[英]Declare get accessors in PowerShell cmdlet parameters
"Parameters must be declared on public non-static fields or properties. Parameters should be declared on properties. The property must have a public set accessor, and if the ValueFromPipeline or ValueFromPipelineByPropertyName keyword is specified, the property must have a public get accessor."
“必须在公共非静态字段或属性上声明参数。应在属性上声明参数。该属性必须具有公共集访问器,如果指定了ValueFromPipeline或ValueFromPipelineByPropertyName关键字,则该属性必须具有公共get访问器。”
Why do I have to declare get accessors in my cmdlet ValueFromPipeline
parameters? 为什么我必须在我的cmdlet
ValueFromPipeline
参数中声明get访问器? As far as I know, PowerShell only needs to put their values in, not read them out. 据我所知,PowerShell只需要将它们的值放入,而不是将它们读出来。 Thanks (by the way im just curious about this behavior :) ).
谢谢(顺便说一句,我只是好奇这个行为:))。
PowerShell reads the default value of the parameters marked with ValueFromPipeline
or ValueFromPipelineByPropertyName
to make a backup before assigning the new value obtained from the pipeline . PowerShell 在分配从管道获取的新值之前, 读取使用
ValueFromPipeline
或ValueFromPipelineByPropertyName
标记的参数的默认值以进行备份。
Consider the following cmdlets: 请考虑以下cmdlet:
New-Post -Title <string>
Set-Post -InputObject <Post> -Title <string>
where the following applies: 以下适用情况:
New-Post
cmdlet returns the newly created Post
object to the pipeline, which has a Title
property New-Post
cmdlet 将新创建的Post
对象返回到具有 Title
属性的管道 InputObject
property on the Set-Post
cmdlet is marked with ValueFromPipeline = true
Set-Post
cmdlet上的InputObject
属性标记为ValueFromPipeline = true
Title
property on the Set-Post
cmdlet is marked with ValueFromPipelineByPropertyName = true
. Set-Post
cmdlet上的Title
属性标记为ValueFromPipelineByPropertyName = true
。 Combining them with the following command: 将它们与以下命令结合使用:
New-Post -Title "Foo" | Set-Post
and setting a breakpoint on the get accessor of the Set-Post
cmdlet's Title
property results in the following stack trace: 并在
Set-Post
cmdlet的Title
属性的get访问器上设置断点会产生以下堆栈跟踪:
As you can see, the CmdletParameterBinderController.GetDefaultParameterValue
method is invoked during the process of binding the Title
property on the Set-Post
cmdlet with the value from the corresponding property on the object coming from the pipeline. 如您所见,在将
Set-Post
cmdlet上的Title
属性与来自管道的对象上的相应属性的值绑定的过程中,将调用CmdletParameterBinderController.GetDefaultParameterValue
方法。
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