Debugging PowerShell - powershell

Question

I'm not certain what is wrong with this scriptlet.
I'm trying to break out functionality into several other functions (I have a programming background not a scripting one per se) and to me LOGICALLY the following should execute starting at the "main" function Test-SgnedMpsPackage, accepting the various optional parameters (the script is not yet complete) then when the function Check-Path is called, that is run, then work would resume in the original calling function.
Am I missing something here?
On a side note, how does one return a value to the calling function? a simple return?
function CheckPath($path)
{
if ( test-path -Path $path )
{ Write-Host "{0} confirmed to exist." -f $path }
else
{ Write-Host "{0} DOES NOT exis.\nPlease check and run the script again" -f $path }
exit { exit }
}
function Test-SignedMpsPackage
{
Param(
[string] $PkgSource,
[string] $SigSource,
[string] $Destination
)
Process
{
#Check that both files exist
Write-Host "Check for file existence..."
CheckPath($PkgSource)
CheckPath($SigSource)
#retrieve signatures from file
}
}

Answer 1

Unlike C, C++ or C# there is no "main" entry point function. Any script at the top level - outside of a function - executes. You have defined two functions above but you haven't called either one. You need to do something like this:
function Test-SignedMpsPackage
{
...
}
Test-SignedMpsPackage params
Also as mentioned by #Bill_Stewart, you call your defined functions just like you call PowerShell commands - arguments are space separated and you don't use parens except to evaluate an expression inside the parens.
As for returning a value from a function, any output (Output stream) not captured by assigning to a variable or being redirected to a file is automatically part of the function's output. So I would modify your CheckPath function to this:
function CheckPath($path)
{
if (Test-Path -Path $path) {
Write-Verbose "{0} confirmed to exist." -f $path
$true
}
else {
Write-Verbose "{0} DOES NOT exist.\nPlease check and run the script again" -f $path
$false
}
}
You can use Write-Host as you had before but sometimes, perhaps in a script, you don't want to see the extra output. That is where Write-Verbose comes in handy. Set $VerbosePreference = 'Continue' to see the verbose output.