歧视联盟和让绑定?
问题描述:
为什么在受歧视的工会中不允许绑定?我认为它必须与让绑定在默认构造函数中执行?歧视联盟和让绑定?
在次要记录中,有关如何重写AI_Choose
的建议将不胜感激。我想用AI保持加权优先级。我的想法是让AI_Weighted_Priority
继承AI_Priority
并覆盖选择。我不想处理荏苒不同长度的列表(不好的做法IMO)
open AI
type Condition =
| Closest of float
| Min
| Max
| Average
member this.Select (aiListWeight : list<AI * float>) =
match this with
| Closest(x) ->
aiListWeight
|> List.minBy (fun (ai, priority) -> abs(x - priority))
| Min -> aiListWeight |> List.minBy snd
| Max -> aiListWeight |> List.maxBy snd
| Average ->
let average = aiListWeight |> List.averageBy snd
aiListWeight
|> List.minBy (fun (ai, priority) -> abs(average - priority))
type AI_Choose =
| AI_Priority of list<AI> * Condition
| AI_Weighted_Priority of list<AI * float> * Condition
// I'm sad that I can't do this
let mutable chosen = Option<AI>.None
member this.Choose() =
match this with
| AI_Priority(aiList, condition) ->
aiList
|> List.map (fun ai -> ai, ai.Priority())
|> condition.Select
|> fst
| AI_Weighted_Priority(aiList, condition) ->
aiList
|> List.map (fun (ai, weight) -> ai, weight * ai.Priority())
|> condition.Select
|> fst
member this.Chosen
with get() =
if Option.isNone chosen then
chosen <- Some(this.Choose())
chosen.Value
and set(x) =
if Option.isSome chosen then
chosen.Value.Stop()
chosen <- Some(x)
x.Start()
interface AI with
member this.Start() =
this.Chosen.Start()
member this.Stop() =
this.Chosen.Stop()
member this.Reset() =
this.Chosen <- this.Choose()
member this.Priority() =
this.Chosen.Priority()
member this.Update(gameTime) =
this.Chosen.Update(gameTime)
答
允许在被区分的联合中“let”绑定是有意义的。我认为不可能的原因是受歧视的工会仍然基于OCaml设计,而对象来自.NET世界。 F#正试图尽可能地整合这两者,但它可能会更进一步。
无论如何,在我看来,你使用歧视联盟只是为了实现AI_Choose
类型的一些内部行为。在这种情况下,您可以分别声明一个区分的联合,并使用它来实现对象类型。
我相信你可以写这样的事情:
type AiChooseOptions =
| AI_Priority of list<AI> * Condition
| AI_Weighted_Priority of list<AI * float> * Condition
type AiChoose(aiOptions) =
let mutable chosen = Option<AI>.None
member this.Choose() =
match aiOptions with
| AI_Priority(aiList, condition) -> (...)
| AI_Weighted_Priority(aiList, condition) -> (...)
member this.Chosen (...)
interface AI with (...)
类层次结构和可识别联合之间的主要区别是,当涉及到可扩展性。类使得添加新类型变得更加容易,而区分的联合可以更容易地添加与类型配合使用的新函数(在您的情况中,AiChooseOptions),所以这可能是设计应用程序时首先要考虑的事情。
答
任何有兴趣我结束了从抽象基类派生AI_Priority
和AI_Weighted_Priority
。
[<AbstractClass>]
type AI_Choose() =
let mutable chosen = Option<AI>.None
abstract member Choose : unit -> AI
member this.Chosen
with get() =
if Option.isNone chosen then
chosen <- Some(this.Choose())
chosen.Value
and set(x) =
if Option.isSome chosen then
chosen.Value.Stop()
chosen <- Some(x)
x.Start()
interface AI with
member this.Start() =
this.Chosen.Start()
member this.Stop() =
this.Chosen.Stop()
member this.Reset() =
this.Chosen <- this.Choose()
member this.Priority() =
this.Chosen.Priority()
member this.Update(gameTime) =
this.Chosen.Update(gameTime)
type AI_Priority(aiList : list<AI>, condition : Condition) =
inherit AI_Choose()
override this.Choose() =
aiList
|> List.map (fun ai -> ai, ai.Priority())
|> condition.Select
|> fst
type AI_Weighted_Priority(aiList : list<AI * float>, condition : Condition) =
inherit AI_Choose()
override this.Choose() =
aiList
|> List.map (fun (ai, weight) -> ai, weight * ai.Priority())
|> condition.Select
|> fst
答
重温这段代码我最终采取了Tomas的建议,结果证明它更加清洁。
type AiChooseOptions =
| Priority of List<AI * Priority>
| WeightedPriority of List<AI * Priority * float>
member this.Choose(condition : Condition) =
match this with
| Priority(list) ->
list
|> List.map (fun (ai, priority) -> ai, priority.Priority())
|> condition.Select
| WeightedPriority(list) ->
list
|> List.map (fun (ai, p, weight) -> ai, p.Priority() * weight)
|> condition.Select
type AiChoose(condition, list : AiChooseOptions) =
let mutable chosen = Unchecked.defaultof<AI>, 0.0
interface AI with
member this.Update(gameTime) =
(fst chosen).Update(gameTime)
interface Priority with
member this.Priority() =
chosen <- list.Choose(condition)
(snd chosen)