PowerTip of the DayAcessing Function Parameters by Type

原文地址：

http://app.en25.com/e/es.aspx?s=1403&e=5125&elq=52bc48204cc748d58a54ab9a57b6b796

原文：

Adding parameters to your functions is fairly easy. You can add a param() block and specify the parameters. But what if you wanted to assign values to different parameters based solely on type? Let's say you want a function that accepts both numbers and text, and depending on which type you submitted, choose a parameter. Here is how you can do that:

function Test-Binding {
  [CmdletBinding(DefaultParameterSetName='Name')]
  param(
    [Parameter(ParameterSetName='ID', Position=0, Mandatory=$true)]
     [Int]
     $id,
    [Parameter(ParameterSetName='Name', Position=0, Mandatory=$true)]
     [String]
     $name
  )
 
 
  $set = $PSCmdlet.ParameterSetName
  "You selected parameterset $set"
 
  if ($set -eq 'ID') {
    "The numeric ID is $id"
  } else {
    "You entered $name as a name"
  }
}

Try this:

Test-Binding 12

Test-Binding "Hello"

Test-Binding

翻译：

方法里添加参数是很简单的。你可以在Param()代码块里添加指定的参数。但是如果想根据参数的类型来选择参数值到底赋给哪个参数呢？假如，有一个方法可以接收两个参数：Numbers和Text，根据你提交的内容，选择哪个参数，以下是实现方法：

function Test-Binding {
  [CmdletBinding(DefaultParameterSetName='Name')]
  param(
    [Parameter(ParameterSetName='ID', Position=0, Mandatory=$true)]
     [Int]
     $id,
    [Parameter(ParameterSetName='Name', Position=0, Mandatory=$true)]
     [String]
     $name
  )
 
 
  $set = $PSCmdlet.ParameterSetName
  "You selected parameterset $set"
 
  if ($set -eq 'ID') {
    "The numeric ID is $id"
  } else {
    "You entered $name as a name"
  }
}

调用方法：

Test-Binding 12

Test-Binding "Hello"

Test-Binding

笔记：

这个方法适用于动态参数的赋值，前提是参数的类型必须都不相同，否则会有歧义。