powershell - スマートパラメータを備えたPowershell関数

Answer 1

There may be more elegant methods, but you could do something like this:
1. Append "*" to your parameter value and use Test-Path against it. In this case, you're treating it like a folder, therefore c:\test would become c:\test\*.
2a. If Test-Path returns true, you have a folder and can proceed with copying its content.
2b. If Test-Path returns false, go to step 3.
3. Use Test-Path against the parameter as it is. If it returns true, then it is a file.

Update
Actually, it's much simpler than I thought. You can use parameter PathType with TestPath and specify if you're looking for a folder or a file.
- PathType Container will look for a folder.
- PahType Leaf will look for a file.

Answer 2

I'd determine if it's a text file or a folder and go from there. The function below should get you started and after the script has been run it can be executed like Copy-Thing -filename "sourcefile.txt" -Destination "C:\place"

Function Copy-Thing([string]$fileName,[string]$destination){
    $thing = Get-Item $fileName
    if ($thing.Extension -eq ".txt"){
        Get-Content | %{
            Copy-Item -Path $_ -Destination $destination
        }
    }
    elseif ($thing.PSIsContainer){
        Get-ChildItem -Path $fileName | %{
            Copy-Item -Path $_.FullName -Destination $destination
        }
    }
    else{
        Write-Host "Please specifiy a valid filetype (.txt) or folder"
    }
}