How to call a script with unknown parameters - powershell

Question

I have a script that calls other scripts that other people manage. It's essentially a CI/CD script that gives users the ability to tap into the pipeline.
The issue I'm running into now is that I would like this calling script to implement a couple new parameters. However, the old scripts don't always implement those parameters.
If I call their script that doesn't implement the parameters, I get an error "A parameter cannot be found that matches parameter name 'newparameter'".
Is there a way to dynamically pass in a parameter so that it doesn't fail if the parameter doesn't exist? I don't mind if they don't implement it. It's a bonus parameter that they don't need to use.
Alternately, can I do something like a Get-Command for a custom .ps1 script, to get a list of accepted parameters? With that, I could confirm that a parameter is implemented before I pass it.

Answer 1

This might help you get started, you could use the Parser Class
to get all functions and it's parameters from a script, this answer shows a minimal reproduction. I'll leave it to you to investigate further.
Given myScript.ps1 that has these 3 functions:
function ExampleFunc {
param([int] $param1 = 123, [string] $param2)
}
function ExampleFunc2 {
param([object] $param3, [switch] $param4)
}
function ExampleFunc3 ($param5, [hashtable] $param6 = #{foo = 'var'}) {
}
You can use the ParseFile Method to get the AST, then you can use the .FindAll method to filter for all FunctionDefinitionAst and subsequently find all parameters filtering for all ParameterAst.
using namespace System.Management.Automation.Language
$ast = [Parser]::ParseFile('path\to\myScript.ps1', [ref] $null, [ref] $null)
$ast.FindAll({ $args[0] -is [FunctionDefinitionAst] }, $true) | ForEach-Object {
$out = [ordered]#{ Function = $_.Name }
$_.FindAll({ $args[0] -is [ParameterAst] }, $true) | ForEach-Object {
$out['ParameterName'] = $_.Name.VariablePath
$out['Type'] = $_.StaticType
$out['DefaultValue'] = $_.DefaultValue
[pscustomobject] $out
}
} | Format-Table
Above code would result in the following for myScript.ps1:
Function ParameterName Type DefaultValue
-------- ------------- ---- ------------
ExampleFunc param1 System.Int32 123
ExampleFunc param2 System.String
ExampleFunc2 param3 System.Object
ExampleFunc2 param4 System.Management.Automation.SwitchParameter
ExampleFunc3 param5 System.Object
ExampleFunc3 param6 System.Collections.Hashtable #{foo = 'var'}
The same could be accomplished using Get-Command:
(Get-Command 'fullpath\to\myScript.ps1').ScriptBlock.Ast.FindAll({
... same syntax as before ... }, $true # or $false for non-recursive search
)