Powershell: Intellisense for `New-Object`'s `ComObject` parameterset

[mburszley]

Summary of the new feature/enhancement

Following the release of v7.preview3, there was a blog post showcasing the support of COM objects displaying their method argument names now.

https://devblogs.microsoft.com/powershell/powershell-7-preview-3/

Going further, it would be fantastic if the New-Object cmdlet had intellisense for its COM parameter set like what exists for the TypeName parameter set instead of completing from the PWD. It is a common scenario that I have to run registry queries to see which COM classes are available.

Proposed technical implementation details (optional)

New-Object -ComObject Shell.App<TAB>

Also <C-SPACE> for all options.

[HumanEquivalentUnit]

As a user-side / workaround, it's possible to add them with Register-ArgumentCompleter as in this profile script; line 13 collects and stores them in a cache file, line 74 adds completion for New-Object -ComObject parameter.

[mburszley]

Posting that here shortened as a form of documentation:

if (-not (Test-Path $PSScriptRoot\Cache\CompletionCache.ps1xml)) {
    [void](New-Item -Path $PSScriptRoot\Cache -ItemType Directory)

    Get-CimInstance -ClassName Win32_ClassicCOMClassSetting -Filter 'VersionIndependentProgId IS NOT NULL' |
        Select-Object -Property @(
            @{L='ProgId'; E={ $_.VersionIndependentProgId }}
            @{L='Caption'; E={ ($_.VersionIndependentProgId, $_.Caption)[!!$_.Caption] }}
        ) | Export-CliXml $PSScriptRoot\Cache\CompletionCache.ps1xml
}

$script:completionCache = Import-CliXml $PSScriptRoot\Cache\CompletionCache.ps1xml

Register-ArgumentCompleter -CommandName New-Object -ParameterName ComObject -ScriptBlock {
    param(
        [string]
        $CommandName,

        [string]
        $ParameterName,

        [string]
        $WordToComplete,

        [System.Management.Automation.Language.CommandAst]
        $CommandAst,

        [System.Collections.IDictionary]
        $FakeBoundParameters
    )

    $script:completionCache.Where{ $_.ProgId -like "$WordToComplete*" }.ForEach{
        [Management.Automation.CompletionResult]::new($_.ProgId, $_.ProgId, 'Type', $_.Caption)
    }
}

[lzybkr]

TabExpansionPlusPlus also implements this completion, see this file. Note that many of the other completers in that file should be added to PowerShell.

It's also worth mentioning that having a generic caching mechanism for completions like you'd want for -ComObject would be a valuable addition.