mirror of
https://github.com/duke-git/lancet.git
synced 2026-02-04 21:02:27 +08:00
365 lines
6.3 KiB
Markdown
365 lines
6.3 KiB
Markdown
# Function
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Package function can control the flow of function execution and support part of functional programming.
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<div STYLE="page-break-after: always;"></div>
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## Source:
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[https://github.com/duke-git/lancet/blob/main/function/function.go](https://github.com/duke-git/lancet/blob/main/function/function.go)
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[https://github.com/duke-git/lancet/blob/main/function/watcher.go](https://github.com/duke-git/lancet/blob/main/function/watcher.go)
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<div STYLE="page-break-after: always;"></div>
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## Usage:
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```go
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import (
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"github.com/duke-git/lancet/function"
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)
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```
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<div STYLE="page-break-after: always;"></div>
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## Index
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- [After](#After)
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- [Before](#Before)
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- [Curry](#Curry)
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- [Compose](#Compose)
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- [Debounced](#Debounced)
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- [Delay](#Delay)
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- [Watcher](#Watcher)
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<div STYLE="page-break-after: always;"></div>
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## Documentation
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### <span id="After">After</span>
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<p>Creates a function that invokes given func once it's called n or more times.</p>
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<b>Signature:</b>
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```go
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func After(n int, fn interface{}) func(args ...interface{}) []reflect.Value
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```
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<b>Example:</b>
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```go
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package main
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import (
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"fmt"
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"github.com/duke-git/lancet/function"
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)
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func main() {
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arr := []string{"a", "b"}
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f := function.After(len(arr), func(i int) int {
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fmt.Println("last print")
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return i
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})
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type cb func(args ...interface{}) []reflect.Value
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print := func(i int, s string, fn cb) {
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fmt.Printf("arr[%d] is %s \n", i, s)
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fn(i)
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}
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fmt.Println("arr is", arr)
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for i := 0; i < len(arr); i++ {
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print(i, arr[i], f)
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}
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//output:
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// arr is [a b]
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// arr[0] is a
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// arr[1] is b
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// last print
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}
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```
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### <span id="Before">Before</span>
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<p>creates a function that invokes func once it's called less than n times.</p>
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<b>Signature:</b>
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```go
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func Before(n int, fn interface{}) func(args ...interface{}) []reflect.Value
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```
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<b>Example:</b>
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```go
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package main
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import (
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"fmt"
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"github.com/duke-git/lancet/function"
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"github.com/duke-git/lancet/internal"
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)
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func main() {
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assert := internal.NewAssert(t, "TestBefore")
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arr := []string{"a", "b", "c", "d", "e"}
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f := function.Before(3, func(i int) int {
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return i
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})
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var res []int64
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type cb func(args ...interface{}) []reflect.Value
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appendStr := func(i int, s string, fn cb) {
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v := fn(i)
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res = append(res, v[0].Int())
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}
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for i := 0; i < len(arr); i++ {
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appendStr(i, arr[i], f)
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}
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expected := []int64{0, 1, 2, 2, 2}
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assert.Equal(expected, res)
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}
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```
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### <span id="Curry">Curry</span>
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<p>Make a curry function.</p>
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<b>Signature:</b>
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```go
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type Fn func(...interface{}) interface{}
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func (f Fn) Curry(i interface{}) func(...interface{}) interface{}
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```
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<b>Example:</b>
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```go
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package main
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import (
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"fmt"
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"github.com/duke-git/lancet/function"
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)
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func main() {
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add := func(a, b int) int {
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return a + b
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}
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var addCurry function.Fn = func(values ...interface{}) interface{} {
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return add(values[0].(int), values[1].(int))
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}
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add1 := addCurry.Curry(1)
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result := add1(2)
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fmt.Println(result) //3
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}
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```
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### <span id="Compose">Compose</span>
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<p>Compose the function list from right to left, then return the composed function.</p>
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<b>Signature:</b>
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```go
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func Compose(fnList ...func(...interface{}) interface{}) func(...interface{}) interface{}
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```
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<b>Example:</b>
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```go
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package main
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import (
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"fmt"
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"github.com/duke-git/lancet/function"
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)
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func main() {
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add1 := func(v ...interface{}) interface{} {
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return v[0].(int) + 1
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}
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add2 := func(v ...interface{}) interface{} {
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return v[0].(int) + 2
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}
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add3 := function.Compose(add1, add2)
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result := add3(1)
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fmt.Println(result) //4
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}
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```
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### <span id="Debounced">Debounced</span>
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<p>Creates a debounced function that delays invoking fn until after wait duration have elapsed since the last time the debounced function was invoked.</p>
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<b>Signature:</b>
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```go
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func Debounced(fn func(), duration time.Duration) func()
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```
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<b>Example:</b>
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```go
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package main
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import (
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"fmt"
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"github.com/duke-git/lancet/function"
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)
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func main() {
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count := 0
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add := func() {
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count++
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}
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debouncedAdd := function.Debounced(add, 50*time.Microsecond)
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function.debouncedAdd()
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function.debouncedAdd()
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function.debouncedAdd()
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function.debouncedAdd()
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time.Sleep(100 * time.Millisecond)
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fmt.Println(count) //1
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function.debouncedAdd()
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time.Sleep(100 * time.Millisecond)
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fmt.Println(count) //2
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}
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```
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### <span id="Delay">Delay</span>
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<p>Invoke function after delayed time.</p>
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<b>Signature:</b>
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```go
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func Delay(delay time.Duration, fn interface{}, args ...interface{})
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```
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<b>Example:</b>
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```go
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package main
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import (
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"fmt"
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"github.com/duke-git/lancet/function"
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)
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func main() {
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var print = func(s string) {
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fmt.Println(count) //test delay
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}
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function.Delay(2*time.Second, print, "test delay")
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}
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```
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### <span id="Schedule">Schedule</span>
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<p>Invoke function every duration time, until close the returned bool chan.</p>
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<b>Signature:</b>
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```go
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func Schedule(d time.Duration, fn interface{}, args ...interface{}) chan bool
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```
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<b>Example:</b>
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```go
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package main
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import (
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"fmt"
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"github.com/duke-git/lancet/function"
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)
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func main() {
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var res []string
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appendStr := func(s string) {
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res = append(res, s)
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}
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stop := function.Schedule(1*time.Second, appendStr, "*")
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time.Sleep(5 * time.Second)
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close(stop)
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fmt.Println(res) //[* * * * *]
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}
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```
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### <span id="Watcher">Watcher</span>
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<p>Watcher is used for record code excution time. can start/stop/reset the watch timer. get the elapsed time of function execution.</p>
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<b>Signature:</b>
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```go
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type Watcher struct {
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startTime int64
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stopTime int64
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excuting bool
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}
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func (w *Watcher) Start() //start the watcher
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func (w *Watcher) Stop() //stop the watcher
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func (w *Watcher) Reset() //reset the watcher
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func (w *Watcher) GetElapsedTime() time.Duration //get the elapsed time of function execution
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```
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<b>Example:</b>
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```go
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package main
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import (
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"fmt"
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"github.com/duke-git/lancet/function"
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)
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func main() {
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w := &function.Watcher{}
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w.Start()
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longRunningTask()
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fmt.Println(w.excuting) //true
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w.Stop()
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eapsedTime := w.GetElapsedTime().Milliseconds()
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fmt.Println(eapsedTime)
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w.Reset()
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fmt.Println(w.excuting) //false
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fmt.Println(w.startTime) //0
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fmt.Println(w.stopTime) //0
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}
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func longRunningTask() {
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var slice []int64
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for i := 0; i < 10000000; i++ {
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slice = append(slice, int64(i))
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}
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}
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```
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