{Core} Proof of concept for PowerShell argument completion

[tibortakacs]

Resolve #2324

Require kislyuk/argcomplete#302

This is a proof of concept implementation of Azure CLI argument completion in PowerShell.

Not ready to be merged.

It is based on this approach, please find the details there:
https://github.com/tibortakacs/powershell-argcomplete

How to use:

• Install Azure CLI on the normal way.
• . az.completion.ps1 (Dot source the completion script).
• Use tab or ctrl+space to invoke argument completion on PowerShell.

[yonzhan]

Nice PoC to support PowerShell argument completion

[jiasli]

+ Azure PowerShell owner of auto-complete @isra-fel

[jiasli]

FYI, this is the corresponding Bash script to enable auto-complete using argcomplete:

$ register-python-argcomplete az

# Run something, muting output or redirecting it to the debug stream
# depending on the value of _ARC_DEBUG.
__python_argcomplete_run() {
    if [[ -z "$_ARC_DEBUG" ]]; then
        "$@" 8>&1 9>&2 1>/dev/null 2>&1
    else
        "$@" 8>&1 9>&2 1>&9 2>&1
    fi
}

_python_argcomplete() {
    local IFS=$'\013'
    local SUPPRESS_SPACE=0
    if compopt +o nospace 2> /dev/null; then
        SUPPRESS_SPACE=1
    fi
    COMPREPLY=( $(IFS="$IFS" \
                  COMP_LINE="$COMP_LINE" \
                  COMP_POINT="$COMP_POINT" \
                  COMP_TYPE="$COMP_TYPE" \
                  _ARGCOMPLETE_COMP_WORDBREAKS="$COMP_WORDBREAKS" \
                  _ARGCOMPLETE=1 \
                  _ARGCOMPLETE_SUPPRESS_SPACE=$SUPPRESS_SPACE \
                  __python_argcomplete_run "$1") )
    if [[ $? != 0 ]]; then
        unset COMPREPLY
    elif [[ $SUPPRESS_SPACE == 1 ]] && [[ "$COMPREPLY" =~ [=/:]$ ]]; then
        compopt -o nospace
    fi
}
complete -o nospace -o default -o bashdefault -F _python_argcomplete az

[isra-fel]

An idea about how to enable autocomplete on startup: we can tell the user to add a line to their powershell profile, to be specific:

1. Edit $PROFILE (this is a powershell variable that points to the actual url of the profile file), append a line: . az.completion.ps1

And I think a more official(pro) way is to publish this as a powershell module for example AzCliUtil, and expose this function as a cmdlet such as "Enable-AzCliAutoComplete". In this case customers will need to:

1. Install-Module AzCliUtil
2. Edit $PROFILE, append a line Enable-AzCliAutoComplete

[isra-fel]

If Invoke-Expression failed, $completionResult will not have a Split() method and will error out.

[tibortakacs]

Valid point. However, PowerShell argument completion engine hides all error, but you are right, it is better to cause any unexpected error. I have added a simple check there.

[itpropro]

Hi,
Any updates on this issue/PR?

[SteveL-MSFT]

There's no need to use Invoke-Expression here, instead, you should use:

Suggested change

	Invoke-Expression $AzCommand -OutVariable completionResult -ErrorVariable errorOut -ErrorAction SilentlyContinue | Out-Null
	$completionResult = & $AzCommand

[SteveL-MSFT]

This comment is no longer applicable with the larger comment above, but leaving here as informing when not to use Invoke-Expression

[SteveL-MSFT]

Very interesting approach, some rework on the PowerShell side of things

[SteveL-MSFT]

This is a very creative approach using the bash completer, however, since these env vars are for the process and gets inherited by az and then removed, it would be better to use .NET API to start the process and leveraging https://docs.microsoft.com/en-us/dotnet/api/system.diagnostics.processstartinfo.environmentvariables?view=net-6.0#system-diagnostics-processstartinfo-environmentvariables

It would look something like:

$env = @{
  _ARGCOMPLETE = 1
  COMP_TYPE = 9
  _ARGCOMPLETE_IFS = " "
}

$psi = [System.Diagnostics.ProcessStartInfo]::new($AzCommand)
$psi.RedirectStandardError = $true
$psi.RedirectStandardOutput = $true

foreach ($var in $env.keys) {
  $psi.Environment.Add($var, $env.$var)
}

$az = [System.Diagnostics.Process]::Start($psi)
$az.Start()
$az.WaitForExit()
$completionResult = $az.StandardOutput.ReadToEnd()

[SteveL-MSFT]

This comment is no longer applicable with the larger comment above, but leaving here as informing when not to use Invoke-Expression

[SteveL-MSFT]

This whole script should probably be in a Enable-AzCompletion cmdlet and shouldn't be repeated in both a ps1 and psm1

[mgreenegit]

Thank you for this contribution @tibortakacs. Please see the feedback above.

[mgreenegit]

Following up @tibortakacs
Thank you!