file IO, is this a bug in Powershell? - powershell

Question

I have the following code in Powershell
$filePath = "C:\my\programming\Powershell\output.test.txt"
try
{
$wStream = new-object IO.FileStream $filePath, [System.IO.FileMode]::Append, [IO.FileAccess]::Write, [IO.FileShare]::Read
$sWriter = New-Object System.IO.StreamWriter $wStream
$sWriter.writeLine("test")
}
I keep getting error:
Cannot convert argument "1", with value: "[IO.FileMode]::Append", for
"FileStream" to type "System.IO.FileMode": "Cannot convert value
"[IO.FileMode]::Append" to type "System.IO.FileMode" due to invalid
enumeration values. Specify one of the following enumeration values
and try again. The possible enumeration values are "CreateNew, Create,
Open, OpenOrCreate, Truncate, Append"."
I tried the equivalent in C#,
FileStream fStream = null;
StreamWriter stWriter = null;
try
{
fStream = new FileStream(#"C:\my\programming\Powershell\output.txt", FileMode.Append, FileAccess.Write, FileShare.Read);
stWriter = new StreamWriter(fStream);
stWriter.WriteLine("hahha");
}
it works fine!
What's wrong with my powershell script? BTW I am running on powershell
Major Minor Build Revision
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3 2 0 2237

Answer 1

Another way would be to use just the name of the value and let PowerShell cast it to the target type:
New-Object IO.FileStream $filePath ,'Append','Write','Read'

Answer 2

When using the New-Object cmdlet and the target type constructor takes in parameters, you should either use the -ArgumentList parameter (of New-Object) or wrap the parameters in parenthesis - I prefer to wrap my constructors with parens:
# setup some convenience variables to keep each line shorter
$path = [System.IO.Path]::Combine($Env:TEMP,"Temp.txt")
$mode = [System.IO.FileMode]::Append
$access = [System.IO.FileAccess]::Write
$sharing = [IO.FileShare]::Read
# create the FileStream and StreamWriter objects
$fs = New-Object IO.FileStream($path, $mode, $access, $sharing)
$sw = New-Object System.IO.StreamWriter($fs)
# write something and remember to call to Dispose to clean up the resources
$sw.WriteLine("Hello, PowerShell!")
$sw.Dispose()
$fs.Dispose()
New-Object cmdlet online help: http://go.microsoft.com/fwlink/?LinkID=113355

Answer 3

Yet another way could be to enclose the enums in parens:
$wStream = new-object IO.FileStream $filePath, ([System.IO.FileMode]::Append), `
([IO.FileAccess]::Write), ([IO.FileShare]::Read)

Answer 4

If your goal is to write into a logfile or text file, then you could try the supported cmdlets in PowerShell to achieve this?
Get-Help Out-File -Detailed