p>
|
|||
|
|
<h2><a class="header" href="#summary" id="summary">Summary</a></h2>
|
|||
|
|
<p>Rust lets you split a package into multiple crates and a crate into modules
|
|||
|
|
so you can refer to items defined in one module from another module. You can do
|
|||
|
|
this by specifying absolute or relative paths. These paths can be brought into
|
|||
|
|
scope with a <code>use</code> statement so you can use a shorter path for multiple uses of
|
|||
|
|
the item in that scope. Module code is private by default, but you can make
|
|||
|
|
definitions public by adding the <code>pub</code> keyword.</p>
|
|||
|
|
<p>In the next chapter, we’ll look at some collection data structures in the
|
|||
|
|
standard library that you can use in your neatly organized code.</p>
|
|||
|
|
|
|||
|
|
</main>
|
|||
|
|
|
|||
|
|
<nav class="nav-wrapper" aria-label="Page navigation">
|
|||
|
|
<!-- Mobile navigation buttons -->
|
|||
|
|
|
|||
|
|
<a rel="prev" href="ch07-04-bringing-paths-into-scope-with-the-use-keyword.html" class="mobile-nav-chapters previous" title="Previous chapter" aria-label="Previous chapter" aria-keyshortcuts="Left">
|
|||
|
|
<i class="fa fa-angle-left"></i>
|
|||
|
|
</a>
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
<a rel="next" href="ch08-00-common-collections.html" class="mobile-nav-chapters next" title="Next chapter" aria-label="Next chapter" aria-keyshortcuts="Right">
|
|||
|
|
<i class="fa fa-angle-right"></i>
|
|||
|
|
</a>
|
|||
|
|
|
|||
|
|
|
|||
|
|
<div style="clear: both"></div>
|
|||
|
|
</nav>
|
|||
|
|
</div>
|
|||
|
|
</div>
|
|||
|
|
|
|||
|
|
<nav class="nav-wide-wrapper" aria-label="Page navigation">
|
|||
|
|
|
|||
|
|
<a href="ch07-04-bringing-paths-into-scope-with-the-use-keyword.html" class="nav-chapters previous" title="Previous chapter" aria-label="Previous chapter" aria-keyshortcuts="Left">
|
|||
|
|
<i class="fa fa-angle-left"></i>
|
|||
|
|
</a>
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
<a href="ch08-00-common-collections.html" class="nav-chapters next" title="Next chapter" aria-label="Next chapter" aria-keyshortcuts="Right">
|
|||
|
|
<i class="fa fa-angle-right"></i>
|
|||
|
|
</a>
|
|||
|
|
|
|||
|
|
</nav>
|
|||
|
|
|
|||
|
|
</div>
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
<script type="text/javascript">
|
|||
|
|
window.playpen_copyable = true;
|
|||
|
|
</script>
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
<script src="elasticlunr.min.js" type="text/javascript" charset="utf-8"></script>
|
|||
|
|
<script src="mark.min.js" type="text/javascript" charset="utf-8"></script>
|
|||
|
|
<script src="searcher.js" type="text/javascript" charset="utf-8"></script>
|
|||
|
|
|
|||
|
|
|
|||
|
|
<script src="clipboard.min.js" type="text/javascript" charset="utf-8"></script>
|
|||
|
|
<script src="highlight.js" type="text/javascript" charset="utf-8"></script>
|
|||
|
|
<script src="book.js" type="text/javascript" charset="utf-8"></script>
|
|||
|
|
|
|||
|
|
<!-- Custom JS scripts -->
|
|||
|
|
|
|||
|
|
<script type="text/javascript" src="ferris.js"></script>
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
</body>
|
|||
|
|
</html>
|