Add embed-directive example and rename embedding to struct-embedding
Signed-off-by: peterzhu1992 <peterzhu1992@gmail.com>
This commit is contained in:
peterzhu1992
parent
9deadb76ae
commit
f900918c93
@ -19,7 +19,8 @@ Strings and Runes
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Structs
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Methods
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Interfaces
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Embedding
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Struct Embedding
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Embed Directive
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Generics
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Errors
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Goroutines
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51
examples/embed-directive/embed-directive.go
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51
examples/embed-directive/embed-directive.go
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@ -0,0 +1,51 @@
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// Starting in Go version 1.16+, Go supports use of `//go:embed`
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// which is a directive to embed files and folders into
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// the application binary by the compiler.
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// Since Go does not have preprocessor or macros like C type of languages,
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// `pragmas/directives` are implemented by the compiler as comments `//`.
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// Using `//go:embed` tells the compiler to include arbitrary files/folders in binary.
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package main
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// If you are not using any exported identifiers from `embed` package directly,
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// you can add an underscore `_` before the package name, ask Go to import `embed`
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// without directly using it, like this: `_ "embed"`. In this example, we remove the
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// underscore as we need to use the `embed.FS` type from the package.
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import (
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"embed"
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)
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// Since one file is defined after the directive, the compiler will only include
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// this single file, followed by variable `single_file_string` to access as `string` type.
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//go:embed embed-directive.sh
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var single_file_string string
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// Here is a similar example but include single file as `[]byte`.
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// Note that `//go:embed` can only be used in package level,
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// define it in any function will result in error.
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//go:embed embed-directive.sh
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var single_file_byte []byte
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// We can also embed multiple files or even folders with wildcard.
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// Since Go resolves these files and folders during compile time, we have to use the files in
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// current working directory as examples. In practice, you can embed files with `"//go:embed /path/to/folder"`
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// or with another example `"//go:embed /path/to/folder/*"`. You can add multiple `//go:embed` before defining a variable.
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//go:embed *.hash
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//go:embed embed-directive.sh
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var folder_FS embed.FS
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func main() {
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// Print out the content of `embed-directive.sh` as `string`.
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println(single_file_string)
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// Print out the content of `embed-directive.sh` as `[]byte`.
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println(string(single_file_byte))
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// Print out the content of `embed-directive.hash` by reading the file from `folder_FS` first,
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// then print out the content.
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hash_file := "embed-directive.hash"
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hash_content, _ := folder_FS.ReadFile(hash_file)
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println(string(hash_content))
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}
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2
examples/embed-directive/embed-directive.hash
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2
examples/embed-directive/embed-directive.hash
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@ -0,0 +1,2 @@
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10914400b16498094a1a876856181673c3fcdfe0
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gk3Zh5Sx8rV
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4
examples/embed-directive/embed-directive.sh
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4
examples/embed-directive/embed-directive.sh
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@ -0,0 +1,4 @@
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# Use these commands to run the example
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$ go run embed-directive.go
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@ -1,2 +0,0 @@
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316e334f61f03d59c8a45889a057903a786534ba
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k5Z_CnP8DK9
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@ -1,5 +1,8 @@
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// Go supports _embedding_ of structs and interfaces
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// to express a more seamless _composition_ of types.
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// This is not to be confused with _go:embed_ which is
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// a go directive introduced in go version 1.16 to embed
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// files and folders into the application binary.
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package main
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2
examples/struct-embedding/struct-embedding.hash
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2
examples/struct-embedding/struct-embedding.hash
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@ -0,0 +1,2 @@
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8ec60ccaf4c5803bd65a776e05b458b008ae52a7
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4B33kwDJ3fm
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222
public/embed-directive
generated
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222
public/embed-directive
generated
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@ -0,0 +1,222 @@
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<!DOCTYPE html>
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<html>
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<head>
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<meta charset="utf-8">
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<title>Go by Example: Embed Directive</title>
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<link rel=stylesheet href="site.css">
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</head>
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<script>
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onkeydown = (e) => {
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if (e.key == "ArrowLeft") {
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window.location.href = 'struct-embedding';
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}
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if (e.key == "ArrowRight") {
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window.location.href = 'generics';
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}
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}
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</script>
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<body>
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<div class="example" id="embed-directive">
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<h2><a href="./">Go by Example</a>: Embed Directive</h2>
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<table>
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<tr>
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<td class="docs">
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<p>Starting in Go version 1.16+, Go supports use of <code>//go:embed</code>
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which is a directive to embed files and folders into
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the application binary by the compiler.</p>
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</td>
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<td class="code empty leading">
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</td>
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</tr>
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<tr>
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<td class="docs">
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<p>Since Go does not have preprocessor or macros like C type of languages,
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<code>pragmas/directives</code> are implemented by the compiler as comments <code>//</code>.
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Using <code>//go:embed</code> tells the compiler to include arbitrary files/folders in binary.</p>
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</td>
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<td class="code leading">
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<a href="http://play.golang.org/p/gk3Zh5Sx8rV"><img title="Run code" src="play.png" class="run" /></a><img title="Copy code" src="clipboard.png" class="copy" />
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<pre class="chroma">
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<span class="kn">package</span> <span class="nx">main</span>
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</pre>
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</td>
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</tr>
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<tr>
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<td class="docs">
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<p>If you are not using any exported identifiers from <code>embed</code> package directly,
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you can add an underscore <code>_</code> before the package name, ask Go to import <code>embed</code>
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without directly using it, like this: <code>_ "embed"</code>. In this example, we remove the
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underscore as we need to use the <code>embed.FS</code> type from the package.</p>
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</td>
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<td class="code leading">
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<pre class="chroma">
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<span class="kn">import</span> <span class="p">(</span>
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<span class="s">"embed"</span>
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<span class="p">)</span>
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</pre>
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</td>
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</tr>
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<tr>
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<td class="docs">
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<p>Since one file is defined after the directive, the compiler will only include
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this single file, followed by variable <code>single_file_string</code> to access as <code>string</code> type.</p>
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</td>
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<td class="code leading">
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<pre class="chroma">
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<span class="c1">//go:embed embed-directive.sh
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</span><span class="c1"></span><span class="kd">var</span> <span class="nx">single_file_string</span> <span class="kt">string</span>
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</pre>
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</td>
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</tr>
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<tr>
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<td class="docs">
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<p>Here is a similar example but include single file as <code>[]byte</code>.
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Note that <code>//go:embed</code> can only be used in package level,
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define it in any function will result in error.</p>
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</td>
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<td class="code leading">
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<pre class="chroma">
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<span class="c1">//go:embed embed-directive.sh
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</span><span class="c1"></span><span class="kd">var</span> <span class="nx">single_file_byte</span> <span class="p">[]</span><span class="kt">byte</span>
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</pre>
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</td>
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</tr>
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<tr>
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<td class="docs">
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<p>We can also embed multiple files or even folders with wildcard.
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Since Go resolves these files and folders during compile time, we have to use the files in
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current working directory as examples. In practice, you can embed files with <code>"//go:embed /path/to/folder"</code>
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or with another example <code>"//go:embed /path/to/folder/*"</code>. You can add multiple <code>//go:embed</code> before defining a variable.</p>
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</td>
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<td class="code leading">
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<pre class="chroma">
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<span class="c1">//go:embed *.hash
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</span><span class="c1">//go:embed embed-directive.sh
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</span><span class="c1"></span><span class="kd">var</span> <span class="nx">folder_FS</span> <span class="nx">embed</span><span class="p">.</span><span class="nx">FS</span>
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</pre>
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</td>
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</tr>
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<tr>
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<td class="docs">
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</td>
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<td class="code leading">
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<pre class="chroma"><span class="kd">func</span> <span class="nf">main</span><span class="p">()</span> <span class="p">{</span>
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</pre>
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</td>
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</tr>
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<tr>
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<td class="docs">
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<p>Print out the content of <code>embed-directive.sh</code> as <code>string</code>.</p>
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</td>
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<td class="code leading">
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<pre class="chroma">
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<span class="nb">println</span><span class="p">(</span><span class="nx">single_file_string</span><span class="p">)</span>
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</pre>
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</td>
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</tr>
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<tr>
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<td class="docs">
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<p>Print out the content of <code>embed-directive.sh</code> as <code>[]byte</code>.</p>
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</td>
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<td class="code leading">
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<pre class="chroma">
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<span class="nb">println</span><span class="p">(</span><span class="nb">string</span><span class="p">(</span><span class="nx">single_file_byte</span><span class="p">))</span>
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</pre>
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</td>
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</tr>
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<tr>
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<td class="docs">
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<p>Print out the content of <code>embed-directive.hash</code> by reading the file from <code>folder_FS</code> first,
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then print out the content.</p>
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</td>
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<td class="code leading">
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<pre class="chroma">
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<span class="nx">hash_file</span> <span class="o">:=</span> <span class="s">"embed-directive.hash"</span>
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<span class="nx">hash_content</span><span class="p">,</span> <span class="nx">_</span> <span class="o">:=</span> <span class="nx">folder_FS</span><span class="p">.</span><span class="nf">ReadFile</span><span class="p">(</span><span class="nx">hash_file</span><span class="p">)</span>
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<span class="nb">println</span><span class="p">(</span><span class="nb">string</span><span class="p">(</span><span class="nx">hash_content</span><span class="p">))</span>
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</pre>
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</td>
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</tr>
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<tr>
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<td class="docs">
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</td>
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<td class="code">
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<pre class="chroma"><span class="p">}</span>
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</pre>
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</td>
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</tr>
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</table>
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<table>
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<tr>
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<td class="docs">
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<p>Use these commands to run the example</p>
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</td>
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<td class="code">
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<pre class="chroma">
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<span class="gp">$</span> go run embed-directive.go</pre>
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</td>
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</tr>
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</table>
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<p class="next">
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Next example: <a href="generics">Generics</a>.
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</p>
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<p class="footer">
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by <a href="https://markmcgranaghan.com">Mark McGranaghan</a> and <a href="https://eli.thegreenplace.net">Eli Bendersky</a> | <a href="https://github.com/mmcgrana/gobyexample">source</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a>
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</p>
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</div>
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<script>
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var codeLines = [];
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codeLines.push('');codeLines.push('package main\u000A');codeLines.push('import (\u000A \"embed\"\u000A)\u000A');codeLines.push('//go:embed embed-directive.sh\u000Avar single_file_string string\u000A');codeLines.push('//go:embed embed-directive.sh\u000Avar single_file_byte []byte\u000A');codeLines.push('//go:embed *.hash\u000A//go:embed embed-directive.sh\u000Avar folder_FS embed.FS\u000A');codeLines.push('func main() {\u000A');codeLines.push(' println(single_file_string)\u000A');codeLines.push(' println(string(single_file_byte))\u000A');codeLines.push(' hash_file :\u003D \"embed-directive.hash\"\u000A hash_content, _ :\u003D folder_FS.ReadFile(hash_file)\u000A println(string(hash_content))\u000A');codeLines.push('}\u000A');codeLines.push('');
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</script>
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<script src="site.js" async></script>
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</body>
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</html>
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2
public/generics
generated
2
public/generics
generated
@ -9,7 +9,7 @@
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onkeydown = (e) => {
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if (e.key == "ArrowLeft") {
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window.location.href = 'embedding';
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window.location.href = 'embed-directive';
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}
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4
public/index.html
generated
4
public/index.html
generated
@ -69,7 +69,9 @@
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<li><a href="interfaces">Interfaces</a></li>
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<li><a href="embedding">Embedding</a></li>
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<li><a href="struct-embedding">Struct Embedding</a></li>
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<li><a href="embed-directive">Embed Directive</a></li>
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<li><a href="generics">Generics</a></li>
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4
public/interfaces
generated
4
public/interfaces
generated
@ -14,7 +14,7 @@
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if (e.key == "ArrowRight") {
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window.location.href = 'embedding';
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window.location.href = 'struct-embedding';
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}
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}
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@ -222,7 +222,7 @@ these structs as arguments to <code>measure</code>.</p>
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<p class="next">
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Next example: <a href="embedding">Embedding</a>.
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Next example: <a href="struct-embedding">Struct Embedding</a>.
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</p>
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17
public/embedding → public/struct-embedding
generated
17
public/embedding → public/struct-embedding
generated
@ -2,7 +2,7 @@
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<html>
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<head>
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<meta charset="utf-8">
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<title>Go by Example: Embedding</title>
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<title>Go by Example: Struct Embedding</title>
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<link rel=stylesheet href="site.css">
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</head>
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<script>
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@ -14,21 +14,24 @@
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if (e.key == "ArrowRight") {
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window.location.href = 'generics';
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window.location.href = 'embed-directive';
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}
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}
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</script>
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<body>
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<div class="example" id="embedding">
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<h2><a href="./">Go by Example</a>: Embedding</h2>
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<div class="example" id="struct-embedding">
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<h2><a href="./">Go by Example</a>: Struct Embedding</h2>
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<table>
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<tr>
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<td class="docs">
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<p>Go supports <em>embedding</em> of structs and interfaces
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to express a more seamless <em>composition</em> of types.</p>
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to express a more seamless <em>composition</em> of types.
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This is not to be confused with <em>go:embed</em> which is
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a go directive introduced in go version 1.16 to embed
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files and folders into the application binary.</p>
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</td>
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<td class="code empty leading">
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@ -42,7 +45,7 @@ to express a more seamless <em>composition</em> of types.</p>
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</td>
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<td class="code leading">
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<a href="http://play.golang.org/p/k5Z_CnP8DK9"><img title="Run code" src="play.png" class="run" /></a><img title="Copy code" src="clipboard.png" class="copy" />
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<a href="http://play.golang.org/p/4B33kwDJ3fm"><img title="Run code" src="play.png" class="run" /></a><img title="Copy code" src="clipboard.png" class="copy" />
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<pre class="chroma"><span class="kn">package</span> <span class="nx">main</span>
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</pre>
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</td>
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@ -230,7 +233,7 @@ we see that a <code>container</code> now implements the
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<p class="next">
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Next example: <a href="generics">Generics</a>.
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Next example: <a href="embed-directive">Embed Directive</a>.
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</p>
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