ValidateSet with 3001 elements causes long pause - powershell

Question

Here's a simple function that uses ValidateSet:
function TestLongValidateSet
{
param
(
[ValidateSet(...)]
$abc
)
$abc
}
My version has 3001 items instead of the ....
If you'd like to follow along at home, here's a way to generate a 3001 element list suitable for placing in there:
(0..3000 | foreach { (Get-Random -Count 30 (65..90 | ForEach-Object { [char]$_ })) -join '' } | ForEach-Object { "`"$_`"" }) -join ', ' | Out-File test.txt
Anyway, the above function loads into PowerShell just fine. However, the first attempt at using IntelliSense with it triggers a multi-minute delay. PowerShell ISE also proceeds to consume a couple of gigabytes of RAM. After this delay, the RAM usage drops back to normal, IntelliSense works, and everything's responsive. Even the completion on the $abc variable is responsive.
Is there anyway to avoid the long initial delay?

Answer 1

Try this. It creates a custom enum type, and uses that instead of ValidateSet
0..3000 | foreach { (Get-Random -Count 30 (65..90 | ForEach-Object { [char]$_ })) -join '' } | sv enumarray
$i=0
$enumlist = ($enumarray | foreach {'{0} = {1}' -f $_,$i++}) -join ', '
$enum = "
namespace myspace
{
public enum myenum
{
$enumlist
}
}
"
Add-Type -TypeDefinition $enum -Language CSharpVersion3
You can put that inside the function, but on my system, creating the enum takes about 200ms. If you're going to run this inside a loop, I'd create it in the parent scope so the function doesn't have to do it every time it runs.
function TestLongValidateSet
{
param
(
[myspace.myenum]$abc
)
$abc
}