Resolve conflicts

.gitattributes

@@ -0,0 +1,3 @@
+public/* linguist-generated=true
+vendor/* linguist-vendored=true
+

.gitignore

@@ -1 +1,3 @@
 *.pyc
+.idea
+.vscode

.travis.yml

@@ -15,4 +15,4 @@ script:
   - tools/build
 
 env:
-  - VERBOSE=1
+  - VERBOSE=1 TESTING=1

CONTRIBUTING.md

@@ -2,9 +2,11 @@
 
 Thanks for your interest in contributing to Go by Example!
 
-* If you see a typo or would like to suggest another small change, editing the
-  .go or .sh source file should be sufficient for the PR. I can rebuild the
-  HTML when I review the change.
+* When sending a PR that affects the displayed contents of the site, run
+  `tools/build` locally and include the generated HTML in the PR. If you
+  only want to submit a simple typo suggestion (for example, through the
+  Github website), feel free to send a PR anyway - we'll regenerate the
+  HTML and merge with your commit.
 
 * We're open to adding more examples to the site. They should be on things
   used by many programmers and only require the standard library. If you're

examples.txt

@@ -46,6 +46,7 @@ String Functions
 String Formatting
 Regular Expressions
 JSON
+XML
 Time
 Epoch
 Time Formatting / Parsing
@@ -58,6 +59,8 @@ Reading Files
 Writing Files
 Line Filters
 File Paths
+Directories
+Temporary Files and Directories
 Command-Line Arguments
 Command-Line Flags
 Command-Line Subcommands

examples/atomic-counters/atomic-counters.go

@@ -7,9 +7,11 @@
 
 package main
 
-import "fmt"
-import "time"
-import "sync/atomic"
+import (
+	"fmt"
+	"sync"
+	"sync/atomic"
+)
 
 func main() {
 
@@ -17,33 +19,34 @@ func main() {
 	// (always-positive) counter.
 	var ops uint64
 
-	// To simulate concurrent updates, we'll start 50
-	// goroutines that each increment the counter about
-	// once a millisecond.
+	// A WaitGroup will help us wait for all goroutines
+	// to finish their work.
+	var wg sync.WaitGroup
+
+	// We'll start 50 goroutines that each increment the
+	// counter exactly 1000 times.
 	for i := 0; i < 50; i++ {
+		wg.Add(1)
+
 		go func() {
-			for {
+			for c := 0; c < 1000; c++ {
 				// To atomically increment the counter we
 				// use `AddUint64`, giving it the memory
 				// address of our `ops` counter with the
 				// `&` syntax.
 				atomic.AddUint64(&ops, 1)
-
-				// Wait a bit between increments.
-				time.Sleep(time.Millisecond)
 			}
+			wg.Done()
 		}()
 	}
 
-	// Wait a second to allow some ops to accumulate.
-	time.Sleep(time.Second)
+	// Wait until all the goroutines are done.
+	wg.Wait()
 
-	// In order to safely use the counter while it's still
-	// being updated by other goroutines, we extract a
-	// copy of the current value into `opsFinal` via
-	// `LoadUint64`. As above we need to give this
-	// function the memory address `&ops` from which to
-	// fetch the value.
-	opsFinal := atomic.LoadUint64(&ops)
-	fmt.Println("ops:", opsFinal)
+	// It's safe to access `ops` now because we know
+	// no other goroutine is writing to it. Reading
+	// atomics safely while they are being updated is
+	// also possible, using functions like
+	// `atomic.LoadUint64`.
+	fmt.Println("ops:", ops)
 }

examples/atomic-counters/atomic-counters.hash

@@ -1,2 +1,2 @@
-a4190094ea0405b5f2733101beb97939a1d43aee
-KDr9EMMPMgi
+8ebec0be3b167021c96b8b497d0e8c0a2ea99385
+F2pJfduyQiA

examples/atomic-counters/atomic-counters.sh

@@ -1,7 +1,11 @@
-# Running the program shows that we executed about
-# 40,000 operations.
+# We expect to get exactly 50,000 operations. Had we
+# used the non-atomic `ops++` to increment the counter,
+# we'd likely get a different number, changing between
+# runs, because the goroutines would interfere with
+# each other. Moreover, we'd get data race failures
+# when running with the `-race` flag.
 $ go run atomic-counters.go
-ops: 41419
+ops: 50000
 
 # Next we'll look at mutexes, another tool for managing
 # state.

examples/base64-encoding/base64-encoding.go

@@ -6,8 +6,10 @@ package main
 // This syntax imports the `encoding/base64` package with
 // the `b64` name instead of the default `base64`. It'll
 // save us some space below.
-import b64 "encoding/base64"
-import "fmt"
+import (
+	b64 "encoding/base64"
+	"fmt"
+)
 
 func main() {
 

examples/base64-encoding/base64-encoding.hash

@@ -1,2 +1,2 @@
-c20da14820b656c867790f2e99bc37140babca8c
-y_QTcqdkvZh
+e0148b9b4acb01e849b8f678cba03f549d250c44
+V3oV1bvh94k

examples/channel-synchronization/channel-synchronization.go

@@ -6,8 +6,10 @@
 
 package main
 
-import "fmt"
-import "time"
+import (
+	"fmt"
+	"time"
+)
 
 // This is the function we'll run in a goroutine. The
 // `done` channel will be used to notify another

examples/channel-synchronization/channel-synchronization.hash

@@ -1,2 +1,2 @@
-eb022977181884c2ab0f2b69e50311769e67a509
-8lmP8beav0p
+0d5a9de912e2a4a18943e082e2f8107cb75d0ce4
+fe9If6OhYMk

examples/collection-functions/collection-functions.go

@@ -18,8 +18,10 @@
 
 package main
 
-import "strings"
-import "fmt"
+import (
+	"fmt"
+	"strings"
+)
 
 // Index returns the first index of the target string `t`, or
 // -1 if no match is found.

examples/collection-functions/collection-functions.hash

@@ -1,2 +1,2 @@
-d961fc0e0074aed46cfd1516efdadea78781af56
-BJB_npWH516
+28456737ea996664bdaeb8e1e821d95697d00646
+8hI6oPNEfyh

examples/command-line-arguments/command-line-arguments.go

@@ -5,8 +5,10 @@
 
 package main
 
-import "os"
-import "fmt"
+import (
+	"fmt"
+	"os"
+)
 
 func main() {
 

examples/command-line-arguments/command-line-arguments.hash

@@ -1,2 +1,2 @@
-41c970a1ef29ad2a05307e6c783ff52ab80eaccd
-6pFdjf800jj
+9c80d495201148bbeb0fd0a5a2ce1735aeb34b60
+myJy_-H8Fo_Q

examples/command-line-flags/command-line-flags.go

@@ -8,8 +8,10 @@ package main
 // Go provides a `flag` package supporting basic
 // command-line flag parsing. We'll use this package to
 // implement our example command-line program.
-import "flag"
-import "fmt"
+import (
+	"flag"
+	"fmt"
+)
 
 func main() {
 

examples/command-line-flags/command-line-flags.hash

@@ -1,2 +1,2 @@
-e2ba0461c090789168c712cc7ed0f66aab09a8c8
-klFR5DitrCy
+ab08bf890dcd87b807956b5bee441d59efe458e3
+lPaZodnG9TF

examples/constants/constants.go

@@ -3,8 +3,10 @@
 
 package main
 
-import "fmt"
-import "math"
+import (
+	"fmt"
+	"math"
+)
 
 // `const` declares a constant value.
 const s string = "constant"

examples/constants/constants.hash

@@ -1,2 +1,2 @@
-2f2ec3a5ff4eef280199da1908eed261346fb40e
-VhP0f8moZd3
+7cc09460e8dc6fffd0ba811679f92a85eb51e927
+gmjHSglwLic

examples/defer/defer.go

@@ -5,8 +5,10 @@
 
 package main
 
-import "fmt"
-import "os"
+import (
+	"fmt"
+	"os"
+)
 
 // Suppose we wanted to create a file, write to it,
 // and then close when we're done. Here's how we could
@@ -40,5 +42,11 @@ func writeFile(f *os.File) {
 
 func closeFile(f *os.File) {
 	fmt.Println("closing")
-	f.Close()
+	err := f.Close()
+	// It's important to check for errors when closing a
+	// file, even in a deferred function.
+	if err != nil {
+		fmt.Fprintf(os.Stderr, "error: %v\n", err)
+		os.Exit(1)
+	}
 }

examples/defer/defer.hash

@@ -1,2 +1,2 @@
-570699fc50a1d39e9d0ad6a4461aef3248b080e1
-xPbQ5SGkH2O
+4fc23579a9bd5d8512884902394f4dce51eb7d60
+QJJ2R6kv6K5

examples/directories/directories.go

@@ -0,0 +1,95 @@
+// Go has several useful functions for working with
+// *directories* in the file system.
+
+package main
+
+import (
+	"fmt"
+	"io/ioutil"
+	"os"
+	"path/filepath"
+)
+
+func check(e error) {
+	if e != nil {
+		panic(e)
+	}
+}
+
+func main() {
+
+	// Create a new sub-directory in the current working
+	// directory.
+	err := os.Mkdir("subdir", 0755)
+	check(err)
+
+	// When creating temporary directories, it's good
+	// practice to `defer` their removal. `os.RemoveAll`
+	// will delete a whole directory tree (similarly to
+	// `rm -rf`).
+	defer os.RemoveAll("subdir")
+
+	// Helper function to create a new empty file.
+	createEmptyFile := func(name string) {
+		d := []byte("")
+		check(ioutil.WriteFile(name, d, 0644))
+	}
+
+	createEmptyFile("subdir/file1")
+
+	// We can create a hierarchy of directories, including
+	// parents with `MkdirAll`. This is similar to the
+	// command-line `mkdir -p`.
+	err = os.MkdirAll("subdir/parent/child", 0755)
+	check(err)
+
+	createEmptyFile("subdir/parent/file2")
+	createEmptyFile("subdir/parent/file3")
+	createEmptyFile("subdir/parent/child/file4")
+
+	// `ReadDir` lists directory contents, returning a
+	// slice of `os.FileInfo` objects.
+	c, err := ioutil.ReadDir("subdir/parent")
+	check(err)
+
+	fmt.Println("Listing subdir/parent")
+	for _, entry := range c {
+		fmt.Println(" ", entry.Name(), entry.IsDir())
+	}
+
+	// `Chdir` lets us change the current working directory,
+	// similarly to `cd`.
+	err = os.Chdir("subdir/parent/child")
+	check(err)
+
+	// Now we'll see the contents of `subdir/parent/child`
+	// when listing the *current* directory.
+	c, err = ioutil.ReadDir(".")
+	check(err)
+
+	fmt.Println("Listing subdir/parent/child")
+	for _, entry := range c {
+		fmt.Println(" ", entry.Name(), entry.IsDir())
+	}
+
+	// `cd` back to where we started.
+	err = os.Chdir("../../..")
+	check(err)
+
+	// We can also visit a directory *recursively*,
+	// including all its sub-directories. `Walk` accepts
+	// a callback function to handle every file or
+	// directory visited.
+	fmt.Println("Visiting subdir")
+	err = filepath.Walk("subdir", visit)
+}
+
+// `visit` is called for every file or directory found
+// recursively by `filepath.Walk`.
+func visit(p string, info os.FileInfo, err error) error {
+	if err != nil {
+		return err
+	}
+	fmt.Println(" ", p, info.IsDir())
+	return nil
+}

examples/directories/directories.hash

@@ -0,0 +1,2 @@
+83f67db91816b4544072d0a4d099111a21c60723
+-7kWq0PmATF

examples/directories/directories.sh

@@ -0,0 +1,15 @@
+$ go run directories.go
+Listing subdir/parent
+  child true
+  file2 false
+  file3 false
+Listing subdir/parent/child
+  file4 false
+Visiting subdir
+  subdir true
+  subdir/file1 false
+  subdir/parent true
+  subdir/parent/child true
+  subdir/parent/child/file4 false
+  subdir/parent/file2 false
+  subdir/parent/file3 false

examples/environment-variables/environment-variables.go

@@ -5,9 +5,11 @@
 
 package main
 
-import "os"
-import "strings"
-import "fmt"
+import (
+	"fmt"
+	"os"
+	"strings"
+)
 
 func main() {
 

examples/environment-variables/environment-variables.hash

@@ -1,2 +1,2 @@
-4d0832c5a1ddd4e95474791e8802c15452358214
-CZJ4R_uu6Uu
+db2e203da519a22943753295e9cc27d89e4347b0
+bKuCOOD16KH

examples/epoch/epoch.go

@@ -5,8 +5,10 @@
 
 package main
 
-import "fmt"
-import "time"
+import (
+	"fmt"
+	"time"
+)
 
 func main() {
 

examples/epoch/epoch.hash

@@ -1,2 +1,2 @@
-61a498229c8878a97d729cfdd215e5f3960f87ac
-eN1Qv2ATB-C
+184c8f3e94dd28176be81956115ac417e33513a6
+3uYNHHRplmQ

examples/errors/errors.go

@@ -9,8 +9,10 @@
 
 package main
 
-import "errors"
-import "fmt"
+import (
+	"errors"
+	"fmt"
+)
 
 // By convention, errors are the last return value and
 // have type `error`, a built-in interface.

examples/errors/errors.hash

@@ -1,2 +1,2 @@
-210ba0f8196006c0380acaec01655816848ef168
-mP_ZR1qjUvA
+ed58ad3162d93c723d3efe72529a61ce7041fe13
+vrwN32gxaYx

examples/execing-processes/execing-processes.go

@@ -10,9 +10,11 @@
 
 package main
 
-import "syscall"
-import "os"
-import "os/exec"
+import (
+	"os"
+	"os/exec"
+	"syscall"
+)
 
 func main() {
 

examples/execing-processes/execing-processes.hash

@@ -1,2 +1,2 @@
-b527bbb76a42dd4bae541b73a7377b7e83e79905
-bf11ADw-2Ho
+e6b4830d4264f307506b54726ec79b25a0363874
+ahZjpJaZz44

examples/exit/exit.go

@@ -3,8 +3,10 @@
 
 package main
 
-import "fmt"
-import "os"
+import (
+	"fmt"
+	"os"
+)
 
 func main() {
 

examples/exit/exit.hash

@@ -1,2 +1,2 @@
-dc0bb3eaafa045d6aa05e88aff39322a1ccf822e
-vDaM0-MGJ_k
+2316e6c8e364e2066c6bd350dc9b0b2af85b63fe
+OX997ykuOGx

examples/http-servers/http-servers.go

@@ -17,7 +17,7 @@ func hello(w http.ResponseWriter, req *http.Request) {
 	// Functions serving as handlers take a
 	// `http.ResponseWriter` and a `http.Request` as
 	// arguments. The response writer is used to fill in the
-	// HTTP response. Here out simple response is just
+	// HTTP response. Here our simple response is just
 	// "hello\n".
 	fmt.Fprintf(w, "hello\n")
 }

examples/http-servers/http-servers.hash

@@ -1,2 +1,2 @@
-ac2909e69be30862bd9f18db954d9ee10f57ec6a
-8GBAW6yNcbn
+a4e8d30b7a6f3a6abd96b916d81ce5930bad94f9
+lNuS9ysZmxH

examples/interfaces/interfaces.go

@@ -3,8 +3,10 @@
 
 package main
 
-import "fmt"
-import "math"
+import (
+	"fmt"
+	"math"
+)
 
 // Here's a basic interface for geometric shapes.
 type geometry interface {

examples/interfaces/interfaces.hash

@@ -1,2 +1,2 @@
-3547b935d1e0322c0fb696726c27cae53a275e0a
-0EwsqIn3TTi
+aac1328f5a04568272b82753ff0762b9eacff4fc
+hXTlbUAGcvn

examples/json/json.go

@@ -4,9 +4,11 @@
 
 package main
 
-import "encoding/json"
-import "fmt"
-import "os"
+import (
+	"encoding/json"
+	"fmt"
+	"os"
+)
 
 // We'll use these two structs to demonstrate encoding and
 // decoding of custom types below.
@@ -14,6 +16,9 @@ type response1 struct {
 	Page   int
 	Fruits []string
 }
+
+// Only exported fields will be encoded/decoded in JSON.
+// Fields must start with capital letters to be exported.
 type response2 struct {
 	Page   int      `json:"page"`
 	Fruits []string `json:"fruits"`

examples/json/json.hash

@@ -1,2 +1,2 @@
-d4dc2281f64061f077d8f1e9687538f41a339b25
-xC6SHbzGBZC
+c751bc7223b8bc615f82fe7643ab98ce2b80240f
+ROikmz5tRhZ

examples/number-parsing/number-parsing.go

@@ -5,8 +5,10 @@ package main
 
 // The built-in package `strconv` provides the number
 // parsing.
-import "strconv"
-import "fmt"
+import (
+	"fmt"
+	"strconv"
+)
 
 func main() {
 

examples/number-parsing/number-parsing.hash

@@ -1,2 +1,2 @@
-0d2155e9863a73c098d44637e92403d7f5e8e965
-NZh4LjhguvN
+0191c7e43706640207c403ba92dd2272d66fc868
+t2q4KnWWTAw

examples/random-numbers/random-numbers.go

@@ -4,9 +4,11 @@
 
 package main
 
-import "time"
-import "fmt"
-import "math/rand"
+import (
+	"fmt"
+	"math/rand"
+	"time"
+)
 
 func main() {
 

examples/random-numbers/random-numbers.hash

@@ -1,2 +1,2 @@
-8e97de760147b061dd09939db294c892211b6b80
-jiJaIjxL2sP
+9374869a809d28ea784a9e1181b4aa1988018776
+DVHO7SjJZnp

examples/rate-limiting/rate-limiting.go

@@ -6,8 +6,10 @@
 
 package main
 
-import "time"
-import "fmt"
+import (
+	"fmt"
+	"time"
+)
 
 func main() {
 

examples/rate-limiting/rate-limiting.hash

@@ -1,2 +1,2 @@
-edad78bf3b36ddc9bec30b344b8a72be4de90f3b
-l4uDE-RCDpa
+357d83df3e48675eb1e135188cb9f07448c1f146
+AJ-MJephNib

examples/regular-expressions/regular-expressions.go

@@ -4,9 +4,11 @@
 
 package main
 
-import "bytes"
-import "fmt"
-import "regexp"
+import (
+	"bytes"
+	"fmt"
+	"regexp"
+)
 
 func main() {
 

examples/regular-expressions/regular-expressions.hash

@@ -1,2 +1,2 @@
-7cde6b9af5cf6c47606001dd54eee468a6c61dbb
-qR5gn2l0AGa
+de24265897edf1d3913e3b87f70757284a66ecea
+urHlUNDVenk

examples/select/select.go

@@ -4,8 +4,10 @@
 
 package main
 
-import "time"
-import "fmt"
+import (
+	"fmt"
+	"time"
+)
 
 func main() {
 

examples/select/select.hash

@@ -1,2 +1,2 @@
-8d743edffd7de6bf7bccdf4437f45672b6adc75e
-ZdSOPe1Gj13
+6e1125087bc036ebd905452300575f160d683918
+yF-xgN7Xf9P

examples/sha1-hashes/sha1-hashes.go

@@ -9,8 +9,10 @@ package main
 
 // Go implements several hash functions in various
 // `crypto/*` packages.
-import "crypto/sha1"
-import "fmt"
+import (
+	"crypto/sha1"
+	"fmt"
+)
 
 func main() {
 	s := "sha1 this string"

examples/sha1-hashes/sha1-hashes.hash

@@ -1,2 +1,2 @@
-6a896270e34f2696b881a8fa7e68bfff57dee51f
-1oT-5GBUkLr
+4cda643ba233014fe6b30966c37d4d0fcd4edbe8
+oqcrTfY4Ykd

examples/signals/signals.go

@@ -7,10 +7,12 @@
 
 package main
 
-import "fmt"
-import "os"
-import "os/signal"
-import "syscall"
+import (
+	"fmt"
+	"os"
+	"os/signal"
+	"syscall"
+)
 
 func main() {
 

examples/signals/signals.hash

@@ -1,2 +1,2 @@
-9720d747e3ab2893df508a70cbb341c90fdd7ca1
-9koJAW1raI5
+1e43c6f63f1d57e1a52c89f52d35b68757e9676b
+_6oj-T3Gko2

examples/sorting-by-functions/sorting-by-functions.go

@@ -6,8 +6,10 @@
 
 package main
 
-import "sort"
-import "fmt"
+import (
+	"fmt"
+	"sort"
+)
 
 // In order to sort by a custom function in Go, we need a
 // corresponding type. Here we've created a `byLength`

examples/sorting-by-functions/sorting-by-functions.hash

@@ -1,2 +1,2 @@
-6a04058b564d5741815e523f97f240ee6563cb15
-y3kuCwIFRYK
+f7d0b7840dd12601fb86946f9dc4c38fb1c0501f
+Jtxf94x94Hx

examples/sorting/sorting.go

@@ -4,8 +4,10 @@
 
 package main
 
-import "fmt"
-import "sort"
+import (
+	"fmt"
+	"sort"
+)
 
 func main() {
 

examples/sorting/sorting.hash

@@ -1,2 +1,2 @@
-4e576421f2bdbd11847c367d223bd30d0e301990
-e6hp3Rn-oH6
+e11e944d34b21e75ce4f7c91026d4200ce592dc5
+tAWAkRlBJNX

examples/spawning-processes/spawning-processes.go

@@ -7,9 +7,11 @@
 
 package main
 
-import "fmt"
-import "io/ioutil"
-import "os/exec"
+import (
+	"fmt"
+	"io/ioutil"
+	"os/exec"
+)
 
 func main() {
 

examples/spawning-processes/spawning-processes.hash

@@ -1,2 +1,2 @@
-0b676b93e41ac5434003c194bc038d5f3ce76bc8
-6HRWVK5gPYU
+cc68e4290f10209ad2fa8db74fdfaea7fdb44d5c
+QS_Nkoe8VLG

examples/string-formatting/string-formatting.go

@@ -4,8 +4,10 @@
 
 package main
 
-import "fmt"
-import "os"
+import (
+	"fmt"
+	"os"
+)
 
 type point struct {
 	x, y int

examples/string-formatting/string-formatting.hash

@@ -1,2 +1,2 @@
-5f39ae6d8f26d59a688a9a9d7d13a5c1d0f7a08b
-CkBQ3CFpHQ9
+12b245c576b43537c092a5b84995ebca8ce78a57
+vmYSdxfUcRh

examples/string-functions/string-functions.go

@@ -4,8 +4,10 @@
 
 package main
 
-import s "strings"
-import "fmt"
+import (
+	"fmt"
+	s "strings"
+)
 
 // We alias `fmt.Println` to a shorter name as we'll use
 // it a lot below.

examples/string-functions/string-functions.hash

@@ -1,2 +1,2 @@
-17aa523bbd606fa0b624fae44b89812d46330755
-Vn4D3y4_711
+bf39c7540bd78eba38eb5a9047a9d0ffc7235f85
+xoRUhG86wsF

examples/structs/structs.go

@@ -12,6 +12,15 @@ type person struct {
 	age  int
 }
 
+// NewPerson constructs a new person struct with the given name
+func NewPerson(name string) *person {
+	// You can safely return a pointer to local variable
+	// as a local variable will survive the scope of the function.
+	p := person{name: name}
+	p.age = 42
+	return &p
+}
+
 func main() {
 
 	// This syntax creates a new struct.
@@ -26,6 +35,9 @@ func main() {
 	// An `&` prefix yields a pointer to the struct.
 	fmt.Println(&person{name: "Ann", age: 40})
 
+	// It's idiomatic to encapsulate new struct creation in constructor functions
+	fmt.Println(NewPerson("Jon"))
+
 	// Access struct fields with a dot.
 	s := person{name: "Sean", age: 50}
 	fmt.Println(s.name)

examples/structs/structs.hash

@@ -1,2 +1,2 @@
-49cad39331ee5e9fb8d8dad99d3aff7f18a4e6d0
-XMZpGsF4sWM
+c5caaf1eefaf084d688afb70d2ee5884a4983182
+00Yiw6xuICq

examples/structs/structs.sh

@@ -6,3 +6,4 @@ $ go run structs.go
 Sean
 50
 51
+&{Jon 42}

examples/switch/switch.go

@@ -3,8 +3,10 @@
 
 package main
 
-import "fmt"
-import "time"
+import (
+	"fmt"
+	"time"
+)
 
 func main() {
 

examples/switch/switch.hash

@@ -1,2 +1,2 @@
-b47004b3e3b6d787ea98642dc5b955df57cd2bcd
-TJ4Az0KuLfL
+2486fc553301cdeac9a26f3d0b3aed4143d9f4f0
+ZcDzdx3nYQn

examples/temporary-files-and-directories/temporary-files-and-directories.go

@@ -0,0 +1,65 @@
+// Throughout program execution, we often want to create
+// data that isn't needed after the program exits.
+// *Temporary files and directories* are useful for this
+// purpose since they don't pollute the file system over
+// time.
+
+package main
+
+import (
+	"fmt"
+	"io/ioutil"
+	"os"
+	"path/filepath"
+)
+
+func check(e error) {
+	if e != nil {
+		panic(e)
+	}
+}
+
+func main() {
+
+	// The easiest way to create a temporary file is by
+	// calling `ioutil.TempFile`. It creates a file *and*
+	// opens it for reading and writing. We provide `""`
+	// as the first argument, so `ioutil.TempFile` will
+	// create the file in the default location for our OS.
+	f, err := ioutil.TempFile("", "sample")
+	check(err)
+
+	// Display the name of the temporary file. On
+	// Unix-based OSes the directory will likely be `/tmp`.
+	// The file name starts with the prefix given as the
+	// second argument to `ioutil.TempFile` and the rest
+	// is chosen automatically to ensure that concurrent
+	// calls will always create different file names.
+	fmt.Println("Temp file name:", f.Name())
+
+	// Clean up the file after we're done. The OS is
+	// likely to clean up temporary files by itself after
+	// some time, but it's good practice to do this
+	// explicitly.
+	defer os.Remove(f.Name())
+
+	// We can write some data to the file.
+	_, err = f.Write([]byte{1, 2, 3, 4})
+	check(err)
+
+	// If we intend to write many temporary files, we may
+	// prefer to create a temporary *directory*.
+	// `ioutil.TempDir`'s arguments are the same as
+	// `TempFile`'s, but it returns a directory *name*
+	// rather than an open file.
+	dname, err := ioutil.TempDir("", "sampledir")
+	fmt.Println("Temp dir name:", dname)
+
+	defer os.RemoveAll(dname)
+
+	// Now we can synthesize temporary file names by
+	// prefixing them with our temporary directory.
+	fname := filepath.Join(dname, "file1")
+	err = ioutil.WriteFile(fname, []byte{1, 2}, 0666)
+	check(err)
+}

examples/temporary-files-and-directories/temporary-files-and-directories.hash

@@ -0,0 +1,2 @@
+5f7d0c43988d7dce235adb06ec02f4d2026b7f83
+pxE20wGTFjv

examples/temporary-files-and-directories/temporary-files-and-directories.sh

@@ -0,0 +1,3 @@
+$ go run temporary-files-and-directories.go
+Temp file name: /tmp/sample610887201
+Temp dir name: /tmp/sampledir898854668

examples/tickers/tickers.go

@@ -6,8 +6,10 @@
 
 package main
 
-import "time"
-import "fmt"
+import (
+	"fmt"
+	"time"
+)
 
 func main() {
 
@@ -16,10 +18,17 @@ func main() {
 	// `range` builtin on the channel to iterate over
 	// the values as they arrive every 500ms.
 	ticker := time.NewTicker(500 * time.Millisecond)
+	done := make(chan bool)
+
 	go func() {
-		for t := range ticker.C {
+		for {
+			select {
+			case <-done:
+				return
+			case t := <-ticker.C:
 				fmt.Println("Tick at", t)
 			}
+		}
 	}()
 
 	// Tickers can be stopped like timers. Once a ticker
@@ -27,5 +36,6 @@ func main() {
 	// channel. We'll stop ours after 1600ms.
 	time.Sleep(1600 * time.Millisecond)
 	ticker.Stop()
+	done <- true
 	fmt.Println("Ticker stopped")
 }

examples/tickers/tickers.hash

@@ -1,2 +1,2 @@
-7dc6447323f493f72aa70952bf3e3f2c6156f82f
-Rgc_UDvHv6a
+4a42333d14f902e890902343c7bd9b9c735fd8ad
+n1q1sSGEvmv

examples/time-formatting-parsing/time-formatting-parsing.go

@@ -3,8 +3,10 @@
 
 package main
 
-import "fmt"
-import "time"
+import (
+	"fmt"
+	"time"
+)
 
 func main() {
 	p := fmt.Println

examples/time-formatting-parsing/time-formatting-parsing.hash

@@ -1,2 +1,2 @@
-1f9962260f5c92efe57db0b96099b3dd06c90333
-nHAisH6amZG
+9e3f17061fef280191e3e8518365e231e17a5d5a
+1410R7Fcyx0

examples/time/time.go

@@ -3,8 +3,10 @@
 
 package main
 
-import "fmt"
-import "time"
+import (
+	"fmt"
+	"time"
+)
 
 func main() {
 	p := fmt.Println

examples/time/time.hash

@@ -1,2 +1,2 @@
-b6308f1fea7665e89a28f54aac6cb49b95685eb5
-PZMCzzaJURJ
+c47d853fa7527a652ce78b0285e452c6cd740050
+u-7i_p8BHVt

examples/timeouts/timeouts.go

@@ -5,14 +5,19 @@
 
 package main
 
-import "time"
-import "fmt"
+import (
+	"fmt"
+	"time"
+)
 
 func main() {
 
 	// For our example, suppose we're executing an external
 	// call that returns its result on a channel `c1`
-	// after 2s.
+	// after 2s. Note that the channel is buffered, so the
+	// send in the goroutine is nonblocking. This is a
+	// common pattern to prevent goroutine leaks in case the
+	// channel is never read.
 	c1 := make(chan string, 1)
 	go func() {
 		time.Sleep(2 * time.Second)

examples/timeouts/timeouts.hash

@@ -1,2 +1,2 @@
-93343e1aacb14f818c87732914c29ba57afab245
-MgcfA-xpJO9
+b8d3e745539b24d3530ca21efcdc924f08769edb
+TYJgoFjlTd6

examples/timeouts/timeouts.sh

@@ -3,9 +3,3 @@
 $ go run timeouts.go 
 timeout 1
 result 2
-
-# Using this `select` timeout pattern requires
-# communicating results over channels. This is a good
-# idea in general because other important Go features are
-# based on channels and `select`. We'll look at two
-# examples of this next: timers and tickers.

examples/timers/timers.go

@@ -6,8 +6,10 @@
 
 package main
 
-import "time"
-import "fmt"
+import (
+	"fmt"
+	"time"
+)
 
 func main() {
 

examples/timers/timers.hash

@@ -1,2 +1,2 @@
-e10c601ab3b702dfcea728c1edb31673561484b5
-pybl9hRvJq2
+e8e501d6083bea786629ca5e485e8b18caab4815
+pLnKEIesooU

examples/url-parsing/url-parsing.go

@@ -3,9 +3,11 @@
 
 package main
 
-import "fmt"
-import "net"
-import "net/url"
+import (
+	"fmt"
+	"net"
+	"net/url"
+)
 
 func main() {
 

examples/url-parsing/url-parsing.hash

@@ -1,2 +1,2 @@
-b7a0813e9413bfcc956cc58b850f655dd129ebb7
-AL79Lv-9CWo
+babc12f5066652f4cb0151231c06f1037298ff28
+M218D9Tldlr

examples/worker-pools/worker-pools.go

@@ -3,8 +3,10 @@
 
 package main
 
-import "fmt"
-import "time"
+import (
+	"fmt"
+	"time"
+)
 
 // Here's the worker, of which we'll run several
 // concurrent instances. These workers will receive

examples/worker-pools/worker-pools.hash

@@ -1,2 +1,2 @@
-bc69c6602d438413dcb9ceac112299ee253e4575
-yuHsGf712D1
+9b30cdfc3f46d634c3b8671a7ae1551c133fb6e2
+IiKZ-nj-nKY

examples/xml/xml.go

@@ -0,0 +1,69 @@
+// Go offers built-in support for XML and XML-like
+// formats with the `encoding.xml` package.
+
+package main
+
+import (
+	"encoding/xml"
+	"fmt"
+)
+
+// This type will be mapped to XML. Similarly to the
+// JSON examples, field tags contain directives for the
+// encoder and decoder. Here we use some special features
+// of the XML package: the `XMLName` field name dictates
+// the name of the XML element representing this struct;
+// `id,attr` means that the `Id` field is an XML
+// _attribute_ rather than a nested element.
+type Plant struct {
+	XMLName xml.Name `xml:"plant"`
+	Id      int      `xml:"id,attr"`
+	Name    string   `xml:"name"`
+	Origin  []string `xml:"origin"`
+}
+
+func (p Plant) String() string {
+	return fmt.Sprintf("Plant id=%v, name=%v, origin=%v",
+		p.Id, p.Name, p.Origin)
+}
+
+func main() {
+	coffee := &Plant{Id: 27, Name: "Coffee"}
+	coffee.Origin = []string{"Ethiopia", "Brazil"}
+
+	// Emit XML representing our plant; using
+	// `MarshalIndent` to produce a more
+	// human-readable output.
+	out, _ := xml.MarshalIndent(coffee, " ", "  ")
+	fmt.Println(string(out))
+
+	// To add a generic XML header to the output, append
+	// it explicitly.
+	fmt.Println(xml.Header + string(out))
+
+	// Use `Unmarhshal` to parse a stream of bytes with XML
+	// into a data structure. If the XML is malformed or
+	// cannot be mapped onto Plant, a descriptive error
+	// will be returned.
+	var p Plant
+	if err := xml.Unmarshal(out, &p); err != nil {
+		panic(err)
+	}
+	fmt.Println(p)
+
+	tomato := &Plant{Id: 81, Name: "Tomato"}
+	tomato.Origin = []string{"Mexico", "California"}
+
+	// The `parent>child>plant` field tag tells the encoder
+	// to nest all `plant`s under `<parent><child>...`
+	type Nesting struct {
+		XMLName xml.Name `xml:"nesting"`
+		Plants  []*Plant `xml:"parent>child>plant"`
+	}
+
+	nesting := &Nesting{}
+	nesting.Plants = []*Plant{coffee, tomato}
+
+	out, _ = xml.MarshalIndent(nesting, " ", "  ")
+	fmt.Println(string(out))
+}

examples/xml/xml.hash

@@ -0,0 +1,2 @@
+18ada773098bca38778a58b438d6af70529f18b0
+qd9Ii_3AW0s

examples/xml/xml.sh

@@ -0,0 +1,29 @@
+$ go run xml.go
+ <plant id="27">
+   <name>Coffee</name>
+   <origin>Ethiopia</origin>
+   <origin>Brazil</origin>
+ </plant>
+<?xml version="1.0" encoding="UTF-8"?>
+ <plant id="27">
+   <name>Coffee</name>
+   <origin>Ethiopia</origin>
+   <origin>Brazil</origin>
+ </plant>
+Plant id=27, name=Coffee, origin=[Ethiopia Brazil]
+ <nesting>
+   <parent>
+     <child>
+       <plant id="27">
+         <name>Coffee</name>
+         <origin>Ethiopia</origin>
+         <origin>Brazil</origin>
+       </plant>
+       <plant id="81">
+         <name>Tomato</name>
+         <origin>Mexico</origin>
+         <origin>California</origin>
+       </plant>
+     </child>
+   </parent>
+ </nesting>

public/arrays

@@ -5,6 +5,20 @@
     <title>Go by Example: Arrays</title>
     <link rel=stylesheet href="site.css">
   </head>
+  <script>
+      onkeydown = (e) => {
+          
+          if (e.key == "ArrowLeft") {
+              window.location.href = 'switch';
+          }
+          
+          
+          if (e.key == "ArrowRight") {
+              window.location.href = 'slices';
+          }
+          
+      }
+  </script>
   <body>
     <div class="example" id="arrays">
       <h2><a href="./">Go by Example</a>: Arrays</h2>
@@ -28,9 +42,7 @@ specific length.</p>
             
           </td>
           <td class="code leading">
-            <a href="http://play.golang.org/p/W7NwfDq8Vdw">
-              <img title="Run code" class="run" src="data:image/png;base64,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" />
-            </a>
+            <a href="http://play.golang.org/p/W7NwfDq8Vdw"><img title="Run code" src="play.png" class="run" /></a><img title="Copy code" src="clipboard.png" class="copy" />
           <div class="highlight"><pre><span class="kn">package</span> <span class="nx">main</span>
 </pre></div>
 
@@ -192,5 +204,10 @@ typical Go. We&rsquo;ll look at slices next.</p>
         by <a href="https://markmcgranaghan.com">Mark McGranaghan</a> | <a href="https://github.com/mmcgrana/gobyexample/blob/master/examples/arrays">source</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a>
       </p>
     </div>
+    <script>
+      var codeLines = [];
+      codeLines.push('');codeLines.push('package main\u000A');codeLines.push('import \"fmt\"\u000A');codeLines.push('func main() {\u000A');codeLines.push('    var a [5]int\u000A    fmt.Println(\"emp:\", a)\u000A');codeLines.push('    a[4] = 100\u000A    fmt.Println(\"set:\", a)\u000A    fmt.Println(\"get:\", a[4])\u000A');codeLines.push('    fmt.Println(\"len:\", len(a))\u000A');codeLines.push('    b := [5]int{1, 2, 3, 4, 5}\u000A    fmt.Println(\"dcl:\", b)\u000A');codeLines.push('    var twoD [2][3]int\u000A    for i := 0; i \x3C 2; i++ {\u000A        for j := 0; j \x3C 3; j++ {\u000A            twoD[i][j] = i + j\u000A        }\u000A    }\u000A    fmt.Println(\"2d: \", twoD)\u000A}\u000A');codeLines.push('');codeLines.push('');
+    </script>
+    <script src="site.js" async></script>
   </body>
 </html>

public/atomic-counters

@@ -5,6 +5,20 @@
     <title>Go by Example: Atomic Counters</title>
     <link rel=stylesheet href="site.css">
   </head>
+  <script>
+      onkeydown = (e) => {
+          
+          if (e.key == "ArrowLeft") {
+              window.location.href = 'rate-limiting';
+          }
+          
+          
+          if (e.key == "ArrowRight") {
+              window.location.href = 'mutexes';
+          }
+          
+      }
+  </script>
   <body>
     <div class="example" id="atomic-counters">
       <h2><a href="./">Go by Example</a>: Atomic Counters</h2>
@@ -32,9 +46,7 @@ counters</em> accessed by multiple goroutines.</p>
             
           </td>
           <td class="code leading">
-            <a href="http://play.golang.org/p/KDr9EMMPMgi">
-              <img title="Run code" class="run" src="data:image/png;base64,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" />
-            </a>
+            <a href="http://play.golang.org/p/F2pJfduyQiA"><img title="Run code" src="play.png" class="run" /></a><img title="Copy code" src="clipboard.png" class="copy" />
           <div class="highlight"><pre><span class="kn">package</span> <span class="nx">main</span>
 </pre></div>
 
@@ -47,9 +59,11 @@ counters</em> accessed by multiple goroutines.</p>
           </td>
           <td class="code leading">
             
-            <div class="highlight"><pre><span class="kn">import</span> <span class="s">&quot;fmt&quot;</span>
-<span class="kn">import</span> <span class="s">&quot;time&quot;</span>
-<span class="kn">import</span> <span class="s">&quot;sync/atomic&quot;</span>
+          <div class="highlight"><pre><span class="kn">import</span> <span class="p">(</span>
+    <span class="s">&quot;fmt&quot;</span>
+    <span class="s">&quot;sync&quot;</span>
+    <span class="s">&quot;sync/atomic&quot;</span>
+<span class="p">)</span>
 </pre></div>
 
           </td>
@@ -83,16 +97,28 @@ counters</em> accessed by multiple goroutines.</p>
         
         <tr>
           <td class="docs">
-            <p>To simulate concurrent updates, we&rsquo;ll start 50
-goroutines that each increment the counter about
-once a millisecond.</p>
+            <p>A WaitGroup will help us wait for all goroutines
+to finish their work.</p>
+
+          </td>
+          <td class="code leading">
+            
+          <div class="highlight"><pre>    <span class="kd">var</span> <span class="nx">wg</span> <span class="nx">sync</span><span class="p">.</span><span class="nx">WaitGroup</span>
+</pre></div>
+
+          </td>
+        </tr>
+        
+        <tr>
+          <td class="docs">
+            <p>We&rsquo;ll start 50 goroutines that each increment the
+counter exactly 1000 times.</p>
 
           </td>
           <td class="code leading">
             
           <div class="highlight"><pre>    <span class="k">for</span> <span class="nx">i</span> <span class="o">:=</span> <span class="mi">0</span><span class="p">;</span> <span class="nx">i</span> <span class="p">&lt;</span> <span class="mi">50</span><span class="p">;</span> <span class="nx">i</span><span class="o">++</span> <span class="p">{</span>
-        <span class="k">go</span> <span class="kd">func</span><span class="p">()</span> <span class="p">{</span>
-            <span class="k">for</span> <span class="p">{</span>
+        <span class="nx">wg</span><span class="p">.</span><span class="nx">Add</span><span class="p">(</span><span class="mi">1</span><span class="p">)</span>
 </pre></div>
 
           </td>
@@ -108,7 +134,8 @@ address of our <code>ops</code> counter with the
           </td>
           <td class="code leading">
             
-            <div class="highlight"><pre>                <span class="nx">atomic</span><span class="p">.</span><span class="nx">AddUint64</span><span class="p">(</span><span class="o">&amp;</span><span class="nx">ops</span><span class="p">,</span> <span class="mi">1</span><span class="p">)</span>
+          <div class="highlight"><pre>        <span class="k">go</span> <span class="kd">func</span><span class="p">()</span> <span class="p">{</span>
+            <span class="k">for</span> <span class="nx">c</span> <span class="o">:=</span> <span class="mi">0</span><span class="p">;</span> <span class="nx">c</span> <span class="p">&lt;</span> <span class="mi">1000</span><span class="p">;</span> <span class="nx">c</span><span class="o">++</span> <span class="p">{</span>
 </pre></div>
 
           </td>
@@ -116,13 +143,13 @@ address of our <code>ops</code> counter with the
         
         <tr>
           <td class="docs">
-            <p>Wait a bit between increments.</p>
             
           </td>
           <td class="code leading">
             
-            <div class="highlight"><pre>                <span class="nx">time</span><span class="p">.</span><span class="nx">Sleep</span><span class="p">(</span><span class="nx">time</span><span class="p">.</span><span class="nx">Millisecond</span><span class="p">)</span>
+          <div class="highlight"><pre>                <span class="nx">atomic</span><span class="p">.</span><span class="nx">AddUint64</span><span class="p">(</span><span class="o">&amp;</span><span class="nx">ops</span><span class="p">,</span> <span class="mi">1</span><span class="p">)</span>
             <span class="p">}</span>
+            <span class="nx">wg</span><span class="p">.</span><span class="nx">Done</span><span class="p">()</span>
         <span class="p">}()</span>
     <span class="p">}</span>
 </pre></div>
@@ -132,12 +159,12 @@ address of our <code>ops</code> counter with the
         
         <tr>
           <td class="docs">
-            <p>Wait a second to allow some ops to accumulate.</p>
+            <p>Wait until all the goroutines are done.</p>
 
           </td>
           <td class="code leading">
             
-            <div class="highlight"><pre>    <span class="nx">time</span><span class="p">.</span><span class="nx">Sleep</span><span class="p">(</span><span class="nx">time</span><span class="p">.</span><span class="nx">Second</span><span class="p">)</span>
+          <div class="highlight"><pre>    <span class="nx">wg</span><span class="p">.</span><span class="nx">Wait</span><span class="p">()</span>
 </pre></div>
 
           </td>
@@ -145,18 +172,16 @@ address of our <code>ops</code> counter with the
         
         <tr>
           <td class="docs">
-            <p>In order to safely use the counter while it&rsquo;s still
-being updated by other goroutines, we extract a
-copy of the current value into <code>opsFinal</code> via
-<code>LoadUint64</code>. As above we need to give this
-function the memory address <code>&amp;ops</code> from which to
-fetch the value.</p>
+            <p>It&rsquo;s safe to access <code>ops</code> now because we know
+no other goroutine is writing to it. Reading
+atomics safely while they are being updated is
+also possible, using functions like
+<code>atomic.LoadUint64</code>.</p>
 
           </td>
           <td class="code">
             
-            <div class="highlight"><pre>    <span class="nx">opsFinal</span> <span class="o">:=</span> <span class="nx">atomic</span><span class="p">.</span><span class="nx">LoadUint64</span><span class="p">(</span><span class="o">&amp;</span><span class="nx">ops</span><span class="p">)</span>
-    <span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="s">&quot;ops:&quot;</span><span class="p">,</span> <span class="nx">opsFinal</span><span class="p">)</span>
+          <div class="highlight"><pre>    <span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="s">&quot;ops:&quot;</span><span class="p">,</span> <span class="nx">ops</span><span class="p">)</span>
 <span class="p">}</span>
 </pre></div>
 
@@ -169,14 +194,18 @@ fetch the value.</p>
         
         <tr>
           <td class="docs">
-            <p>Running the program shows that we executed about
-40,000 operations.</p>
+            <p>We expect to get exactly 50,000 operations. Had we
+used the non-atomic <code>ops++</code> to increment the counter,
+we&rsquo;d likely get a different number, changing between
+runs, because the goroutines would interfere with
+each other. Moreover, we&rsquo;d get data race failures
+when running with the <code>-race</code> flag.</p>
 
           </td>
           <td class="code leading">
             
           <div class="highlight"><pre><span class="gp">$</span> go run atomic-counters.go
-<span class="go">ops: 41419</span>
+<span class="go">ops: 50000</span>
 </pre></div>
 
           </td>
@@ -205,5 +234,10 @@ state.</p>
         by <a href="https://markmcgranaghan.com">Mark McGranaghan</a> | <a href="https://github.com/mmcgrana/gobyexample/blob/master/examples/atomic-counters">source</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a>
       </p>
     </div>
+    <script>
+      var codeLines = [];
+      codeLines.push('');codeLines.push('package main\u000A');codeLines.push('import (\u000A    \"fmt\"\u000A    \"sync\"\u000A    \"sync/atomic\"\u000A)\u000A');codeLines.push('func main() {\u000A');codeLines.push('    var ops uint64\u000A');codeLines.push('    var wg sync.WaitGroup\u000A');codeLines.push('    for i := 0; i \x3C 50; i++ {\u000A        wg.Add(1)\u000A');codeLines.push('        go func() {\u000A            for c := 0; c \x3C 1000; c++ {\u000A');codeLines.push('                atomic.AddUint64(&ops, 1)\u000A            }\u000A            wg.Done()\u000A        }()\u000A    }\u000A');codeLines.push('    wg.Wait()\u000A');codeLines.push('    fmt.Println(\"ops:\", ops)\u000A}\u000A');codeLines.push('');codeLines.push('');
+    </script>
+    <script src="site.js" async></script>
   </body>
 </html>

public/base64-encoding

@@ -5,6 +5,20 @@
     <title>Go by Example: Base64 Encoding</title>
     <link rel=stylesheet href="site.css">
   </head>
+  <script>
+      onkeydown = (e) => {
+          
+          if (e.key == "ArrowLeft") {
+              window.location.href = 'sha1-hashes';
+          }
+          
+          
+          if (e.key == "ArrowRight") {
+              window.location.href = 'reading-files';
+          }
+          
+      }
+  </script>
   <body>
     <div class="example" id="base64-encoding">
       <h2><a href="./">Go by Example</a>: Base64 Encoding</h2>
@@ -28,9 +42,7 @@ encoding/decoding</a>.</p>
             
           </td>
           <td class="code leading">
-            <a href="http://play.golang.org/p/y_QTcqdkvZh">
-              <img title="Run code" class="run" src="data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAABAAAAAPCAYAAADtc08vAAAABGdBTUEAANbY1E9YMgAAABl0RVh0U29mdHdhcmUAQWRvYmUgSW1hZ2VSZWFkeXHJZTwAAAJ1SURBVCjPY/j//z8DMu7o6GAAgpQgD9tLqcmJH4KDg14aaik/MtdXe2ZjY6OCrh6Fs2jRYmZ9Pd05M9uL/u9dPfU/CLS0dfxvKIz/X5Dg/z8pKdkGqwGpqakMUdExDHJSYqt37tjxf+qUSf9rc2P+79298/+RA3v+H1zV///o6r7/DrbWFQkJiQwxMTGoBjAxMTpKiQmuqMuP/f/xw/v/J0+f/W9tbvTfxVLn/8rJVf+v757z/96hRf8TQtxuCQmLMjk4OKAawMfDVWVvrvd85eTq/7tXTP6/e/XM/22lif9LCnL+b13Q/v/Kzln/L++c/X/7/Jb/VpYWuZFRUagGAAErEBtlxvi+vn944f9L26cDNcz6v21R9/8zm6aC2SBDbu+f/78kK+4/L79AO7oBYCAqxD/57JZp/y/tmPX/wrYZ/6+CbAayD6zs/78daBjIgPayFJAGG6wGAIFAcpjH/dv7F4ANABuya/b/Od3l/ye2V/+/tnv2/7ldxSANmrgMYGBhZg7fuagD7GyYIeeBrrqwdRrQgLn/l02sBGkwwWkAEAjV5EZ/vQV0LswAGAYZsLC3DKTBAJ8BzCkRni/uHFyIYcAtoNc6ypL/ANVIohigrKwMxqqqqgxMzKzM6VHeL+6iGQAKzDtAV5XlJv3n5uFLRTHgzZs3YPzz50+GwqJiPitD9Y8Pjy4BB+CNvfP+3wUmIpAhhckhr3X19LodHZ28UQxQU1MDYw0NDQYBAQEeoBOTK7JjP2xf3Pt/bkfB/4KkoDcKMmIL5OXlFerq6hhu3rzJgC8MwMDYxGSfm5vbVn9/f0cgVxAkpqioyFBfX49iAACbTAK+xT3CzgAAAABJRU5ErkJggg==" />
-            </a>
+            <a href="http://play.golang.org/p/V3oV1bvh94k"><img title="Run code" src="play.png" class="run" /></a><img title="Copy code" src="clipboard.png" class="copy" />
           <div class="highlight"><pre><span class="kn">package</span> <span class="nx">main</span>
 </pre></div>
 
@@ -46,8 +58,10 @@ save us some space below.</p>
           </td>
           <td class="code leading">
             
-            <div class="highlight"><pre><span class="kn">import</span> <span class="nx">b64</span> <span class="s">&quot;encoding/base64&quot;</span>
-<span class="kn">import</span> <span class="s">&quot;fmt&quot;</span>
+          <div class="highlight"><pre><span class="kn">import</span> <span class="p">(</span>
+    <span class="nx">b64</span> <span class="s">&quot;encoding/base64&quot;</span>
+    <span class="s">&quot;fmt&quot;</span>
+<span class="p">)</span>
 </pre></div>
 
           </td>
@@ -175,5 +189,10 @@ but they both decode to the original string as desired.</p>
         by <a href="https://markmcgranaghan.com">Mark McGranaghan</a> | <a href="https://github.com/mmcgrana/gobyexample/blob/master/examples/base64-encoding">source</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a>
       </p>
     </div>
+    <script>
+      var codeLines = [];
+      codeLines.push('');codeLines.push('package main\u000A');codeLines.push('import (\u000A    b64 \"encoding/base64\"\u000A    \"fmt\"\u000A)\u000A');codeLines.push('func main() {\u000A');codeLines.push('    data := \"abc123!?$*&()\'-=@~\"\u000A');codeLines.push('    sEnc := b64.StdEncoding.EncodeToString([]byte(data))\u000A    fmt.Println(sEnc)\u000A');codeLines.push('    sDec, _ := b64.StdEncoding.DecodeString(sEnc)\u000A    fmt.Println(string(sDec))\u000A    fmt.Println()\u000A');codeLines.push('    uEnc := b64.URLEncoding.EncodeToString([]byte(data))\u000A    fmt.Println(uEnc)\u000A    uDec, _ := b64.URLEncoding.DecodeString(uEnc)\u000A    fmt.Println(string(uDec))\u000A}\u000A');codeLines.push('');codeLines.push('');
+    </script>
+    <script src="site.js" async></script>
   </body>
 </html>

public/channel-buffering

@@ -5,6 +5,20 @@
     <title>Go by Example: Channel Buffering</title>
     <link rel=stylesheet href="site.css">
   </head>
+  <script>
+      onkeydown = (e) => {
+          
+          if (e.key == "ArrowLeft") {
+              window.location.href = 'channels';
+          }
+          
+          
+          if (e.key == "ArrowRight") {
+              window.location.href = 'channel-synchronization';
+          }
+          
+      }
+  </script>
   <body>
     <div class="example" id="channel-buffering">
       <h2><a href="./">Go by Example</a>: Channel Buffering</h2>
@@ -32,9 +46,7 @@ those values.</p>
             
           </td>
           <td class="code leading">
-            <a href="http://play.golang.org/p/mPoF-Xi-rip">
-              <img title="Run code" class="run" src="data:image/png;base64,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" />
-            </a>
+            <a href="http://play.golang.org/p/mPoF-Xi-rip"><img title="Run code" src="play.png" class="run" /></a><img title="Copy code" src="clipboard.png" class="copy" />
           <div class="highlight"><pre><span class="kn">package</span> <span class="nx">main</span>
 </pre></div>
 
@@ -139,5 +151,10 @@ concurrent receive.</p>
         by <a href="https://markmcgranaghan.com">Mark McGranaghan</a> | <a href="https://github.com/mmcgrana/gobyexample/blob/master/examples/channel-buffering">source</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a>
       </p>
     </div>
+    <script>
+      var codeLines = [];
+      codeLines.push('');codeLines.push('package main\u000A');codeLines.push('import \"fmt\"\u000A');codeLines.push('func main() {\u000A');codeLines.push('    messages := make(chan string, 2)\u000A');codeLines.push('    messages \x3C- \"buffered\"\u000A    messages \x3C- \"channel\"\u000A');codeLines.push('    fmt.Println(\x3C-messages)\u000A    fmt.Println(\x3C-messages)\u000A}\u000A');codeLines.push('');
+    </script>
+    <script src="site.js" async></script>
   </body>
 </html>

public/channel-directions

@@ -5,6 +5,20 @@
     <title>Go by Example: Channel Directions</title>
     <link rel=stylesheet href="site.css">
   </head>
+  <script>
+      onkeydown = (e) => {
+          
+          if (e.key == "ArrowLeft") {
+              window.location.href = 'channel-synchronization';
+          }
+          
+          
+          if (e.key == "ArrowRight") {
+              window.location.href = 'select';
+          }
+          
+      }
+  </script>
   <body>
     <div class="example" id="channel-directions">
       <h2><a href="./">Go by Example</a>: Channel Directions</h2>
@@ -30,9 +44,7 @@ the program.</p>
             
           </td>
           <td class="code leading">
-            <a href="http://play.golang.org/p/Jnn9_9hC48c">
-              <img title="Run code" class="run" src="data:image/png;base64,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" />
-            </a>
+            <a href="http://play.golang.org/p/Jnn9_9hC48c"><img title="Run code" src="play.png" class="run" /></a><img title="Copy code" src="clipboard.png" class="copy" />
           <div class="highlight"><pre><span class="kn">package</span> <span class="nx">main</span>
 </pre></div>
 
@@ -131,5 +143,10 @@ receive on this channel.</p>
         by <a href="https://markmcgranaghan.com">Mark McGranaghan</a> | <a href="https://github.com/mmcgrana/gobyexample/blob/master/examples/channel-directions">source</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a>
       </p>
     </div>
+    <script>
+      var codeLines = [];
+      codeLines.push('');codeLines.push('package main\u000A');codeLines.push('import \"fmt\"\u000A');codeLines.push('func ping(pings chan\x3C- string, msg string) {\u000A    pings \x3C- msg\u000A}\u000A');codeLines.push('func pong(pings \x3C-chan string, pongs chan\x3C- string) {\u000A    msg := \x3C-pings\u000A    pongs \x3C- msg\u000A}\u000A');codeLines.push('func main() {\u000A    pings := make(chan string, 1)\u000A    pongs := make(chan string, 1)\u000A    ping(pings, \"passed message\")\u000A    pong(pings, pongs)\u000A    fmt.Println(\x3C-pongs)\u000A}\u000A');codeLines.push('');
+    </script>
+    <script src="site.js" async></script>
   </body>
 </html>

public/channel-synchronization

@@ -5,6 +5,20 @@
     <title>Go by Example: Channel Synchronization</title>
     <link rel=stylesheet href="site.css">
   </head>
+  <script>
+      onkeydown = (e) => {
+          
+          if (e.key == "ArrowLeft") {
+              window.location.href = 'channel-buffering';
+          }
+          
+          
+          if (e.key == "ArrowRight") {
+              window.location.href = 'channel-directions';
+          }
+          
+      }
+  </script>
   <body>
     <div class="example" id="channel-synchronization">
       <h2><a href="./">Go by Example</a>: Channel Synchronization</h2>
@@ -31,9 +45,7 @@ you may prefer to use a <a href="waitgroups">WaitGroup</a>.</p>
             
           </td>
           <td class="code leading">
-            <a href="http://play.golang.org/p/8lmP8beav0p">
-              <img title="Run code" class="run" src="data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAABAAAAAPCAYAAADtc08vAAAABGdBTUEAANbY1E9YMgAAABl0RVh0U29mdHdhcmUAQWRvYmUgSW1hZ2VSZWFkeXHJZTwAAAJ1SURBVCjPY/j//z8DMu7o6GAAgpQgD9tLqcmJH4KDg14aaik/MtdXe2ZjY6OCrh6Fs2jRYmZ9Pd05M9uL/u9dPfU/CLS0dfxvKIz/X5Dg/z8pKdkGqwGpqakMUdExDHJSYqt37tjxf+qUSf9rc2P+79298/+RA3v+H1zV///o6r7/DrbWFQkJiQwxMTGoBjAxMTpKiQmuqMuP/f/xw/v/J0+f/W9tbvTfxVLn/8rJVf+v757z/96hRf8TQtxuCQmLMjk4OKAawMfDVWVvrvd85eTq/7tXTP6/e/XM/22lif9LCnL+b13Q/v/Kzln/L++c/X/7/Jb/VpYWuZFRUagGAAErEBtlxvi+vn944f9L26cDNcz6v21R9/8zm6aC2SBDbu+f/78kK+4/L79AO7oBYCAqxD/57JZp/y/tmPX/wrYZ/6+CbAayD6zs/78daBjIgPayFJAGG6wGAIFAcpjH/dv7F4ANABuya/b/Od3l/ye2V/+/tnv2/7ldxSANmrgMYGBhZg7fuagD7GyYIeeBrrqwdRrQgLn/l02sBGkwwWkAEAjV5EZ/vQV0LswAGAYZsLC3DKTBAJ8BzCkRni/uHFyIYcAtoNc6ypL/ANVIohigrKwMxqqqqgxMzKzM6VHeL+6iGQAKzDtAV5XlJv3n5uFLRTHgzZs3YPzz50+GwqJiPitD9Y8Pjy4BB+CNvfP+3wUmIpAhhckhr3X19LodHZ28UQxQU1MDYw0NDQYBAQEeoBOTK7JjP2xf3Pt/bkfB/4KkoDcKMmIL5OXlFerq6hhu3rzJgC8MwMDYxGSfm5vbVn9/f0cgVxAkpqioyFBfX49iAACbTAK+xT3CzgAAAABJRU5ErkJggg==" />
-            </a>
+            <a href="http://play.golang.org/p/fe9If6OhYMk"><img title="Run code" src="play.png" class="run" /></a><img title="Copy code" src="clipboard.png" class="copy" />
           <div class="highlight"><pre><span class="kn">package</span> <span class="nx">main</span>
 </pre></div>
 
@@ -46,8 +58,10 @@ you may prefer to use a <a href="waitgroups">WaitGroup</a>.</p>
           </td>
           <td class="code leading">
             
-            <div class="highlight"><pre><span class="kn">import</span> <span class="s">&quot;fmt&quot;</span>
-<span class="kn">import</span> <span class="s">&quot;time&quot;</span>
+          <div class="highlight"><pre><span class="kn">import</span> <span class="p">(</span>
+    <span class="s">&quot;fmt&quot;</span>
+    <span class="s">&quot;time&quot;</span>
+<span class="p">)</span>
 </pre></div>
 
           </td>
@@ -168,5 +182,10 @@ started.</p>
         by <a href="https://markmcgranaghan.com">Mark McGranaghan</a> | <a href="https://github.com/mmcgrana/gobyexample/blob/master/examples/channel-synchronization">source</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a>
       </p>
     </div>
+    <script>
+      var codeLines = [];
+      codeLines.push('');codeLines.push('package main\u000A');codeLines.push('import (\u000A    \"fmt\"\u000A    \"time\"\u000A)\u000A');codeLines.push('func worker(done chan bool) {\u000A    fmt.Print(\"working...\")\u000A    time.Sleep(time.Second)\u000A    fmt.Println(\"done\")\u000A');codeLines.push('    done \x3C- true\u000A}\u000A');codeLines.push('func main() {\u000A');codeLines.push('    done := make(chan bool, 1)\u000A    go worker(done)\u000A');codeLines.push('    \x3C-done\u000A}\u000A');codeLines.push('');codeLines.push('');
+    </script>
+    <script src="site.js" async></script>
   </body>
 </html>

public/channels

@@ -5,6 +5,20 @@
     <title>Go by Example: Channels</title>
     <link rel=stylesheet href="site.css">
   </head>
+  <script>
+      onkeydown = (e) => {
+          
+          if (e.key == "ArrowLeft") {
+              window.location.href = 'goroutines';
+          }
+          
+          
+          if (e.key == "ArrowRight") {
+              window.location.href = 'channel-buffering';
+          }
+          
+      }
+  </script>
   <body>
     <div class="example" id="channels">
       <h2><a href="./">Go by Example</a>: Channels</h2>
@@ -30,9 +44,7 @@ goroutine.</p>
             
           </td>
           <td class="code leading">
-            <a href="http://play.golang.org/p/bRGMAqinovA">
-              <img title="Run code" class="run" src="data:image/png;base64,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" />
-            </a>
+            <a href="http://play.golang.org/p/bRGMAqinovA"><img title="Run code" src="play.png" class="run" /></a><img title="Copy code" src="clipboard.png" class="copy" />
           <div class="highlight"><pre><span class="kn">package</span> <span class="nx">main</span>
 </pre></div>
 
@@ -154,5 +166,10 @@ message without having to use any other synchronization.</p>
         by <a href="https://markmcgranaghan.com">Mark McGranaghan</a> | <a href="https://github.com/mmcgrana/gobyexample/blob/master/examples/channels">source</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a>
       </p>
     </div>
+    <script>
+      var codeLines = [];
+      codeLines.push('');codeLines.push('package main\u000A');codeLines.push('import \"fmt\"\u000A');codeLines.push('func main() {\u000A');codeLines.push('    messages := make(chan string)\u000A');codeLines.push('    go func() { messages \x3C- \"ping\" }()\u000A');codeLines.push('    msg := \x3C-messages\u000A    fmt.Println(msg)\u000A}\u000A');codeLines.push('');codeLines.push('');
+    </script>
+    <script src="site.js" async></script>
   </body>
 </html>

public/closing-channels

@@ -5,6 +5,20 @@
     <title>Go by Example: Closing Channels</title>
     <link rel=stylesheet href="site.css">
   </head>
+  <script>
+      onkeydown = (e) => {
+          
+          if (e.key == "ArrowLeft") {
+              window.location.href = 'non-blocking-channel-operations';
+          }
+          
+          
+          if (e.key == "ArrowRight") {
+              window.location.href = 'range-over-channels';
+          }
+          
+      }
+  </script>
   <body>
     <div class="example" id="closing-channels">
       <h2><a href="./">Go by Example</a>: Closing Channels</h2>
@@ -29,9 +43,7 @@ completion to the channel&rsquo;s receivers.</p>
             
           </td>
           <td class="code leading">
-            <a href="http://play.golang.org/p/mkz69rVMHs6">
-              <img title="Run code" class="run" src="data:image/png;base64,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" />
-            </a>
+            <a href="http://play.golang.org/p/mkz69rVMHs6"><img title="Run code" src="play.png" class="run" /></a><img title="Copy code" src="clipboard.png" class="copy" />
           <div class="highlight"><pre><span class="kn">package</span> <span class="nx">main</span>
 </pre></div>
 
@@ -180,5 +192,10 @@ example: <code>range</code> over channels.</p>
         by <a href="https://markmcgranaghan.com">Mark McGranaghan</a> | <a href="https://github.com/mmcgrana/gobyexample/blob/master/examples/closing-channels">source</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a>
       </p>
     </div>
+    <script>
+      var codeLines = [];
+      codeLines.push('');codeLines.push('package main\u000A');codeLines.push('import \"fmt\"\u000A');codeLines.push('func main() {\u000A    jobs := make(chan int, 5)\u000A    done := make(chan bool)\u000A');codeLines.push('    go func() {\u000A        for {\u000A            j, more := \x3C-jobs\u000A            if more {\u000A                fmt.Println(\"received job\", j)\u000A            } else {\u000A                fmt.Println(\"received all jobs\")\u000A                done \x3C- true\u000A                return\u000A            }\u000A        }\u000A    }()\u000A');codeLines.push('    for j := 1; j \x3C= 3; j++ {\u000A        jobs \x3C- j\u000A        fmt.Println(\"sent job\", j)\u000A    }\u000A    close(jobs)\u000A    fmt.Println(\"sent all jobs\")\u000A');codeLines.push('    \x3C-done\u000A}\u000A');codeLines.push('');codeLines.push('');
+    </script>
+    <script src="site.js" async></script>
   </body>
 </html>