How can I make a StreamReader Open/Read/Close process into a function - powershell

Question

In Powershell, I frequently use a StreamReader to iterate over files and read/manipulate text. Instead of constantly having to type a script similar to:
## StreamReader setup / file availability check
try {
## Create Stream Reader
$readStream = [System.IO.StreamReader]::new($Path)
## Do stuff ...
} finally {
$readStream.close()
}
How can I make the entire setup/open/close process into a function that I can call whenever I need to automate the 'Do Stuff' portion of my above code? I am aware of how to make functions but I cant figure out how to turn this into a usable function so I only have to write it and edit it once but can use many times.

Answer 1

This may not be the most elegant solution but it does work.
You have different Functions for each type of processing I just called my test Process-Stream.
Function Process-Stream {
Do {
$Line = $readStream.ReadLine()
"$Line"
} While ($readStream.EndOfStream -eq $False)
} #End Function Process-Stream
Next you have a function that does all of your setup and error processing for the Stream.
Function Get-Stream {
Param (
[Parameter(Mandatory=$True)]
[String] $SourcePath,
[Parameter(Mandatory=$True)]
[String] $ProcessFunction
)
try {
## Create Stream Reader
$readStream = [System.IO.StreamReader]::new(
"$SourcePath")
& $ProcessFunction
} finally {
$readStream.close()
}
} #End Function Get-Stream
Now you just call Get-Stream with the name of your processing function.
PS> Get-Stream -SourcePath "G:\Test\StreamIOTest.txt" -ProcessFunction Process-Stream
Line 1
Line 2
Line 3
Line 4
PS>
Note: the test text file I used had 4 lines. Don't forget you need to have the functions loaded!
Updated: I realized after I posted that I should have parameterized the file to be read and passed that into Get-Stream also.
HTH

Answer 2

Assuming that you want to process your text files line by line:
There's no need to deal with [System.IO.StreamReader] instances directly - you can use PowerShell's built-in features.
In the simplest case, if performance isn't paramount, combine Get-Content with ForEach-Object:
Get-Content $Path | ForEach-Object { <# Do Stuff with $_, the line at hand #> }
When performance matters, use a switch statement with the -File parameter:
switch -File $Path { Default { <# Do Stuff with $_, the line at hand #> } }