Proxy for import-module
I do quite a lot with modules as you can tell from my posts over the last few months and have bit a fair collection of modules. One issue I find when loading a module is that I can’t always remember the name of the commands that the module creates. If we use
Import-Module -Name filefunctions
we just get the prompt returned and no information on the commands. After a bit of experimenting I found that
Import-Module -Name filefunctions -PassThru | foreach {Get-Command -Module $_.Name | select name}
will give me the list of commands added by a particular module. Instead of get-command I could have used
Get-Module filefunctions | select -ExpandProperty ExportedCommands
Rather than remembering to run the get-command I could have implemented a function that would run the commands. However, I thought it might be more fun to create a proxy command as detailed in these posts
http://blogs.msdn.com/powershell/archive/2009/01/04/extending-and-or-modifing-commands-with-proxies.aspx
http://blogs.msdn.com/powershell/archive/2009/01/05/ps-dir-a-d-the-screencast.aspx
I found the video in the second one irritating as it stopped every few seconds to ask if I wanted to continue watching.
Anyway we use the metaprogramming module that can be downloaded from the first post. This gives us a New-ProxyCommand function that we use like this.
New-ProxyCommand Import-Module -CommandType all -AddParameter ListMember > import-mymodule.ps1
The output script then has the code to execute the extra parameter inserted – the skeleton can be found in the block comment at the top of the script. To produce something like this
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| <# You are responsible for implementing the logic for added parameters. These parameters are bound to $PSBoundParameters so if you pass them on the the command you are proxying, it will almost certainly cause an error. This logic should be added to your BEGIN statement to remove any specified parameters from $PSBoundParameters. In general, the way you are going to implement additional parameters is by modifying the way you generate the $scriptCmd variable. Here is an example of how you would add a -SORTBY parameter to a cmdlet: ################################################################################ New ATTRIBUTES if ($ListMember) { [Void]$PSBoundParameters.Remove("ListMember") } ################################################################################ #>
[CmdletBinding(DefaultParameterSetName='Name')]
param(
[Switch]
${Global},
[ValidateNotNull()]
[System.String]
${Prefix},
[Parameter(ParameterSetName='Name', Mandatory=$true, Position=0, ValueFromPipeline=$true)]
[System.String[]]
${Name},
[Parameter(ParameterSetName='Assembly', Mandatory=$true, Position=0, ValueFromPipeline=$true)]
[System.Reflection.Assembly[]]
${Assembly},
[ValidateNotNull()]
[System.String[]]
${Function},
[ValidateNotNull()]
[System.String[]]
${Cmdlet},
[ValidateNotNull()]
[System.String[]]
${Variable},
[ValidateNotNull()]
[System.String[]]
${Alias},
[Switch]
${Force},
[Switch]
${PassThru},
[Switch]
${AsCustomObject},
[Parameter(ParameterSetName='Name')]
[System.Version]
${Version},
[Parameter(ParameterSetName='ModuleInfo', Mandatory=$true, Position=0, ValueFromPipeline=$true)]
[System.Management.Automation.PSModuleInfo[]]
${ModuleInfo},
[Alias('Args')]
[System.Object[]]
${ArgumentList},
[Switch]
${DisableNameChecking},
[Switch]
${ListMember})
begin
{
try {
$outBuffer = $null
if ($PSBoundParameters.TryGetValue('OutBuffer', [ref]$outBuffer))
{
$PSBoundParameters['OutBuffer'] = 1
}
$wrappedCmd = $ExecutionContext.InvokeCommand.GetCommand('Import-Module', [System.Management.Automation.CommandTypes]::Cmdlet)
if ($ListMember)
{
[Void]$PSBoundParameters.Remove("ListMember")
$scriptCmd = {& $wrappedCmd @PSBoundParameters | foreach {Get-Command -Module $_.Name | select name}}
}else
{
$scriptCmd = {& $wrappedCmd @PSBoundParameters }
}
$steppablePipeline = $scriptCmd.GetSteppablePipeline($myInvocation.CommandOrigin)
$steppablePipeline.Begin($PSCmdlet)
} catch {
throw
}
}
process
{
try {
$steppablePipeline.Process($_)
} catch {
throw
}
}
end
{
try {
$steppablePipeline.End()
} catch {
throw
}
}
<# .ForwardHelpTargetName Import-Module .ForwardHelpCategory Cmdlet #>
|
The important part is
if ($ListMember)
{
[Void]$PSBoundParameters.Remove("ListMember")
$scriptCmd = {& $wrappedCmd @PSBoundParameters | foreach {Get-Command -Module $_.Name | select name}}
}else
{
$scriptCmd = {& $wrappedCmd @PSBoundParameters }
}
where we add the extra code we need for the new parameter.
We can use the new script in place of import-module
PS> .\import-mymodule.ps1 filefunctions
PS> .\import-mymodule.ps1 filefunctions -Force
PS> .\import-mymodule.ps1 filefunctions -Force -PassThru -ListMember
Name
----
Format-Colorfile
Format-Xml
Get-EmptyFolder
Get-TempContents
New-TempFile
Remove-EmptyFolder
Remove-TempContents
Remove-ZoneIdentifier
Test-ZoneIdentifier
It is a simple task to make this a function that is loaded in the profile.
This isn’t a technique for everyone but if you feel comfortable experimenting like this give it a try. There must be a number of other cmdlets where we can modify the behaviour to add functionality to suit our individual needs.