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Mini IoC Container
Minimal Inversion of Control (IoC) Container for Dependency Injection (DI) in under 100 lines of code. Implements the 3 Rs of DI: Register, Resolve, Release.
Note: missing thread safety and fluent interface.
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open System
open System.Collections.Generic
type Lifetime = Singleton | Transient
type private Constructor =
| Reflected of Type
| Factory of (unit -> obj)
type Container () =
let catalog = Dictionary<Type, Constructor * Lifetime>()
let singletons = Dictionary<Type,obj>()
let rec resolve t =
match catalog.TryGetValue(t) with
| true, (Factory f, lifetime)->
obtain t (fun () -> f() |> Some) lifetime
| true, (Reflected u, lifetime) ->
obtain t (fun () -> construct u) lifetime
| false, _ ->
obtain t (fun () -> construct t) Singleton
and obtain t f lifetime =
match singletons.TryGetValue t with
| true, value -> Some value
| false, _ ->
let result = f()
result |> Option.iter (fun value -> store lifetime t value)
result
and store lifetime t value =
match lifetime with
| Singleton -> singletons.Add(t,value)
| Transient -> ()
and construct t =
t.GetConstructors() |> Array.tryPick (fun ctr ->
let ps = ctr.GetParameters()
let args = ps |> Array.map (fun p -> resolve p.ParameterType)
match args |> Array.forall Option.isSome with
| true -> args |> (Array.choose id) |> ctr.Invoke |> Some
| false -> None
)
member container.Register<'TAbstract when 'TAbstract : not struct>
(concreteType:Type, lifetime:Lifetime) =
catalog.Add(typeof<'TAbstract>, (Reflected(concreteType),lifetime))
member container.Register<'TAbstract when 'TAbstract : not struct>
(concreteType:Type) =
container.Register<'TAbstract>(concreteType,Singleton)
member container.Register<'TAbstract when 'TAbstract : not struct>
(f:unit->'TAbstract, lifetime:Lifetime) =
catalog.Add(typeof<'TAbstract>, (Factory(f >> box), lifetime))
member container.Register(f:unit->'TAbstract) =
container.Register(f, Singleton)
member container.Resolve<'TAbstract when 'TAbstract : not struct>() =
let t = typeof<'TAbstract>
match resolve t with
| Some value -> value :?> 'TAbstract
| None -> sprintf "Failed to resolve %A" t |> invalidOp
member container.Release(instance:obj) =
singletons
|> Seq.filter (fun pair -> pair.Value = instance)
|> Seq.toList
|> List.iter (fun pair -> singletons.Remove(pair.Key) |> ignore)
module Usage =
let container = new Container()
type A () =
do printfn "A"
type B () =
do printfn "B"
type C (a:A, b:B) =
do printfn "C"
container.Register((fun () -> printfn "B lambda"; B()), Transient)
container.Register<C>(typeof<C>)
let c = container.Resolve<C>()
let c' = container.Resolve<C>()
container.Release(c)
let c'' = container.Resolve<C>()
type ICalculate =
abstract member Incr : int -> int
type Calculator () =
interface ICalculate with
member this.Incr(x:int) = x + 1
container.Register<ICalculate>(typeof<Calculator>)
let calc = container.Resolve<ICalculate>()
printfn "%d" (calc.Incr 1)
Console.ReadLine() |> ignore
|
namespace System
namespace System.Collections
namespace System.Collections.Generic
type Lifetime =
| Singleton
| Transient
Full name: Script.Lifetime
union case Lifetime.Singleton: Lifetime
union case Lifetime.Transient: Lifetime
type private Constructor =
| Reflected of Type
| Factory of (unit -> obj)
Full name: Script.Constructor
union case Constructor.Reflected: Type -> Constructor
type Type =
inherit MemberInfo
member Assembly : Assembly
member AssemblyQualifiedName : string
member Attributes : TypeAttributes
member BaseType : Type
member ContainsGenericParameters : bool
member DeclaringMethod : MethodBase
member DeclaringType : Type
member Equals : o:obj -> bool + 1 overload
member FindInterfaces : filter:TypeFilter * filterCriteria:obj -> Type[]
member FindMembers : memberType:MemberTypes * bindingAttr:BindingFlags * filter:MemberFilter * filterCriteria:obj -> MemberInfo[]
...
Full name: System.Type
union case Constructor.Factory: (unit -> obj) -> Constructor
type unit = Unit
Full name: Microsoft.FSharp.Core.unit
type obj = Object
Full name: Microsoft.FSharp.Core.obj
Multiple items
type Container =
new : unit -> Container
member Register : concreteType:Type -> unit
member Register : f:(unit -> 'TAbstract) -> unit (requires reference type)
member Register : concreteType:Type * lifetime:Lifetime -> unit
member Register : f:(unit -> 'TAbstract) * lifetime:Lifetime -> unit (requires reference type)
member Release : instance:obj -> unit
member Resolve : unit -> 'TAbstract (requires reference type)
Full name: Script.Container
--------------------
new : unit -> Container
val catalog : Dictionary<Type,(Constructor * Lifetime)>
Multiple items
type Dictionary<'TKey,'TValue> =
new : unit -> Dictionary<'TKey, 'TValue> + 5 overloads
member Add : key:'TKey * value:'TValue -> unit
member Clear : unit -> unit
member Comparer : IEqualityComparer<'TKey>
member ContainsKey : key:'TKey -> bool
member ContainsValue : value:'TValue -> bool
member Count : int
member GetEnumerator : unit -> Enumerator<'TKey, 'TValue>
member GetObjectData : info:SerializationInfo * context:StreamingContext -> unit
member Item : 'TKey -> 'TValue with get, set
...
nested type Enumerator
nested type KeyCollection
nested type ValueCollection
Full name: System.Collections.Generic.Dictionary<_,_>
--------------------
Dictionary() : unit
Dictionary(capacity: int) : unit
Dictionary(comparer: IEqualityComparer<'TKey>) : unit
Dictionary(dictionary: IDictionary<'TKey,'TValue>) : unit
Dictionary(capacity: int, comparer: IEqualityComparer<'TKey>) : unit
Dictionary(dictionary: IDictionary<'TKey,'TValue>, comparer: IEqualityComparer<'TKey>) : unit
val singletons : Dictionary<Type,obj>
val resolve : (Type -> obj option)
val t : Type
Dictionary.TryGetValue(key: Type, value: byref<Constructor * Lifetime>) : bool
val f : (unit -> obj)
val lifetime : Lifetime
val obtain : (Type -> (unit -> obj option) -> Lifetime -> obj option)
union case Option.Some: Value: 'T -> Option<'T>
val u : Type
val construct : (Type -> obj option)
val f : (unit -> obj option)
Dictionary.TryGetValue(key: Type, value: byref<obj>) : bool
val value : obj
val result : obj option
module Option
from Microsoft.FSharp.Core
val iter : action:('T -> unit) -> option:'T option -> unit
Full name: Microsoft.FSharp.Core.Option.iter
val store : (Lifetime -> Type -> obj -> unit)
Dictionary.Add(key: Type, value: obj) : unit
Type.GetConstructors() : Reflection.ConstructorInfo []
Type.GetConstructors(bindingAttr: Reflection.BindingFlags) : Reflection.ConstructorInfo []
type Array =
member Clone : unit -> obj
member CopyTo : array:Array * index:int -> unit + 1 overload
member GetEnumerator : unit -> IEnumerator
member GetLength : dimension:int -> int
member GetLongLength : dimension:int -> int64
member GetLowerBound : dimension:int -> int
member GetUpperBound : dimension:int -> int
member GetValue : [<ParamArray>] indices:int[] -> obj + 7 overloads
member Initialize : unit -> unit
member IsFixedSize : bool
...
Full name: System.Array
val tryPick : chooser:('T -> 'U option) -> array:'T [] -> 'U option
Full name: Microsoft.FSharp.Collections.Array.tryPick
val ctr : Reflection.ConstructorInfo
val ps : Reflection.ParameterInfo []
Reflection.MethodBase.GetParameters() : Reflection.ParameterInfo []
val args : obj option []
val map : mapping:('T -> 'U) -> array:'T [] -> 'U []
Full name: Microsoft.FSharp.Collections.Array.map
val p : Reflection.ParameterInfo
property Reflection.ParameterInfo.ParameterType: Type
val forall : predicate:('T -> bool) -> array:'T [] -> bool
Full name: Microsoft.FSharp.Collections.Array.forall
val isSome : option:'T option -> bool
Full name: Microsoft.FSharp.Core.Option.isSome
val choose : chooser:('T -> 'U option) -> array:'T [] -> 'U []
Full name: Microsoft.FSharp.Collections.Array.choose
val id : x:'T -> 'T
Full name: Microsoft.FSharp.Core.Operators.id
Reflection.ConstructorInfo.Invoke(parameters: obj []) : obj
Reflection.MethodBase.Invoke(obj: obj, parameters: obj []) : obj
Reflection.ConstructorInfo.Invoke(invokeAttr: Reflection.BindingFlags, binder: Reflection.Binder, parameters: obj [], culture: Globalization.CultureInfo) : obj
Reflection.MethodBase.Invoke(obj: obj, invokeAttr: Reflection.BindingFlags, binder: Reflection.Binder, parameters: obj [], culture: Globalization.CultureInfo) : obj
union case Option.None: Option<'T>
val container : Container
member Container.Register : concreteType:Type * lifetime:Lifetime -> unit
Full name: Script.Container.Register
val not : value:bool -> bool
Full name: Microsoft.FSharp.Core.Operators.not
val concreteType : Type
Dictionary.Add(key: Type, value: Constructor * Lifetime) : unit
val typeof<'T> : Type
Full name: Microsoft.FSharp.Core.Operators.typeof
member Container.Register : concreteType:Type -> unit
Full name: Script.Container.Register
member Container.Register : concreteType:Type -> unit
member Container.Register : f:(unit -> 'TAbstract) -> unit (requires reference type)
member Container.Register : concreteType:Type * lifetime:Lifetime -> unit
member Container.Register : f:(unit -> 'TAbstract) * lifetime:Lifetime -> unit (requires reference type)
member Container.Register : f:(unit -> 'TAbstract) * lifetime:Lifetime -> unit (requires reference type)
Full name: Script.Container.Register
val f : (unit -> 'TAbstract) (requires reference type)
val box : value:'T -> obj
Full name: Microsoft.FSharp.Core.Operators.box
member Container.Register : f:(unit -> 'TAbstract) -> unit (requires reference type)
Full name: Script.Container.Register
member Container.Resolve : unit -> 'TAbstract (requires reference type)
Full name: Script.Container.Resolve
val sprintf : format:Printf.StringFormat<'T> -> 'T
Full name: Microsoft.FSharp.Core.ExtraTopLevelOperators.sprintf
val invalidOp : message:string -> 'T
Full name: Microsoft.FSharp.Core.Operators.invalidOp
member Container.Release : instance:obj -> unit
Full name: Script.Container.Release
val instance : obj
module Seq
from Microsoft.FSharp.Collections
val filter : predicate:('T -> bool) -> source:seq<'T> -> seq<'T>
Full name: Microsoft.FSharp.Collections.Seq.filter
val pair : KeyValuePair<Type,obj>
property KeyValuePair.Value: obj
val toList : source:seq<'T> -> 'T list
Full name: Microsoft.FSharp.Collections.Seq.toList
Multiple items
type List<'T> =
new : unit -> List<'T> + 2 overloads
member Add : item:'T -> unit
member AddRange : collection:IEnumerable<'T> -> unit
member AsReadOnly : unit -> ReadOnlyCollection<'T>
member BinarySearch : item:'T -> int + 2 overloads
member Capacity : int with get, set
member Clear : unit -> unit
member Contains : item:'T -> bool
member ConvertAll<'TOutput> : converter:Converter<'T, 'TOutput> -> List<'TOutput>
member CopyTo : array:'T[] -> unit + 2 overloads
...
nested type Enumerator
Full name: System.Collections.Generic.List<_>
--------------------
List() : unit
List(capacity: int) : unit
List(collection: IEnumerable<'T>) : unit
val iter : action:('T -> unit) -> list:'T list -> unit
Full name: Microsoft.FSharp.Collections.List.iter
Dictionary.Remove(key: Type) : bool
property KeyValuePair.Key: Type
val ignore : value:'T -> unit
Full name: Microsoft.FSharp.Core.Operators.ignore
module Usage
from Script
val container : Container
Full name: Script.Usage.container
type A =
new : unit -> A
Full name: Script.Usage.A
val printfn : format:Printf.TextWriterFormat<'T> -> 'T
Full name: Microsoft.FSharp.Core.ExtraTopLevelOperators.printfn
type B =
new : unit -> B
Full name: Script.Usage.B
type C =
new : a:A * b:B -> C
Full name: Script.Usage.C
val a : A
val b : B
new : unit -> B
val c : C
Full name: Script.Usage.c
member Container.Resolve : unit -> 'TAbstract (requires reference type)
val c' : C
Full name: Script.Usage.c'
member Container.Release : instance:obj -> unit
val c'' : C
Full name: Script.Usage.c''
type ICalculate =
interface
abstract member Incr : int -> int
end
Full name: Script.Usage.ICalculate
abstract member ICalculate.Incr : int -> int
Full name: Script.Usage.ICalculate.Incr
Multiple items
val int : value:'T -> int (requires member op_Explicit)
Full name: Microsoft.FSharp.Core.Operators.int
--------------------
type int = int32
Full name: Microsoft.FSharp.Core.int
--------------------
type int<'Measure> = int
Full name: Microsoft.FSharp.Core.int<_>
Multiple items
type Calculator =
interface ICalculate
new : unit -> Calculator
Full name: Script.Usage.Calculator
--------------------
new : unit -> Calculator
val this : Calculator
override Calculator.Incr : x:int -> int
Full name: Script.Usage.Calculator.Incr
val x : int
val calc : ICalculate
Full name: Script.Usage.calc
abstract member ICalculate.Incr : int -> int
type Console =
static member BackgroundColor : ConsoleColor with get, set
static member Beep : unit -> unit + 1 overload
static member BufferHeight : int with get, set
static member BufferWidth : int with get, set
static member CapsLock : bool
static member Clear : unit -> unit
static member CursorLeft : int with get, set
static member CursorSize : int with get, set
static member CursorTop : int with get, set
static member CursorVisible : bool with get, set
...
Full name: System.Console
Console.ReadLine() : string
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