PowerShell 3.0 应该有更清晰的语法，它是什么样的？

Question

我看到提到了改进的 PowerShell 3.0 语法，但还没有示例，它会是什么样子？

Answer 1

许多常见的*-Object cmdlet 利用多个参数集来完成简化的语法。在 V3 中看一下：

C:\PS> Get-Command Where-Object -Syntax

Where-Object [-Property] <string> [[-Value] <Object>] [-InputObject <psobject>] [-EQ] [<CommonParameters>]

Where-Object [-FilterScript] <scriptblock> [-InputObject <psobject>] [<CommonParameters>]

Where-Object [-Property] <string> [[-Value] <Object>] [-InputObject <psobject>] -CGT [<CommonParameters>]

Where-Object [-Property] <string> [[-Value] <Object>] [-InputObject <psobject>] -CNE [<CommonParameters>]

Where-Object [-Property] <string> [[-Value] <Object>] [-InputObject <psobject>] -LT [<CommonParameters>]

Where-Object [-Property] <string> [[-Value] <Object>] [-InputObject <psobject>] -CEQ [<CommonParameters>]

Where-Object [-Property] <string> [[-Value] <Object>] [-InputObject <psobject>] -NE [<CommonParameters>]

Where-Object [-Property] <string> [[-Value] <Object>] [-InputObject <psobject>] -GT [<CommonParameters>]

Where-Object [-Property] <string> [[-Value] <Object>] [-InputObject <psobject>] -CLT [<CommonParameters>]

Where-Object [-Property] <string> [[-Value] <Object>] [-InputObject <psobject>] -GE [<CommonParameters>]

Where-Object [-Property] <string> [[-Value] <Object>] [-InputObject <psobject>] -CGE [<CommonParameters>]

Where-Object [-Property] <string> [[-Value] <Object>] [-InputObject <psobject>] -LE [<CommonParameters>]

Where-Object [-Property] <string> [[-Value] <Object>] [-InputObject <psobject>] -CLE [<CommonParameters>]

Where-Object [-Property] <string> [[-Value] <Object>] [-InputObject <psobject>] -Like [<CommonParameters>]

Where-Object [-Property] <string> [[-Value] <Object>] [-InputObject <psobject>] -CLike [<CommonParameters>]

Where-Object [-Property] <string> [[-Value] <Object>] [-InputObject <psobject>] -NotLike [<CommonParameters>]

Where-Object [-Property] <string> [[-Value] <Object>] [-InputObject <psobject>] -CNotLike [<CommonParameters>]

Where-Object [-Property] <string> [[-Value] <Object>] [-InputObject <psobject>] -Match [<CommonParameters>]

Where-Object [-Property] <string> [[-Value] <Object>] [-InputObject <psobject>] -CMatch [<CommonParameters>]

Where-Object [-Property] <string> [[-Value] <Object>] [-InputObject <psobject>] -NotMatch [<CommonParameters>]

Where-Object [-Property] <string> [[-Value] <Object>] [-InputObject <psobject>] -CNotMatch [<CommonParameters>]

Where-Object [-Property] <string> [[-Value] <Object>] [-InputObject <psobject>] -Contains [<CommonParameters>]

Where-Object [-Property] <string> [[-Value] <Object>] [-InputObject <psobject>] -CContains [<CommonParameters>]

Where-Object [-Property] <string> [[-Value] <Object>] [-InputObject <psobject>] -NotContains [<CommonParameters>]

Where-Object [-Property] <string> [[-Value] <Object>] [-InputObject <psobject>] -CNotContains [<CommonParameters>]

Where-Object [-Property] <string> [[-Value] <Object>] [-InputObject <psobject>] -In [<CommonParameters>]

Where-Object [-Property] <string> [[-Value] <Object>] [-InputObject <psobject>] -CIn [<CommonParameters>]

Where-Object [-Property] <string> [[-Value] <Object>] [-InputObject <psobject>] -NotIn [<CommonParameters>]

Where-Object [-Property] <string> [[-Value] <Object>] [-InputObject <psobject>] -CNotIn [<CommonParameters>]

Where-Object [-Property] <string> [[-Value] <Object>] [-InputObject <psobject>] -Is [<CommonParameters>]

Where-Object [-Property] <string> [[-Value] <Object>] [-InputObject <psobject>] -IsNot [<CommonParameters>]

注意：查看新的运算符 -NotIn 和 -In 例如：

C:\PS> 1 -In 1..5
C:\PS> 10 -NotIn 1..5

因此简化的语法对于“常见”情况很好，但请注意因为你很容易掉进尖锐的岩石和熔岩中，例如：

C:\PS> Get-ChildItem | Where LastWriteTime.Year -eq 2010

这不会返回任何内容，更糟糕的是，没有错误，所以你认为结果集“正确”为空，而实际上这种语法并不像你那样工作可能会期待。也就是说，您无法访问属性的属性。在上面，PowerShell 查找名为 LastWriteTime.Year 的属性，该属性不存在。

另请注意，作为简化语法的一部分，您现在可以使用 $PSItem 代替 $_，以防您或您为其编写脚本的人对以下内容产生某种过敏反应： <代码>$_。 :-)

虽然这不一定与简化的语法相关，但我发现它简化了我的生活，而且我喜欢它：

C:\PS> Get-ChildItem -Directory
C:\PS> Get-ChildItem -File
C:\PS> dir -ad
C:\PS> Get-ChildItem -Attributes System+Hidden+Directory+!Archive

Answer 2

这是一个示例：

dir |其中 length -lt 10

在 3.0 之前，它会是

dir |其中 {$_.length -lt 10}

编辑：另一个例子，这次使用 foreach-object

dir | foreach-对象长度

Answer 3

Powershell 确实已经拥有相当干净的语法，因此没有太多需要改进的地方。

我喜欢的一项新功能是作为对象的哈希表，您可以通过传递 hastable 及其属性来创建对象：

[<ClassName>]$Variable = @{<Property>=<Value>;<Property>=<Value>}

因此，创建自定义对象的更新、更简洁的方法是：

$obj = [PSCustomObject]@{a=1; b=2; c=3; d=4}

重定向已加强了。除了正常（管道）和错误之外，您现在还拥有详细、调试和警告流，因此您可以执行诸如 5>&1 之类的重定向，

您可以使用 $PSDefaultParameterValues用于设置 cmdlet 的默认参数值的首选项变量。

有新的 [ordered] 加速器来创建有序的 hastable（字典）：

 $a = [ordered]@{a=1;b=2;d=3;c=4}

从 SO 中的另一个答案，我意识到 -in 是 Powershell v3.0 中的新功能：

所以你会做类似 1 -in 1,2,3 的事情。以前我们只有 -contains

Cmdlet：

您可以使用 Update-Help cmdlet 更新帮助。有一些与 Web 相关的 cmdlet，例如 Invoke-
Web请求。您还可以使用 ConverTo-JSON 和 ConvertFrom-JSON cmdlet 处理 JSON。