作者：ShadowYD

關鍵字參數

眾所周知很多語言的function 中都支持 key=word 關鍵字參數, 但 golang 是不支持的, 我們可以利用泛型去簡單的實現.

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func?DefaultKeyWordParams[D?any](defVal?D,?params?...D)?D?{
??????if?len(params)?==?0?{
??????????????return?defVal
??????}
??????return?params[0]
}


func?test(category?...string)?{
??//?不填寫則返回默認值
??realCategory?:=?DefaultKeyWordParams[string]("AGroup",?category...)
??fmt.Println(realCategory)
}

func?main?()?{
???test()
}

?

快速排序

UpdateAt: 2023-02-22

實現一個可進行控制反轉的通用類型快速排序, 解決一下原生的sort包進行類型定義的繁瑣.

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//?QuickSort?通用快速排序
func?QuickSort[T?any](arr?[]T,?compareFn?func(a,?b?T)?bool)?{
??????if?len(arr)?

	?

	測試用例

	?
func?TestQuickSort(t?*testing.T)?{
??????nums?:=?[]int{9,?3,?1,?7,?4,?8,?6,?2,?5}
??????fmt.Println("Unsorted:",?nums)

??????QuickSort[int](nums,?func(a,?b?int)?bool?{
??????????????return?a?

	?

	去重復

	這是一個簡單的實現, 復雜點可以通過回調 + 泛型來實現;

	?
func?RemoveDuplicate[T?string?|?int?|?float64](duplicateSlice?[]T)?[]T?{
??????set?:=?map[T]interface{}{}
??????res?:=?[]T{}
??????for?_,?item?:=?range?duplicateSlice?{
??????????????_,?ok?:=?set[item]
??????????????if?!ok?{
??????????????????????res?=?append(res,?item)
??????????????????????set[item]?=?nil
??????????????}
??????}
??????return?res
}

func?main()?{
??????fmt.Println(RemoveDuplicate[string]([]string{"a",?"c",?"a"}))
??????fmt.Println(RemoveDuplicate[int]([]int{1,?2,?1,?1,?1}))
}



	?

	通過控制反轉實現通用的去重復方法, 支持任意類型;

	?
type?Student?struct?{
??????Name?string
??????Age??int
}

func?NewStudent(name?string,?age?int)?*Student?{
??????return?&Student{Name:?name,?Age:?age}
}

func?DefaultFilter(item?interface{})?(uniqueKey?interface{})?{
??????return?item.(*Student).Name
}

func?RemoveDuplicateWithFilter[T?comparable](compareSlice?[]T,?filterFunc?func(item?interface{})?(key?interface{}))?[]T?{
??????set?:=?map[interface{}]interface{}{}
??????res?:=?[]T{}
??????for?_,?item?:=?range?compareSlice?{
??????????????i?:=?filterFunc(item)
??????????????_,?ok?:=?set[i]
??????????????if?!ok?{
??????????????????????res?=?append(res,?item)
??????????????????????set[i]?=?nil
??????????????}
??????}
??????return?res
}

func?main()?{
??????s?:=?[]*Student{
??????????????NewStudent("a",?1),
??????????????NewStudent("a",?1),
??????????????NewStudent("b",?2),
??????????????NewStudent("b",?2),
??????}
??????l?:=?RemoveDuplicateWithFilter[*Student](s,?DefaultFilter)
??????for?_,?i?:=?range?l?{
??????????????fmt.Println(i.Name,?i.Age)
??????}
}



	?

	聯合約束類型

	該例子只是一個演示, 沒有實際效果
type?ID?interface?{
??int?|?string
}

//?寫法??[T?ID,?D?string]?==?[T?int?|?string,?D?string]
type?UserModel[T?ID,?D?string]?struct?{
??????Id???T
??????Name?D
}

func?NewUserModel[A?ID,?D?string](id?A,?name?D)?*UserModel[A,?D]?{
??????return?&UserModel[A,?D]{Id:?id,?Name:?name}
}

func?main()?{
??????fmt.Println(NewUserModel[int,?string](10,?"hello"))
??????fmt.Println(NewUserModel[string,?string]("10",?"hello"))
}



	?

	分頁

	這是一段線上在使用的分頁代碼, 當無法使用外部存儲器進行分頁時直接使用該對象進行分頁, 支持任意類型;
type?KeepItem?bool

//?若需要保留的item?則返回true?即可
type?FilterFunc?func(item?interface{})?KeepItem

type?PageList[T?any]?struct?{
??????Total?int?`json:"total"`
??????Page??int?`json:"page"`
??????Size??int?`json:"size"`
??????List??[]T?`json:"list"`
}

type?Pager[T?any]?struct?{
??????limit???int
??????offset??int
??????total???int
??????pageCnt?int
??????list????[]T
}

func?NewPager[T?any](list?[]T)?*Pager[T]?{
??????return?&Pager[T]{
??????????????limit:??10,
??????????????offset:?1,
??????????????total:??len(list),
??????????????list:???list,
??????}
}

func?(this?*Pager[T])?Filter(filterFn?FilterFunc)?*Pager[T]?{
??????tmpList?:=?[]T{}
??????for?_,?item?:=?range?this.list?{
??????????????if?filterFn(&item)?{
??????????????????????tmpList?=?append(tmpList,?item)
??????????????}
??????}
??????this.list?=?tmpList
??????this.total?=?len(tmpList)
??????return?this
}

func?(this?*Pager[T])?Offset(c?int)?*Pager[T]?{
??????this.offset?=?c
??????return?this
}

func?(this?*Pager[T])?Limit(c?int)?*Pager[T]?{
??????this.limit?=?c
??????return?this
}

func?(this?*Pager[T])?List()?[]T?{
??????//?頁碼
??????if?this.offset?<=?0?{
??????????????this.offset?=?1
??????}
??????//?size
??????if?this.limit?>?this.total?{
??????????????this.limit?=?this.total
??????}
??????//?總頁數
??????this.pageCnt?=?int(math.Ceil(float64(this.total)?/?float64(this.limit)))
??????if?this.offset?>?this.pageCnt?{
??????????????return?[]T{}
??????}
??????startIdx?:=?(this.offset?-?1)?*?this.limit
??????endIdx?:=?startIdx?+?this.limit

??????if?endIdx?>?this.total?{
??????????????endIdx?=?this.total
??????}

??????return?this.list[startIdx:endIdx]
}

func?(this?*Pager[T])?Output()?*PageList[T]?{

??????return?&PageList[T]{
??????????????Total:?this.total,
??????????????Page:??this.offset,
??????????????Size:??this.limit,
??????????????List:??this.list,
??????}
}

//?test
func?main?()?{
??page?:=?NewPager[int]([]int{1,?2,?3,?4,?5,?6,?7,?8,?9,?10})
??????list?:=?page.Offset(1).Limit(3).Filter(func(item?interface{})?KeepItem?{
??if?*item.(*int)%2?==?1?{
???return?true
??}
??return?false
??????}).List()
??????fmt.Println(list)
}




	?

	通用初始化模型

	可以解決在多態下使用同一個初始化函數進行對象初始化, 寫法上有點繞大家自行多實驗幾次就能明白.
type?ModelObj?interface?{
??????User?|?Product
}

type?User?struct?{
??????Uid?int
}

func?(this?*User)?SetId(id?int)?{
??????this.Uid?=?id
}

type?Product?struct?{
??????Pid?int
}

func?(this?*Product)?SetId(id?int)?{
??????this.Pid?=?id
}

//?TrimModelObj?是一個動態類型的?Interface,?由M決定當前Interface的最終類型
type?TrimModelObj[M?ModelObj]?interface?{
??????*M
??????SetId(id?int)
}

//?TrimModelObj[Model]?由第二個參數決定當前的動態類型；
//?NewModelObj[*User,?User](32)?如?Model?是?User?類型,?最終?TrimModelObj?==?*User，所以我們需要為?Trim?傳遞?*User
func?NewModelObj[Trim?TrimModelObj[Model],?Model?ModelObj](id?int)?Trim?{
??????m?:=?new(Model)
??????t?:=?Trim(m)
??????fmt.Printf("%p?
",?m)
??????//?類型轉換成指定的*Model
??????t.SetId(id)
??????return?t
}


func?main()?{
??????//?new?user?model?object
??????user?:=?NewModelObj[*User,?User](32)
??????fmt.Printf("%p?
",?user)
??????fmt.Printf("%T?
",?user)
??????fmt.Println(user.Uid)

??????//?new?product?model?object
??????prod?:=?NewModelObj[*Product,?Product](18)
??????fmt.Printf("%p?
",?prod)
??????fmt.Printf("%T?
",?prod)
??????fmt.Println(prod.Pid)
}


	?

	　　審核編輯：湯梓紅

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