From 250a508cbf5cf17404d1b010c508333c417b708f Mon Sep 17 00:00:00 2001 From: Sean Liao Date: Wed, 15 May 2024 03:52:23 +0100 Subject: [go/en] update for modern go (#4678) --- go.html.markdown | 65 ++++++++++++++++++++++++++++++-------------------------- 1 file changed, 35 insertions(+), 30 deletions(-) diff --git a/go.html.markdown b/go.html.markdown index 59ba2e4f..b93cbc61 100644 --- a/go.html.markdown +++ b/go.html.markdown @@ -32,11 +32,11 @@ Go comes with a good standard library and a sizeable community. /* Multi- line comment */ - /* A build tag is a line comment starting with // +build + /* A build tag is a line comment starting with //go:build and can be executed by go build -tags="foo bar" command. Build tags are placed before the package clause near or at the top of the file followed by a blank line or other line comments. */ -// +build prod, dev, test +//go:build prod || dev || test // A package clause starts every source file. // main is a special name declaring an executable rather than a library. @@ -44,12 +44,13 @@ package main // Import declaration declares library packages referenced in this file. import ( - "fmt" // A package in the Go standard library. - "io/ioutil" // Implements some I/O utility functions. - m "math" // Math library with local alias m. - "net/http" // Yes, a web server! - "os" // OS functions like working with the file system - "strconv" // String conversions. + "fmt" // A package in the Go standard library. + "io" // Implements some I/O utility functions. + m "math" // Math library with local alias m. + "net/http" // Yes, a web server! + _ "net/http/pprof" // Profiling library imported only for side effects + "os" // OS functions like working with the file system + "strconv" // String conversions. ) // A function definition. Main is special. It is the entry point for the @@ -106,13 +107,13 @@ can include line breaks.` // Same string type. n := byte('\n') // byte is an alias for uint8. // Arrays have size fixed at compile time. - var a4 [4]int // An array of 4 ints, initialized to all 0. + var a4 [4]int // An array of 4 ints, initialized to all 0. a5 := [...]int{3, 1, 5, 10, 100} // An array initialized with a fixed size of five // elements, with values 3, 1, 5, 10, and 100. // Arrays have value semantics. - a4_cpy := a4 // a4_cpy is a copy of a4, two separate instances. - a4_cpy[0] = 25 // Only a4_cpy is changed, a4 stays the same. + a4_cpy := a4 // a4_cpy is a copy of a4, two separate instances. + a4_cpy[0] = 25 // Only a4_cpy is changed, a4 stays the same. fmt.Println(a4_cpy[0] == a4[0]) // false // Slices have dynamic size. Arrays and slices each have advantages @@ -123,24 +124,24 @@ can include line breaks.` // Same string type. bs := []byte("a slice") // Type conversion syntax. // Slices (as well as maps and channels) have reference semantics. - s3_cpy := s3 // Both variables point to the same instance. - s3_cpy[0] = 0 // Which means both are updated. - fmt.Println(s3_cpy[0] == s3[0]) // true + s3_cpy := s3 // Both variables point to the same instance. + s3_cpy[0] = 0 // Which means both are updated. + fmt.Println(s3_cpy[0] == s3[0]) // true // Because they are dynamic, slices can be appended to on-demand. // To append elements to a slice, the built-in append() function is used. // First argument is a slice to which we are appending. Commonly, // the slice variable is updated in place, as in example below. - s := []int{1, 2, 3} // Result is a slice of length 3. - s = append(s, 4, 5, 6) // Added 3 elements. Slice now has length of 6. - fmt.Println(s) // Updated slice is now [1 2 3 4 5 6] + s := []int{1, 2, 3} // Result is a slice of length 3. + s = append(s, 4, 5, 6) // Added 3 elements. Slice now has length of 6. + fmt.Println(s) // Updated slice is now [1 2 3 4 5 6] // To append another slice, instead of list of atomic elements we can // pass a reference to a slice or a slice literal like this, with a // trailing ellipsis, meaning take a slice and unpack its elements, // appending them to slice s. s = append(s, []int{7, 8, 9}...) // Second argument is a slice literal. - fmt.Println(s) // Updated slice is now [1 2 3 4 5 6 7 8 9] + fmt.Println(s) // Updated slice is now [1 2 3 4 5 6 7 8 9] p, q := learnMemory() // Declares p, q to be type pointer to int. fmt.Println(*p, *q) // * follows a pointer. This prints two ints. @@ -160,7 +161,7 @@ can include line breaks.` // Same string type. file, _ := os.Create("output.txt") fmt.Fprint(file, "This is how you write to a file, by the way") file.Close() - + // Output of course counts as using a variable. fmt.Println(s, c, a4, s3, d2, m) @@ -179,7 +180,7 @@ func learnNamedReturns(x, y int) (z int) { // Go is fully garbage collected. It has pointers but no pointer arithmetic. // You can make a mistake with a nil pointer, but not by incrementing a pointer. -// Unlike in C/Cpp taking and returning an address of a local variable is also safe. +// Unlike in C/Cpp taking and returning an address of a local variable is also safe. func learnMemory() (p, q *int) { // Named return values p and q have type pointer to int. p = new(int) // Built-in function new allocates memory. @@ -190,7 +191,7 @@ func learnMemory() (p, q *int) { return &s[3], &r // & takes the address of an object. } -// Use the aliased math library (see imports, above) +// Use the aliased math library (see imports, above) func expensiveComputation() float64 { return m.Exp(10) } @@ -214,8 +215,8 @@ func learnFlowControl() { case 42: // Cases don't "fall through". /* - There is a `fallthrough` keyword however, see: - https://github.com/golang/go/wiki/Switch#fall-through + There is a `fallthrough` keyword however, see: + https://github.com/golang/go/wiki/Switch#fall-through */ case 43: // Unreached. @@ -355,7 +356,7 @@ func learnInterfaces() { } // Functions can have variadic parameters. -func learnVariadicParams(myStrings ...interface{}) { +func learnVariadicParams(myStrings ...any) { // any is an alias for interface{} // Iterate each value of the variadic. // The underscore here is ignoring the index argument of the array. for _, param := range myStrings { @@ -428,7 +429,6 @@ func learnConcurrency() { // A single function from package http starts a web server. func learnWebProgramming() { - // First parameter of ListenAndServe is TCP address to listen to. // Second parameter is an interface, specifically http.Handler. go func() { @@ -449,7 +449,7 @@ func requestServer() { resp, err := http.Get("http://localhost:8080") fmt.Println(err) defer resp.Body.Close() - body, err := ioutil.ReadAll(resp.Body) + body, err := io.ReadAll(resp.Body) fmt.Printf("\nWebserver said: `%s`", string(body)) } ``` @@ -457,20 +457,23 @@ func requestServer() { ## Further Reading The root of all things Go is the [official Go web site](https://go.dev/). -There you can follow the tutorial, play interactively, and read lots. +There you can follow the [tutorial](https://go.dev/tour/), play interactively, and read lots. Aside from a tour, [the docs](https://go.dev/doc/) contain information on how to write clean and effective Go code, package and command docs, and release history. The [Go language specification](https://go.dev/ref/spec) itself is highly recommended. It's easy to read and amazingly short (as language definitions go these days.) -You can play around with the code on [Go playground](https://go.dev/play/p/tnWMjr16Mm). Try to change it and run it from your browser! Note that you can use [https://go.dev/play/](https://go.dev/play/) as a [REPL](https://en.wikipedia.org/wiki/Read-eval-print_loop) to test things and code in your browser, without even installing Go. +You can play around with the code on [Go playground](https://go.dev/play/p/Y96bRpJWzjr). +Try to change it and run it from your browser! +Note that you can use [https://go.dev/play/](https://go.dev/play/) +as a [REPL](https://en.wikipedia.org/wiki/Read-eval-print_loop) to test things and code in your browser, without even installing Go. On the reading list for students of Go is the [source code to the standard library](https://go.dev/src/). Comprehensively documented, it demonstrates the best of readable and understandable Go, Go style, and Go idioms. Or you can click on a function name in [the -documentation](https://go.dev/pkg/) and the source code comes up! +documentation](https://pkg.go.dev/std) and the source code comes up! Another great resource to learn Go is [Go by example](https://gobyexample.com/). @@ -480,4 +483,6 @@ There are many excellent conference talks and video tutorials on Go available on - [Golang University 201](https://www.youtube.com/playlist?list=PLEcwzBXTPUE_5m_JaMXmGEFgduH8EsuTs) steps it up a notch, explaining important techniques like testing, web services, and APIs - [Golang University 301](https://www.youtube.com/playlist?list=PLEcwzBXTPUE8KvXRFmmfPEUmKoy9LfmAf) dives into more advanced topics like the Go scheduler, implementation of maps and channels, and optimisation techniques -Go Mobile adds support for mobile platforms (Android and iOS). You can write all-Go native mobile apps or write a library that contains bindings from a Go package, which can be invoked via Java (Android) and Objective-C (iOS). Check out the [Go Mobile page](https://github.com/golang/go/wiki/Mobile) for more information. +Go Mobile adds support for mobile platforms (Android and iOS). +You can write all-Go native mobile apps or write a library that contains bindings from a Go package, +which can be invoked via Java (Android) and Objective-C (iOS). Check out the [Go Mobile page](https://github.com/golang/go/wiki/Mobile) for more information. -- cgit v1.2.3