Converting strings to timespans, $PSItem in 'switch'? - powershell

Question

I have a bunch of strings, in the form of:
'3m 36s', '24m 38s', '59s'
, to be converted to timespans. My current "solution" is:
'3m 36s', '24m 38s', '59s' |ForEach-Object {
$s = 0
$m = 0
$h = 0
$PSItem.Split(' ') |ForEach-Object {
$item = $PSItem
switch ($PSItem[-1])
{
's'
{
$s = $item.TrimEnd('s')
}
'm'
{
$m = $item.TrimEnd('m')
}
'h'
{
$h = $item.TrimEnd('h')
}
Default
{
Write-Error 'Ooops...' -ErrorAction Stop
}
}
}
$timespan = New-TimeSpan -Hours $h -Minutes $m -Seconds $s
# ToString() is used just to get some easy to read output
$timespan.ToString()
}
While it seems to work for me, I have two issues with the above:
Is the general approach
ForEach -> Split(' ') -> ForEach -> switch
OK-ish? Are there any alternative/better ways of doing the conversion?
I tried using $PSItem in the switch
It seems that the switch construct has it's "own pipeline"
# $item = $PSItem
switch ($PSItem[-1])
{
's'
{
$PSItem
}
}
-- in the above $PSItem evaluates to 's'(, 'm', the value matched). What is actually going on? (internaly?)

Answer 1

I would take one ForEach loop out of things by performing that loop with the Switch command. Here's what I'd end up with:
'3m 36s', '59s', '24m 38s' |%{
$TSParams = #{}
Switch($_.Split()){
{$_[-1] -eq 's'}{$TSParams.Add('Seconds', ([int]$_.trim('s')))}
{$_[-1] -eq 'm'}{$TSParams.Add('Minutes', ([int]$_.trim('m')))}
{$_[-1] -eq 'h'}{$TSParams.Add('Hours', ([int]$_.trim('h')))}
}
New-TimeSpan #TSParams
}
For each string it creates an empty hashtable, then loops through each item of the Split() method, adding the appropriate time to the hashtable. Then it splats that to the New-TimeSpan command, and moves to the next item in the ForEach loop. I tried it locally and had some issues initially when the numbers did not cast as an int, and it tried to convert them to a DateTime, which is why I type cast them in the above code.