How to de-duplicate code in script block?

Question

New to Powershell. I am writing a script that watches files in a directory and reports the changes to the console.

I am noticing quite a bit of code duplication in the script blocks I'm using for the FS "watchers".

Here is a snippet of the script blocks. I can post the whole script if needed, it's a little longer and there's a little more going on.

# Filter all files
$filter = "*.*"
$watcher = New-Object IO.FileSystemWatcher $watchdir, $filter -Property @{
    IncludeSubdirectories = $true
    EnableRaisingEvents = $true
}

# File creation
Register-ObjectEvent $watcher Created -SourceIdentifier Created -Action {
    $path = $Event.SourceEventArgs.FullPath
    $name = $Event.SourceEventArgs.Name
    $changeType = $Event.SourceEventArgs.ChangeType
    $timeStamp = $Event.TimeGenerated
    $message = "The file '$name' was '$changeType' at '$timeStamp'"
    Write-Host $message
}

# File change
Register-ObjectEvent $watcher Changed -SourceIdentifier Changed -Action {
    $path = $Event.SourceEventArgs.FullPath
    $name = $Event.SourceEventArgs.Name
    $changeType = $Event.SourceEventArgs.ChangeType
    $timeStamp = $Event.TimeGenerated
    $message = "The file '$name' was '$changeType' at '$timeStamp'"
    Write-Host $message
}

# File rename
...

# File delete
...

Is there a good pattern or nicer way of writing this to reduce the amount of code?

Answer 1

In your examples, the script blocks are exactly the same, so in that case, just put them in a variable and pass that along:

$action = {
    $path = $Event.SourceEventArgs.FullPath
    $name = $Event.SourceEventArgs.Name
    $changeType = $Event.SourceEventArgs.ChangeType
    $timeStamp = $Event.TimeGenerated
    $console_message = "The file '$name' was '$changeType' at '$timeStamp'"
    Write-Host message
}

# File creation
Register-ObjectEvent $watcher Created -SourceIdentifier Created -Action $action

# File change
Register-ObjectEvent $watcher Changed -SourceIdentifier Changed -Action $action

If you post an example where there is redundancy in the script blocks but they aren't exactly the same, then it would be easier to show an example of how to best abstract that. There may not be a one-size-fits-all solution.