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Diffstat (limited to 'doc/go_tutorial.html')
| -rw-r--r-- | doc/go_tutorial.html | 351 |
1 files changed, 184 insertions, 167 deletions
diff --git a/doc/go_tutorial.html b/doc/go_tutorial.html index f3715f3bd..9576feee7 100644 --- a/doc/go_tutorial.html +++ b/doc/go_tutorial.html @@ -30,7 +30,7 @@ Let's start in the usual way: 07 import fmt "fmt" // Package implementing formatted I/O. <p> 09 func main() { -10 fmt.Printf("Hello, world; or Καλημέρα κόσμε; or こんにちは 世界\n"); +10 fmt.Printf("Hello, world; or Καλημέρα κόσμε; or こんにちは 世界\n") 11 } </pre> <p> @@ -55,6 +55,32 @@ The comment convention is the same as in C++: <p> Later we'll have much more to say about printing. <p> +<h2>Semicolons</h2> +<p> +You might have noticed that our program has no semicolons. In Go +code, the only place you typically see semicolons is separating the +clauses of <code>for</code> loops and the like; they are not necessary after +every statement. +<p> +In fact, what happens is that the formal language uses semicolons, +much as in C or Java, but they are inserted automatically +at the end of every line that looks like the end of a statement. You +don't need to type them yourself. +<p> +For details about how this is done you can see the language +specification, but in practice all you need to know is that you +never need to put a semicolon at the end of a line. (You can put +them in if you want to write multiple statements per line.) As an +extra help, you can also leave out a semicolon immediately before +a closing brace. +<p> +This approach makes for clean-looking, semicolon-free code. The +one surprise is that it's important to put the opening +brace of a construct such as an <code>if</code> statement on the same line as +the <code>if</code>; if you don't, there are situations that may not compile +or may give the wrong result. The language forces the brace style +to some extent. +<p> <h2>Compiling</h2> <p> Go is a compiled language. At the moment there are two compilers. @@ -92,30 +118,30 @@ Next up, here's a version of the Unix utility <code>echo(1)</code>: 05 package main <p> 07 import ( -08 "os"; -09 "flag"; // command line option parser +08 "os" +09 "flag" // command line option parser 10 ) <p> 12 var omitNewline = flag.Bool("n", false, "don't print final newline") <p> 14 const ( -15 Space = " "; -16 Newline = "\n"; +15 Space = " " +16 Newline = "\n" 17 ) <p> 19 func main() { -20 flag.Parse(); // Scans the arg list and sets up flags -21 var s string = ""; +20 flag.Parse() // Scans the arg list and sets up flags +21 var s string = "" 22 for i := 0; i < flag.NArg(); i++ { 23 if i > 0 { 24 s += Space 25 } -26 s += flag.Arg(i); +26 s += flag.Arg(i) 27 } 28 if !*omitNewline { 29 s += Newline 30 } -31 os.Stdout.WriteString(s); +31 os.Stdout.WriteString(s) 32 } </pre> <p> @@ -123,7 +149,7 @@ This program is small but it's doing a number of new things. In the last exampl we saw <code>func</code> introduce a function. The keywords <code>var</code>, <code>const</code>, and <code>type</code> (not used yet) also introduce declarations, as does <code>import</code>. Notice that we can group declarations of the same sort into -parenthesized, semicolon-separated lists if we want, as on lines 7-10 and 14-17. +parenthesized lists, one item per line, as on lines 7-10 and 14-17. But it's not necessary to do so; we could have said <p> <pre> @@ -131,21 +157,6 @@ But it's not necessary to do so; we could have said const Newline = "\n" </pre> <p> -Semicolons aren't needed here; in fact, semicolons are unnecessary after any -top-level declaration, although they are needed as separators <i>within</i> -a parenthesized list of declarations. -<p> -You can use semicolons just the way you would in C, C++, or Java, but if you -prefer you can also leave them out in many cases. They <i>separate</i> statements -rather than terminate them, so they aren't needed (but are still OK) at the end of the last -statement in a block. -They're also optional after braces, as in C. -Have a look at the source to <code>echo</code>. -The only necessary semicolons in that program are on lines 8, 15, and 21 -and of course between the elements of the <code>for</code> loop on line 22. -The ones on line 9, 16, 26, and 31 are optional but are there because a semicolon -on the end of a list of statements makes it easier to edit the list later. -<p> This program imports the <code>"os"</code> package to access its <code>Stdout</code> variable, of type <code>*os.File</code>. The <code>import</code> statement is actually a declaration: in its general form, as used in our ``hello world'' program, @@ -242,11 +253,11 @@ of course you can change a string <i>variable</i> simply by reassigning it. This snippet from <code>strings.go</code> is legal code: <p> <pre> <!-- progs/strings.go /hello/ /ciao/ --> -11 s := "hello"; +11 s := "hello" 12 if s[1] != 'e' { os.Exit(1) } -13 s = "good bye"; -14 var p *string = &s; -15 *p = "ciao"; +13 s = "good bye" +14 var p *string = &s +15 *p = "ciao" </pre> <p> However the following statements are illegal because they would modify @@ -302,7 +313,7 @@ Using slices one can write this function (from <code>sum.go</code>): <p> <pre> <!-- progs/sum.go /sum/ /^}/ --> 09 func sum(a []int) int { // returns an int -10 s := 0; +10 s := 0 11 for i := 0; i < len(a); i++ { 12 s += a[i] 13 } @@ -313,7 +324,7 @@ Using slices one can write this function (from <code>sum.go</code>): and invoke it like this: <p> <pre> <!-- progs/sum.go /1,2,3/ --> -19 s := sum(&[3]int{1,2,3}); // a slice of the array is passed to sum +19 s := sum(&[3]int{1,2,3}) // a slice of the array is passed to sum </pre> <p> Note how the return type (<code>int</code>) is defined for <code>sum()</code> by stating it @@ -454,13 +465,13 @@ sort of open/close/read/write interface. Here's the start of <code>file.go</cod 05 package file <p> 07 import ( -08 "os"; -09 "syscall"; +08 "os" +09 "syscall" 10 ) <p> 12 type File struct { -13 fd int; // file descriptor number -14 name string; // file name at Open time +13 fd int // file descriptor number +14 name string // file name at Open time 15 } </pre> <p> @@ -520,9 +531,9 @@ We can use the factory to construct some familiar, exported variables of type <c <p> <pre> <!-- progs/file.go /var/ /^.$/ --> 24 var ( -25 Stdin = newFile(0, "/dev/stdin"); -26 Stdout = newFile(1, "/dev/stdout"); -27 Stderr = newFile(2, "/dev/stderr"); +25 Stdin = newFile(0, "/dev/stdin") +26 Stdout = newFile(1, "/dev/stdout") +27 Stderr = newFile(2, "/dev/stderr") 28 ) </pre> <p> @@ -531,9 +542,9 @@ exported factory to use is <code>Open</code>: <p> <pre> <!-- progs/file.go /func.Open/ /^}/ --> 30 func Open(name string, mode int, perm int) (file *File, err os.Error) { -31 r, e := syscall.Open(name, mode, perm); +31 r, e := syscall.Open(name, mode, perm) 32 if e != 0 { -33 err = os.Errno(e); +33 err = os.Errno(e) 34 } 35 return newFile(r, name), err 36 } @@ -569,10 +580,10 @@ each of which declares a receiver variable <code>file</code>. 39 if file == nil { 40 return os.EINVAL 41 } -42 e := syscall.Close(file.fd); -43 file.fd = -1; // so it can't be closed again +42 e := syscall.Close(file.fd) +43 file.fd = -1 // so it can't be closed again 44 if e != 0 { -45 return os.Errno(e); +45 return os.Errno(e) 46 } 47 return nil 48 } @@ -581,9 +592,9 @@ each of which declares a receiver variable <code>file</code>. 51 if file == nil { 52 return -1, os.EINVAL 53 } -54 r, e := syscall.Read(file.fd, b); +54 r, e := syscall.Read(file.fd, b) 55 if e != 0 { -56 err = os.Errno(e); +56 err = os.Errno(e) 57 } 58 return int(r), err 59 } @@ -592,9 +603,9 @@ each of which declares a receiver variable <code>file</code>. 62 if file == nil { 63 return -1, os.EINVAL 64 } -65 r, e := syscall.Write(file.fd, b); +65 r, e := syscall.Write(file.fd, b) 66 if e != 0 { -67 err = os.Errno(e); +67 err = os.Errno(e) 68 } 69 return int(r), err 70 } @@ -623,18 +634,18 @@ We can now use our new package: 05 package main <p> 07 import ( -08 "./file"; -09 "fmt"; -10 "os"; +08 "./file" +09 "fmt" +10 "os" 11 ) <p> 13 func main() { -14 hello := []byte{'h', 'e', 'l', 'l', 'o', ',', ' ', 'w', 'o', 'r', 'l', 'd', '\n'}; -15 file.Stdout.Write(hello); -16 file, err := file.Open("/does/not/exist", 0, 0); +14 hello := []byte{'h', 'e', 'l', 'l', 'o', ',', ' ', 'w', 'o', 'r', 'l', 'd', '\n'} +15 file.Stdout.Write(hello) +16 file, err := file.Open("/does/not/exist", 0, 0) 17 if file == nil { -18 fmt.Printf("can't open file; err=%s\n", err.String()); -19 os.Exit(1); +18 fmt.Printf("can't open file; err=%s\n", err.String()) +19 os.Exit(1) 20 } 21 } </pre> @@ -660,43 +671,43 @@ Building on the <code>file</code> package, here's a simple version of the Unix u 05 package main <p> 07 import ( -08 "./file"; -09 "flag"; -10 "fmt"; -11 "os"; +08 "./file" +09 "flag" +10 "fmt" +11 "os" 12 ) <p> 14 func cat(f *file.File) { -15 const NBUF = 512; -16 var buf [NBUF]byte; +15 const NBUF = 512 +16 var buf [NBUF]byte 17 for { 18 switch nr, er := f.Read(&buf); true { 19 case nr < 0: -20 fmt.Fprintf(os.Stderr, "cat: error reading from %s: %s\n", f.String(), er.String()); -21 os.Exit(1); +20 fmt.Fprintf(os.Stderr, "cat: error reading from %s: %s\n", f.String(), er.String()) +21 os.Exit(1) 22 case nr == 0: // EOF -23 return; +23 return 24 case nr > 0: 25 if nw, ew := file.Stdout.Write(buf[0:nr]); nw != nr { -26 fmt.Fprintf(os.Stderr, "cat: error writing from %s: %s\n", f.String(), ew.String()); +26 fmt.Fprintf(os.Stderr, "cat: error writing from %s: %s\n", f.String(), ew.String()) 27 } 28 } 29 } 30 } <p> 32 func main() { -33 flag.Parse(); // Scans the arg list and sets up flags +33 flag.Parse() // Scans the arg list and sets up flags 34 if flag.NArg() == 0 { -35 cat(file.Stdin); +35 cat(file.Stdin) 36 } 37 for i := 0; i < flag.NArg(); i++ { -38 f, err := file.Open(flag.Arg(i), 0, 0); +38 f, err := file.Open(flag.Arg(i), 0, 0) 39 if f == nil { -40 fmt.Fprintf(os.Stderr, "cat: can't open %s: error %s\n", flag.Arg(i), err); -41 os.Exit(1); +40 fmt.Fprintf(os.Stderr, "cat: can't open %s: error %s\n", flag.Arg(i), err) +41 os.Exit(1) 42 } -43 cat(f); -44 f.Close(); +43 cat(f) +44 f.Close() 45 } 46 } </pre> @@ -729,8 +740,8 @@ Here is code from <code>progs/cat_rot13.go</code>: <p> <pre> <!-- progs/cat_rot13.go /type.reader/ /^}/ --> 26 type reader interface { -27 Read(b []byte) (ret int, err os.Error); -28 String() string; +27 Read(b []byte) (ret int, err os.Error) +28 String() string 29 } </pre> <p> @@ -746,7 +757,7 @@ we have a second implementation of the <code>reader</code> interface. <p> <pre> <!-- progs/cat_rot13.go /type.rotate13/ /end.of.rotate13/ --> 31 type rotate13 struct { -32 source reader; +32 source reader 33 } <p> 35 func newRotate13(source reader) *rotate13 { @@ -754,7 +765,7 @@ we have a second implementation of the <code>reader</code> interface. 37 } <p> 39 func (r13 *rotate13) Read(b []byte) (ret int, err os.Error) { -40 r, e := r13.source.Read(b); +40 r, e := r13.source.Read(b) 41 for i := 0; i < r; i++ { 42 b[i] = rot13(b[i]) 43 } @@ -779,8 +790,8 @@ and use it from within a mostly unchanged <code>cat()</code> function: <p> <pre> <!-- progs/cat_rot13.go /func.cat/ /^}/ --> 52 func cat(r reader) { -53 const NBUF = 512; -54 var buf [NBUF]byte; +53 const NBUF = 512 +54 var buf [NBUF]byte <p> 56 if *rot13Flag { 57 r = newRotate13(r) @@ -788,14 +799,14 @@ and use it from within a mostly unchanged <code>cat()</code> function: 59 for { 60 switch nr, er := r.Read(&buf); { 61 case nr < 0: -62 fmt.Fprintf(os.Stderr, "cat: error reading from %s: %s\n", r.String(), er.String()); -63 os.Exit(1); +62 fmt.Fprintf(os.Stderr, "cat: error reading from %s: %s\n", r.String(), er.String()) +63 os.Exit(1) 64 case nr == 0: // EOF -65 return; +65 return 66 case nr > 0: -67 nw, ew := file.Stdout.Write(buf[0:nr]); +67 nw, ew := file.Stdout.Write(buf[0:nr]) 68 if nw != nr { -69 fmt.Fprintf(os.Stderr, "cat: error writing from %s: %s\n", r.String(), ew.String()); +69 fmt.Fprintf(os.Stderr, "cat: error writing from %s: %s\n", r.String(), ew.String()) 70 } 71 } 72 } @@ -851,7 +862,7 @@ As an example, consider this simple sort algorithm taken from <code>progs/sort.g 13 func Sort(data Interface) { 14 for i := 1; i < data.Len(); i++ { 15 for j := i; j > 0 && data.Less(j, j-1); j-- { -16 data.Swap(j, j-1); +16 data.Swap(j, j-1) 17 } 18 } 19 } @@ -861,9 +872,9 @@ The code needs only three methods, which we wrap into sort's <code>Interface</co <p> <pre> <!-- progs/sort.go /interface/ /^}/ --> 07 type Interface interface { -08 Len() int; -09 Less(i, j int) bool; -10 Swap(i, j int); +08 Len() int +09 Less(i, j int) bool +10 Swap(i, j int) 11 } </pre> <p> @@ -874,9 +885,9 @@ arrays of integers, strings, etc.; here's the code for arrays of <code>int</code <pre> <!-- progs/sort.go /type.*IntArray/ /Swap/ --> 33 type IntArray []int <p> -35 func (p IntArray) Len() int { return len(p); } -36 func (p IntArray) Less(i, j int) bool { return p[i] < p[j]; } -37 func (p IntArray) Swap(i, j int) { p[i], p[j] = p[j], p[i]; } +35 func (p IntArray) Len() int { return len(p) } +36 func (p IntArray) Less(i, j int) bool { return p[i] < p[j] } +37 func (p IntArray) Swap(i, j int) { p[i], p[j] = p[j], p[i] } </pre> <p> Here we see methods defined for non-<code>struct</code> types. You can define methods @@ -888,9 +899,9 @@ to test that the result is sorted. <p> <pre> <!-- progs/sortmain.go /func.ints/ /^}/ --> 12 func ints() { -13 data := []int{74, 59, 238, -784, 9845, 959, 905, 0, 0, 42, 7586, -5467984, 7586}; -14 a := sort.IntArray(data); -15 sort.Sort(a); +13 data := []int{74, 59, 238, -784, 9845, 959, 905, 0, 0, 42, 7586, -5467984, 7586} +14 a := sort.IntArray(data) +15 sort.Sort(a) 16 if !sort.IsSorted(a) { 17 panic() 18 } @@ -902,18 +913,18 @@ to implement the three methods for that type, like this: <p> <pre> <!-- progs/sortmain.go /type.day/ /Swap/ --> 30 type day struct { -31 num int; -32 shortName string; -33 longName string; +31 num int +32 shortName string +33 longName string 34 } <p> 36 type dayArray struct { -37 data []*day; +37 data []*day 38 } <p> -40 func (p *dayArray) Len() int { return len(p.data); } -41 func (p *dayArray) Less(i, j int) bool { return p.data[i].num < p.data[j].num; } -42 func (p *dayArray) Swap(i, j int) { p.data[i], p.data[j] = p.data[j], p.data[i]; } +40 func (p *dayArray) Len() int { return len(p.data) } +41 func (p *dayArray) Less(i, j int) bool { return p.data[i].num < p.data[j].num } +42 func (p *dayArray) Swap(i, j int) { p.data[i], p.data[j] = p.data[j], p.data[i] } </pre> <p> <p> @@ -944,8 +955,8 @@ can just say <code>%d</code>; <code>Printf</code> knows the size and signedness integer and can do the right thing for you. The snippet <p> <pre> <!-- progs/print.go NR==10 NR==11 --> -10 var u64 uint64 = 1<<64-1; -11 fmt.Printf("%d %d\n", u64, int64(u64)); +10 var u64 uint64 = 1<<64-1 +11 fmt.Printf("%d %d\n", u64, int64(u64)) </pre> <p> prints @@ -957,11 +968,14 @@ prints In fact, if you're lazy the format <code>%v</code> will print, in a simple appropriate style, any value, even an array or structure. The output of <p> -<pre> <!-- progs/print.go NR==14 NR==17 --> -14 type T struct { a int; b string }; -15 t := T{77, "Sunset Strip"}; -16 a := []int{1, 2, 3, 4}; -17 fmt.Printf("%v %v %v\n", u64, t, a); +<pre> <!-- progs/print.go NR==14 NR==20 --> +14 type T struct { +15 a int +16 b string +17 } +18 t := T{77, "Sunset Strip"} +19 a := []int{1, 2, 3, 4} +20 fmt.Printf("%v %v %v\n", u64, t, a) </pre> <p> is @@ -977,9 +991,9 @@ of <code>%v</code> while <code>Println</code> inserts spaces between arguments and adds a newline. The output of each of these two lines is identical to that of the <code>Printf</code> call above. <p> -<pre> <!-- progs/print.go NR==18 NR==19 --> -18 fmt.Print(u64, " ", t, " ", a, "\n"); -19 fmt.Println(u64, t, a); +<pre> <!-- progs/print.go NR==21 NR==22 --> +21 fmt.Print(u64, " ", t, " ", a, "\n") +22 fmt.Println(u64, t, a) </pre> <p> If you have your own type you'd like <code>Printf</code> or <code>Print</code> to format, @@ -989,16 +1003,19 @@ the method and if so, use it rather than some other formatting. Here's a simple example. <p> <pre> <!-- progs/print_string.go NR==9 END --> -09 type testType struct { a int; b string } +09 type testType struct { +10 a int +11 b string +12 } <p> -11 func (t *testType) String() string { -12 return fmt.Sprint(t.a) + " " + t.b -13 } +14 func (t *testType) String() string { +15 return fmt.Sprint(t.a) + " " + t.b +16 } <p> -15 func main() { -16 t := &testType{77, "Sunset Strip"}; -17 fmt.Println(t) -18 } +18 func main() { +19 t := &testType{77, "Sunset Strip"} +20 fmt.Println(t) +21 } </pre> <p> Since <code>*testType</code> has a <code>String()</code> method, the @@ -1128,7 +1145,7 @@ operator <code><-</code> (receive) retrieves the next value on the channel. 17 // removing those divisible by 'prime'. 18 func filter(in, out chan int, prime int) { 19 for { -20 i := <-in; // Receive value of new variable 'i' from 'in'. +20 i := <-in // Receive value of new variable 'i' from 'in'. 21 if i % prime != 0 { 22 out <- i // Send 'i' to channel 'out'. 23 } @@ -1163,13 +1180,13 @@ together: <p> <pre> <!-- progs/sieve.go /func.main/ /^}/ --> 28 func main() { -29 ch := make(chan int); // Create a new channel. -30 go generate(ch); // Start generate() as a goroutine. +29 ch := make(chan int) // Create a new channel. +30 go generate(ch) // Start generate() as a goroutine. 31 for { -32 prime := <-ch; -33 fmt.Println(prime); -34 ch1 := make(chan int); -35 go filter(ch, ch1, prime); +32 prime := <-ch +33 fmt.Println(prime) +34 ch1 := make(chan int) +35 go filter(ch, ch1, prime) 36 ch = ch1 37 } 38 } @@ -1186,13 +1203,13 @@ of <code>generate</code>, from <code>progs/sieve1.go</code>: <p> <pre> <!-- progs/sieve1.go /func.generate/ /^}/ --> 10 func generate() chan int { -11 ch := make(chan int); +11 ch := make(chan int) 12 go func(){ 13 for i := 2; ; i++ { 14 ch <- i 15 } -16 }(); -17 return ch; +16 }() +17 return ch 18 } </pre> <p> @@ -1210,15 +1227,15 @@ The same change can be made to <code>filter</code>: <p> <pre> <!-- progs/sieve1.go /func.filter/ /^}/ --> 21 func filter(in chan int, prime int) chan int { -22 out := make(chan int); +22 out := make(chan int) 23 go func() { 24 for { 25 if i := <-in; i % prime != 0 { 26 out <- i 27 } 28 } -29 }(); -30 return out; +29 }() +30 return out 31 } </pre> <p> @@ -1227,16 +1244,16 @@ result, and while we're at it let's turn it into a factory too: <p> <pre> <!-- progs/sieve1.go /func.sieve/ /^}/ --> 33 func sieve() chan int { -34 out := make(chan int); +34 out := make(chan int) 35 go func() { -36 ch := generate(); +36 ch := generate() 37 for { -38 prime := <-ch; -39 out <- prime; -40 ch = filter(ch, prime); +38 prime := <-ch +39 out <- prime +40 ch = filter(ch, prime) 41 } -42 }(); -43 return out; +42 }() +43 return out 44 } </pre> <p> @@ -1244,9 +1261,9 @@ Now <code>main</code>'s interface to the prime sieve is a channel of primes: <p> <pre> <!-- progs/sieve1.go /func.main/ /^}/ --> 46 func main() { -47 primes := sieve(); +47 primes := sieve() 48 for { -49 fmt.Println(<-primes); +49 fmt.Println(<-primes) 50 } 51 } </pre> @@ -1262,8 +1279,8 @@ that will be used for the reply. <p> <pre> <!-- progs/server.go /type.request/ /^}/ --> 09 type request struct { -10 a, b int; -11 replyc chan int; +10 a, b int +11 replyc chan int 12 } </pre> <p> @@ -1274,8 +1291,8 @@ code that invokes the operation and responds to the request: 14 type binOp func(a, b int) int <p> 16 func run(op binOp, req *request) { -17 reply := op(req.a, req.b); -18 req.replyc <- reply; +17 reply := op(req.a, req.b) +18 req.replyc <- reply 19 } </pre> <p> @@ -1288,8 +1305,8 @@ a long-running operation, starting a goroutine to do the actual work. <pre> <!-- progs/server.go /func.server/ /^}/ --> 21 func server(op binOp, service chan *request) { 22 for { -23 req := <-service; -24 go run(op, req); // don't wait for it +23 req := <-service +24 go run(op, req) // don't wait for it 25 } 26 } </pre> @@ -1299,9 +1316,9 @@ connected to it: <p> <pre> <!-- progs/server.go /func.startServer/ /^}/ --> 28 func startServer(op binOp) chan *request { -29 req := make(chan *request); -30 go server(op, req); -31 return req; +29 req := make(chan *request) +30 go server(op, req) +31 return req 32 } </pre> <p> @@ -1311,22 +1328,22 @@ does it check the results. <p> <pre> <!-- progs/server.go /func.main/ /^}/ --> 34 func main() { -35 adder := startServer(func(a, b int) int { return a + b }); -36 const N = 100; -37 var reqs [N]request; +35 adder := startServer(func(a, b int) int { return a + b }) +36 const N = 100 +37 var reqs [N]request 38 for i := 0; i < N; i++ { -39 req := &reqs[i]; -40 req.a = i; -41 req.b = i + N; -42 req.replyc = make(chan int); -43 adder <- req; +39 req := &reqs[i] +40 req.a = i +41 req.b = i + N +42 req.replyc = make(chan int) +43 adder <- req 44 } 45 for i := N-1; i >= 0; i-- { // doesn't matter what order 46 if <-reqs[i].replyc != N + 2*i { -47 fmt.Println("fail at", i); +47 fmt.Println("fail at", i) 48 } 49 } -50 fmt.Println("done"); +50 fmt.Println("done") 51 } </pre> <p> @@ -1336,10 +1353,10 @@ we can provide a second, <code>quit</code> channel to the server: <p> <pre> <!-- progs/server1.go /func.startServer/ /^}/ --> 32 func startServer(op binOp) (service chan *request, quit chan bool) { -33 service = make(chan *request); -34 quit = make(chan bool); -35 go server(op, service, quit); -36 return service, quit; +33 service = make(chan *request) +34 quit = make(chan bool) +35 go server(op, service, quit) +36 return service, quit 37 } </pre> <p> @@ -1350,9 +1367,9 @@ It passes the quit channel to the <code>server</code> function, which uses it li 22 for { 23 select { 24 case req := <-service: -25 go run(op, req); // don't wait for it +25 go run(op, req) // don't wait for it 26 case <-quit: -27 return; +27 return 28 } 29 } 30 } @@ -1369,11 +1386,11 @@ All that's left is to strobe the <code>quit</code> channel at the end of main: <p> <pre> <!-- progs/server1.go /adder,.quit/ --> -40 adder, quit := startServer(func(a, b int) int { return a + b }); +40 adder, quit := startServer(func(a, b int) int { return a + b }) </pre> ... <pre> <!-- progs/server1.go /quit....true/ --> -55 quit <- true; +55 quit <- true </pre> <p> There's a lot more to Go programming and concurrent programming in general but this |