.net - Powershell function parameter type System.ConsoleColor - Missing ')' in function parameter list

Question

I'm trying to create a cmdlet function in powershell with 2 arguments. I want one of those 2 arguments to be a ConsoleColor but ISE complains and says there is a Missing ')' in function parameter list. But I can't find this missing ).

Here is my function:

function Log {
    [CmdletBinding()]
    param (
        [Parameter(ValueFromPipeline=$true, ValueFromRemainingArguments=$true)]
        [AllowNull()]
        [AllowEmptyString()]
        [AllowEmptyCollection()]
        [string[]]$messages,

        # If I remove the following parameter, everything works fine
        [System.ConsoleColor]$color = Default # ISE Complains here before `=`
    )

    if (($messages -eq $null) -or ($messages.Length -eq 0)) {
        $messages = @("")
    }

    foreach ($msg in $messages) {
        Write-Host $msg -ForegroundColor $color
        $msg | Out-File $logFile -Append
    }
}

I'm not very good in powershell so it might be something stupid that I just don't know yet.

标签： .netfunctionpowershellcmdlet

Answer 1

The issue has been pointed out in the comments. You can't just assign something called Default as your parameter's default value.

Since that enum doesn't have a "default" value, I'll suggest a different approach.

Don't use a default value for the parameter, then either use a conditional (bleh) or splatting (super cool) to handle that:

Conditional

function Log {
    [CmdletBinding()]
    param (
        [Parameter(ValueFromPipeline=$true, ValueFromRemainingArguments=$true)]
        [AllowNull()]
        [AllowEmptyString()]
        [AllowEmptyCollection()]
        [string[]]$messages,

        [System.ConsoleColor]$color
    )

    if (($messages -eq $null) -or ($messages.Length -eq 0)) {
        $messages = @("")
    }

    foreach ($msg in $messages) {
        if ($color) {
            Write-Host $msg -ForegroundColor $color
        } else {
            Write-Host $msg
        }
        $msg | Out-File $logFile -Append
    }
}

Splatting

function Log {
    [CmdletBinding()]
    param (
        [Parameter(ValueFromPipeline=$true, ValueFromRemainingArguments=$true)]
        [AllowNull()]
        [AllowEmptyString()]
        [AllowEmptyCollection()]
        [string[]]$messages,

        [System.ConsoleColor]$color
    )

    $params = @{}
    if ($color) {
        $params.ForegroundColor = $color
    }

    if (($messages -eq $null) -or ($messages.Length -eq 0)) {
        $messages = @("")
    }

    foreach ($msg in $messages) {
        Write-Host $msg @params

        $msg | Out-File $logFile -Append
    }
}