Validate RegEx pattern in PowerShell

Is it possible to validate pattern before creating RegEx object in PowerShell?

$Pattern = "[A-Z]{1,3" # Pattern is invalid
$Regex = [regex]::new($Pattern) # this throw an exception 

Let say that I have XML file with configuration and there are fields with pattern which will be used in the script. If pattern is not correct I’m getting an error which I would like to avoid.

>Solution :

If you want to avoid dealing with the exception (which you could do with try / catch, as Mathias shows in a comment), you can use the -as operator, which attempts conversion to a given RHS type, and quietly returns $null if that fails:

$valid = $null -ne ($regex = $pattern -as [regex])

• $valid then contains a Boolean ($true or $false) that indicates whether $pattern contains a valid regex.

• $regex then either contains a [regex] instance based on the pattern, or $null if the pattern isn’t valid.

  • If all you want to do is to validate the pattern itself, remove the $regex = part