Action<T1,T2,T3,T4> 代理人
定義
重要
部分資訊涉及發行前產品,在發行之前可能會有大幅修改。 Microsoft 對此處提供的資訊,不做任何明確或隱含的瑕疵擔保。
封裝具有 4 個參數且沒有傳回值的方法。
generic <typename T1, typename T2, typename T3, typename T4>
public delegate void Action(T1 arg1, T2 arg2, T3 arg3, T4 arg4);
public delegate void Action<in T1,in T2,in T3,in T4>(T1 arg1, T2 arg2, T3 arg3, T4 arg4);
public delegate void Action<T1,T2,T3,T4>(T1 arg1, T2 arg2, T3 arg3, T4 arg4);
type Action<'T1, 'T2, 'T3, 'T4> = delegate of 'T1 * 'T2 * 'T3 * 'T4 -> unit
Public Delegate Sub Action(Of In T1, In T2, In T3, In T4)(arg1 As T1, arg2 As T2, arg3 As T3, arg4 As T4)
Public Delegate Sub Action(Of T1, T2, T3, T4)(arg1 As T1, arg2 As T2, arg3 As T3, arg4 As T4)
類型參數
參數
- arg1
- T1
由這個委派所封裝之方法的第一個參數。
- arg2
- T2
此委派封裝之方法的第二個參數。
- arg3
- T3
此委派封裝之方法的第三個參數。
- arg4
- T4
這個委派所封裝之方法的第四個參數。
備註
您可以使用 Action<T1,T2,T3,T4> 委派將方法當做參數傳遞,而不需明確宣告自訂委派。 封裝的方法必須對應至這個委派所定義的方法簽章。 這表示封裝的方法必須有四個參數,這些參數全都以傳值方式傳遞給它,而且不能傳回值。 (在 C# 中,方法必須傳回 void
。在 F# 中,方法或函式必須傳回單位。在 Visual Basic 中,它必須由 ... End Sub
建構定義 Sub
。它也可以是傳回忽略之值的方法。) 通常,這類方法會用來執行作業。
注意
若要參考具有四個參數並傳回值的方法,請改用泛型 Func<T1,T2,T3,T4,TResult> 委派。
當您使用委派時 Action<T1,T2,T3,T4> ,不需要明確定義封裝具有四個參數之方法的委派。 例如,下列程式碼會明確宣告名為 StringCopy
的委派,並將方法的 CopyStrings
參考指派給其委派實例。
using System;
delegate void StringCopy(string[] stringArray1,
string[] stringArray2,
int indexToStart,
int numberToCopy);
public class TestDelegate
{
public static void Main()
{
string[] ordinals = ["First", "Second", "Third", "Fourth", "Fifth",
"Sixth", "Seventh", "Eighth", "Ninth", "Tenth"];
string[] copiedOrdinals = new string[ordinals.Length];
StringCopy copyOperation = CopyStrings;
copyOperation(ordinals, copiedOrdinals, 3, 5);
Console.WriteLine();
foreach (string ordinal in copiedOrdinals)
Console.WriteLine(string.IsNullOrEmpty(ordinal) ? "<None>" : ordinal);
}
private static void CopyStrings(string[] source, string[] target,
int startPos, int number)
{
if (source.Length != target.Length)
throw new IndexOutOfRangeException("The source and target arrays must have the same number of elements.");
for (int ctr = startPos; ctr <= startPos + number - 1; ctr++)
target[ctr] = source[ctr];
}
}
open System
type StringCopy = delegate of stringArray1: string [] *
stringArray2: string [] *
indexToStart: int *
numberToCopy: int -> unit
let copyStrings (source: string []) (target: string []) startPos number =
if source.Length <> target.Length then
raise (IndexOutOfRangeException "The source and target arrays must have the same number of elements.")
for i = startPos to startPos + number - 1 do
target.[i] <- source.[i]
let ordinals =
[| "First"; "Second"; "Third"; "Fourth"; "Fifth"
"Sixth"; "Seventh"; "Eighth"; "Ninth"; "Tenth" |]
let copiedOrdinals: string [] = Array.zeroCreate ordinals.Length
let copyOperation = StringCopy copyStrings
copyOperation.Invoke(ordinals, copiedOrdinals, 3, 5)
for ordinal in copiedOrdinals do
printfn "%s" (if String.IsNullOrEmpty ordinal then "<None>" else ordinal)
Delegate Sub StringCopy(stringArray1() As String, _
stringArray2() As String, _
indexToStart As Integer, _
numberToCopy As Integer)
Module TestDelegate
Public Sub RunIt()
Dim ordinals() As String = {"First", "Second", "Third", "Fourth",
"Fifth", "Sixth", "Seventh", "Eighth",
"Ninth", "Tenth"}
Dim copiedOrdinals(ordinals.Length - 1) As String
Dim copyOperation As StringCopy = AddressOf CopyStrings
copyOperation(ordinals, copiedOrdinals, 3, 5)
Console.WriteLine()
For Each ordinal As String In copiedOrdinals
If String.IsNullOrEmpty(ordinal) Then
Console.WriteLine("<None>")
Else
Console.WriteLine(ordinal)
End If
Next
End Sub
Private Sub CopyStrings(source() As String, target() As String, _
startPos As Integer, number As Integer)
If source.Length <> target.Length Then
Throw New IndexOutOfRangeException("The source and target arrays" & _
" must have the same number of elements.")
End If
For ctr As Integer = startPos to startpos + number - 1
target(ctr) = source(ctr)
Next
End Sub
End Module
下列範例會具現化委派, Action<T1,T2,T3,T4> 而不是明確定義新的委派,並將具名方法指派給它,藉此簡化此程式碼。
using System;
public class TestAction4
{
public static void Main()
{
string[] ordinals = ["First", "Second", "Third", "Fourth", "Fifth",
"Sixth", "Seventh", "Eighth", "Ninth", "Tenth"];
string[] copiedOrdinals = new string[ordinals.Length];
Action<string[], string[], int, int> copyOperation = CopyStrings;
copyOperation(ordinals, copiedOrdinals, 3, 5);
Console.WriteLine();
foreach (string ordinal in copiedOrdinals)
Console.WriteLine(string.IsNullOrEmpty(ordinal) ? "<None>" : ordinal);
}
private static void CopyStrings(string[] source, string[] target,
int startPos, int number)
{
if (source.Length != target.Length)
throw new IndexOutOfRangeException("The source and target arrays must have the same number of elements.");
for (int ctr = startPos; ctr <= startPos + number - 1; ctr++)
target[ctr] = source[ctr];
}
}
open System
let copyStrings (source: string []) (target: string []) startPos number =
if source.Length <> target.Length then
raise (IndexOutOfRangeException "The source and target arrays must have the same number of elements.")
for i = startPos to startPos + number - 1 do
target.[i] <- source.[i]
let ordinals =
[| "First"; "Second"; "Third"; "Fourth"; "Fifth"
"Sixth"; "Seventh"; "Eighth"; "Ninth"; "Tenth" |]
let copiedOrdinals: string [] = Array.zeroCreate ordinals.Length
let copyOperation = Action<_, _, _, _> copyStrings
copyOperation.Invoke(ordinals, copiedOrdinals, 3, 5)
for ordinal in copiedOrdinals do
printfn "%s" (if String.IsNullOrEmpty ordinal then "<None>" else ordinal)
Module TestAction4
Public Sub RunIt()
Dim ordinals() As String = {"First", "Second", "Third", "Fourth",
"Fifth", "Sixth", "Seventh", "Eighth",
"Ninth", "Tenth"}
Dim copiedOrdinals(ordinals.Length - 1) As String
Dim copyOperation As Action(Of String(), String(), Integer, Integer) =
AddressOf CopyStrings
copyOperation(ordinals, copiedOrdinals, 3, 5)
Console.WriteLine()
For Each ordinal As String In copiedOrdinals
If String.IsNullOrEmpty(ordinal) Then
Console.WriteLine("<None>")
Else
Console.WriteLine(ordinal)
End If
Next
End Sub
Private Sub CopyStrings(source() As String, target() As String, _
startPos As Integer, number As Integer)
If source.Length <> target.Length Then
Throw New IndexOutOfRangeException("The source and target arrays" & _
" must have the same number of elements.")
End If
For ctr As Integer = startPos to startpos + number - 1
target(ctr) = source(ctr)
Next
End Sub
End Module
您也可以在 Action<T1,T2,T3,T4> C# 中搭配匿名方法使用委派,如下列範例所示。 (如需匿名方法的簡介,請參閱 Anonymous Methods.)
using System;
public class TestAnonymousMethod
{
public static void Main()
{
string[] ordinals = ["First", "Second", "Third", "Fourth", "Fifth",
"Sixth", "Seventh", "Eighth", "Ninth", "Tenth"];
string[] copiedOrdinals = new string[ordinals.Length];
Action<string[], string[], int, int> copyOperation =
delegate (string[] s1, string[] s2,
int pos, int num)
{ CopyStrings(s1, s2, pos, num); };
copyOperation(ordinals, copiedOrdinals, 3, 5);
Console.WriteLine();
foreach (string ordinal in copiedOrdinals)
Console.WriteLine(string.IsNullOrEmpty(ordinal) ? "<None>" : ordinal);
}
private static void CopyStrings(string[] source, string[] target,
int startPos, int number)
{
if (source.Length != target.Length)
throw new IndexOutOfRangeException("The source and target arrays must have the same number of elements.");
for (int ctr = startPos; ctr <= startPos + number - 1; ctr++)
target[ctr] = source[ctr];
}
}
您也可以將 Lambda 運算式指派給 Action<T1,T2,T3,T4> 委派實例,如下列範例所示。 (如需 Lambda 運算式的簡介,請參閱 Lambda 運算式 (C#) 或 Lambda 運算式 (F#) .)
using System;
public class TestLambdaExpression
{
public static void Main()
{
string[] ordinals = ["First", "Second", "Third", "Fourth", "Fifth",
"Sixth", "Seventh", "Eighth", "Ninth", "Tenth"];
string[] copiedOrdinals = new string[ordinals.Length];
Action<string[], string[], int, int> copyOperation = (s1, s2, pos, num)
=> CopyStrings(s1, s2, pos, num);
copyOperation(ordinals, copiedOrdinals, 3, 5);
Console.WriteLine();
foreach (string ordinal in copiedOrdinals)
Console.WriteLine(string.IsNullOrEmpty(ordinal) ? "<None>" : ordinal);
}
private static void CopyStrings(string[] source, string[] target,
int startPos, int number)
{
if (source.Length != target.Length)
throw new IndexOutOfRangeException("The source and target arrays must have the same number of elements.");
for (int ctr = startPos; ctr <= startPos + number - 1; ctr++)
target[ctr] = source[ctr];
}
}
open System
let copyStrings (source: string []) (target: string []) startPos number =
if source.Length <> target.Length then
raise (IndexOutOfRangeException "The source and target arrays must have the same number of elements.")
for i = startPos to startPos + number - 1 do
target.[i] <- source.[i]
let ordinals =
[| "First"; "Second"; "Third"; "Fourth"; "Fifth"
"Sixth"; "Seventh"; "Eighth"; "Ninth"; "Tenth" |]
let copiedOrdinals: string [] = Array.zeroCreate ordinals.Length
let copyOperation = Action<_, _, _, _> (fun s1 s2 pos num -> copyStrings s1 s2 pos num)
copyOperation.Invoke(ordinals, copiedOrdinals, 3, 5)
for ordinal in copiedOrdinals do
printfn "%s" (if String.IsNullOrEmpty ordinal then "<None>" else ordinal)
Public Module TestLambdaExpression
Public Sub RunIt()
Dim ordinals() As String = {"First", "Second", "Third", "Fourth", "Fifth",
"Sixth", "Seventh", "Eighth", "Ninth", "Tenth"}
Dim copiedOrdinals(ordinals.Length - 1) As String
Dim copyOperation As Action(Of String(), String(), Integer, Integer) =
Sub(s1, s2, pos, num) CopyStrings(s1, s2, pos, num)
copyOperation(ordinals, copiedOrdinals, 3, 5)
Console.WriteLine()
For Each ordinal As String In copiedOrdinals
If String.IsNullOrEmpty(ordinal) Then
Console.WriteLine("<None>")
Else
Console.WriteLine(ordinal)
End If
Next
End Sub
Private Function CopyStrings(source() As String, target() As String,
startPos As Integer, number As Integer) As Integer
If source.Length <> target.Length Then
Throw New IndexOutOfRangeException("The source and target arrays must have the same number of elements.")
End If
For ctr As Integer = startPos To startPos + number - 1
target(ctr) = source(ctr)
Next
Return number
End Function
End Module
' The example displays the following output:
' Fourth
' Fifth
' Sixth
' Seventh
' Eighth
擴充方法
GetMethodInfo(Delegate) |
取得表示特定委派所代表之方法的物件。 |
適用於
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