powershell 数组的方法（Clear、ForEach、Where 等）在哪里定义？

Question

根据offical documentPowerShell中关于数组的介绍，为数组定义了几种方法，例如Clear()、ForEach()、Where()等。以下代码测试了这些方法：

$arr = 1..2
$arr.Clear()
$arr.Length

write "--------------------------------------------------"
$arr = 1..2
$arr.ForEach({$_ + 1})

write "--------------------------------------------------"
$arr = 65..90
$arr.Where({($_ % 2) -eq 0})

输出：

2
--------------------------------------------------
2
3
--------------------------------------------------
66
68
70
72
74
76
78
80
82
84
86
88
90

很好！并且，诸如 ForEach() 之类的方法有许多未在此处测试的重载。

但是这些方法是在哪里定义的呢？我的意思是，包含这些方法定义的 class 是什么？据我所知，.net core 中没有定义这些方法。（我使用 PowerShell 7）

Answer 1

Clear() 是 System.Array 实现的 IList 接口的一部分，它是 PowerShell 中集合 (System.Object[]) 的基本类型。

要查看所有可用的本机方法，请使用：

$arr.PSObject.Methods
# or
Get-Member -InputObject $arr -MemberType Methods

但是： Where() 和 ForEach() "magic" methods were introduced in v4 and are actually PowerShell-specific extension methods (as more performant alternatives to ForEach-Object and Where-Object), defined in System.Management.Automation.EnumerableOps. Have a look at the source:

internal static object Where(IEnumerator enumerator, ScriptBlock expressionSB, WhereOperatorSelectionMode selectionMode, int numberToReturn)

internal static object ForEach(IEnumerator enumerator, object expression, object[] arguments)

Answer 2

为什么这么说据我所知，.net core 中没有定义这些方法。（我使用 PowerShell 7）？真的：

$PSVersionTable.PSVersion | Out-Default
$arr = 1..2
$arr.GetType() | Get-Member -MemberType Methods -Static

Major  Minor  Patch  PreReleaseLabel BuildLabel
-----  -----  -----  --------------- ----------
7      0      3


   TypeName: System.Object[]

Name            MemberType Definition
----            ---------- ----------
AsReadOnly      Method     static System.Collections.ObjectModel.ReadOnlyCollection[T] …
BinarySearch    Method     static int BinarySearch[T](T[] array, int index, int length,…
Clear           Method     static void Clear(array array, int index, int length)
ConstrainedCopy Method     static void ConstrainedCopy(array sourceArray, int sourceInd…
ConvertAll      Method     static TOutput[] ConvertAll[TInput, TOutput](TInput[] array,…
Copy            Method     static void Copy(array sourceArray, array destinationArray, …
CreateInstance  Method     static array CreateInstance(type elementType, int length), s…
Empty           Method     static T[] Empty[T]()
Equals          Method     static bool Equals(System.Object objA, System.Object objB)
Exists          Method     static bool Exists[T](T[] array, System.Predicate[T] match)
Fill            Method     static void Fill[T](T[] array, T value), static void Fill[T]…
Find            Method     static T Find[T](T[] array, System.Predicate[T] match)
FindAll         Method     static T[] FindAll[T](T[] array, System.Predicate[T] match)
FindIndex       Method     static int FindIndex[T](T[] array, System.Predicate[T] match…
FindLast        Method     static T FindLast[T](T[] array, System.Predicate[T] match)
FindLastIndex   Method     static int FindLastIndex[T](T[] array, System.Predicate[T] m…
ForEach         Method     static void ForEach[T](T[] array, System.Action[T] action)
IndexOf         Method     static int IndexOf(array array, System.Object value), static…
LastIndexOf     Method     static int LastIndexOf(array array, System.Object value), st…
new             Method     System.Object[] new(int )
ReferenceEquals Method     static bool ReferenceEquals(System.Object objA, System.Objec…
Resize          Method     static void Resize[T]([ref] T[] array, int newSize)
Reverse         Method     static void Reverse(array array), static void Reverse(array …
Sort            Method     static void Sort(array array), static void Sort(array keys, …
TrueForAll      Method     static bool TrueForAll[T](T[] array, System.Predicate[T] mat…

powershell 数组的方法（Clear、ForEach、Where 等）在哪里定义？

Where methods (Clear, ForEach, Where, etc.) of powershell array are defined?

arrays

powershell

powershell-core