Functions/Use-CallerPreference.ps1
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function Use-CallerPreference { <# .SYNOPSIS Sets the PowerShell preference variables in a module's function based on the callers preferences. .DESCRIPTION Script module functions do not automatically inherit their caller's variables, including preferences set by common parameters. This means if you call a script with switches like `-Verbose` or `-WhatIf`, those that parameter don't get passed into any function that belongs to a module. When used in a module function, `Use-CallerPreference` will grab the value of these common parameters used by the function's caller: * ErrorAction * Debug * Confirm * InformationAction * Verbose * WarningAction * WhatIf This function should be used in a module's function to grab the caller's preference variables so the caller doesn't have to explicitly pass common parameters to the module function. This function is adapted from the [`Get-CallerPreference` function written by David Wyatt](https://gallery.technet.microsoft.com/scriptcenter/Inherit-Preference-82343b9d). There is currently a [bug in PowerShell](https://connect.microsoft.com/PowerShell/Feedback/Details/763621) that causes an error when `ErrorAction` is implicitly set to `Ignore`. If you use this function, you'll need to add explicit `-ErrorAction $ErrorActionPreference` to every `Write-Error` call. Please vote up this issue so it can get fixed. .LINK about_Preference_Variables .LINK about_CommonParameters .LINK https://gallery.technet.microsoft.com/scriptcenter/Inherit-Preference-82343b9d .LINK http://powershell.org/wp/2014/01/13/getting-your-script-module-functions-to-inherit-preference-variables-from-the-caller/ .EXAMPLE Use-CallerPreference -Cmdlet $PSCmdlet -SessionState $ExecutionContext.SessionState Demonstrates how to set the caller's common parameter preference variables in a module function. #> [CmdletBinding()] param ( [Parameter(Mandatory)] #[Management.Automation.PSScriptCmdlet] # The module function's `$PSCmdlet` object. Requires the function be decorated with the `[CmdletBinding()]` # attribute. $Cmdlet, [Parameter(Mandatory)] # The module function's `$ExecutionContext.SessionState` object. Requires the function be decorated with the # `[CmdletBinding()]` attribute. # # Used to set variables in its callers' scope, even if that caller is in a different script module. [Management.Automation.SessionState]$SessionState ) Set-StrictMode -Version 'Latest' # List of preference variables taken from the about_Preference_Variables and their common parameter name (taken # from about_CommonParameters). $commonPreferences = @{ 'ErrorActionPreference' = 'ErrorAction'; 'DebugPreference' = 'Debug'; 'ConfirmPreference' = 'Confirm'; 'InformationPreference' = 'InformationAction'; 'VerbosePreference' = 'Verbose'; 'WarningPreference' = 'WarningAction'; 'WhatIfPreference' = 'WhatIf'; } foreach( $prefName in $commonPreferences.Keys ) { $parameterName = $commonPreferences[$prefName] # Don't do anything if the parameter was passed in. if( $Cmdlet.MyInvocation.BoundParameters.ContainsKey($parameterName) ) { continue } $variable = $Cmdlet.SessionState.PSVariable.Get($prefName) # Don't do anything if caller didn't use a common parameter. if( -not $variable ) { continue } if( $SessionState -eq $ExecutionContext.SessionState ) { Set-Variable -Scope 1 -Name $variable.Name -Value $variable.Value -Force -Confirm:$false -WhatIf:$false } else { $SessionState.PSVariable.Set($variable.Name, $variable.Value) } } } |