-
Notifications
You must be signed in to change notification settings - Fork 1
/
Defer.go
51 lines (44 loc) · 1.01 KB
/
Defer.go
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
// Defer
package main
/*
Defer is used to ensure that a function call
is performed later in a program has execution,
usually for purposes of cleanup.
defer is often used where e.g. ensure and
finally would be used in other languages.
*/
import (
"fmt"
"os"
)
func createFile(p string) *os.File {
fmt.Println("creating.")
f, err := os.Create(p)
if err != nil {
panic(err)
}
return f
}
func writeFile(f *os.File) {
fmt.Println("writing")
fmt.Fprintln(f, "data")
}
func closeFile(f *os.File) {
fmt.Println("closing")
f.Close()
}
func Defer_() {
/*
Suppose we wanted to create a file,
write to it, and then close when we are done.
Here is how we could do that with defer.
Immediately after getting a file object with createFile,
we defer the closing of that file with closeFile.
This will be executed at the end of
the enclosing function (main),
after writeFile has finished.
*/
f := createFile("defer.txt")
defer closeFile(f)
writeFile(f)
}