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Suggestion :: Write-Verbose Behaviour when packaged in a module #3106
Description
When Write-Verbose is included in a function or cmdlet in a module file, it doesn't behave in the same way as it would had that function been written in the main script file. i.e.
# MyScript.ps1
[CmdletBinding()]
param()
function Invoke-Demo {
[CmdletBinding()]
param ([Parameter()][string]$Message)
process {Write-Verbose $Message}
}
Invoke-Demo 'This DOES show when I run ".\MyScript.ps1 -Verbose"'
Write-Verbose 'This DOES show when I run ".\MyScript.ps1 -Verbose"'Behaves differently to:
# MyModule.psm1
function Invoke-Demo {
[CmdletBinding()]
param ([Parameter()][string]$Message)
process {Write-Verbose $Message}
}# MyScript.ps1
[CmdletBinding()]
param()
Import-Module -Path '.\MyModule.psm1' -Force
Invoke-Demo 'This does NOT show when I run ".\MyScript.ps1 -Verbose"'
Write-Verbose 'This DOES show when I run ".\MyScript.ps1 -Verbose"'This seems counter intuitive, and overly complex to get write-verbose to function based on whether the script is being run with the verbose switch enabled.
Suggested Solution
Since there may be a design reason for this behaviour, it's likely best that any new behaviour be controlled explicitly. As such I'd suggest enabling Write-Verbose to function as desired by including a switch when importing the module; i.e.
Import-Module -Path '.\MyModule.psm1' -Force -InheritVerboseMore information here: https://developer42.wordpress.com/2017/02/04/powershell-suggestion-simplify-write-verbose-in-modules/
Reacted by Adam Daniel, Joey Piccola, Francis Thérien, Cy Rossignol, Michael Klement, Tres Finocchiaro, Florian Carrier, rudolfwalter, Eduard Georgiev, zett42 and 1 more
Activity
joeypiccola commentedon May 3, 2017
I hit this a few years back, was hoping it was figured out.
mklement0 commentedon Apr 7, 2018
It took a while to emerge, but this is actually the more fundamental issue discussed in #4568:
Inheritance of common parameters - not just
-Verbose, but notably also-WhatIf- via advanced functions relies on implicitly set local preference variables:A common parameter, such as
-Verbose, passed to an advanced function is function-internally automatically translated into an equivalent local preference variable_, such as$VerbosePreference.This inheritance mechanism ONLY works:
By contrast, a function from a different module cannot see the caller's local preference variable, due to how module scopes function fundamentally.
In short: the common-parameter inheritance mechanism is fundamentally broken for advanced functions across module scopes.
ThomasNieto commentedon Aug 18, 2023
Steven Bucher (@StevenBucher98) should this be closed as a duplicate/related to #4568?