Delay-bind script-block information is partially incorrect

[mklement0]

The about_Parameters, about_Functions_Advanced_Parameters and about_Script_Blocks topics state:

The former two:

A parameter that accepts pipeline input (by Value) will enable use of delay-bind script blocks on all other parameters defined to accept pipeline input.

The latter:

A delay-bind script block allows you to pipe input to a given parameter, then use script blocks for other parameters using the pipeline variable $_ to reference the same object.

This is incorrect in two respects:

• It is not necessary for multiple pipeline-binding parameters to be present - one is enough.
• Specifically, there is no requirement that a by-value (as opposed to by-property-name) parameter be present.

In short: While it may be the typical uses case that the pipeline input binds to a by-value parameter and that additional parameters may be bound by delay-bind script blocks, that is not a requirement.

Here's an example:

'foo', 'bar' | & {
  param(
     [Parameter(ValueFromPipelineByPropertyName)]
     [string] $Text
  )
  process {
    "[$Text]"
  }
} -Text { $_ + '!' }

The above yields:

[foo!]
[bar!]

which showsthat a single, by-property-name pipeline-binding parameter is sufficient to support delay-binding.

Version(s) of document impacted

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