Question

I ran into a snag when I passed a hash table by reference to a function for splatting purposes. How can I fix this?

Function AllMyChildren {
    param (
        [ref]$ReferenceToHash
    }
    get-childitem @ReferenceToHash.Value
    #  etc.etc.
}
$MyHash = @{
    'path' = '*'
    'include' = '*.ps1'
    'name' = $null
}
AllMyChildren ([ref]$MyHash)

Result: an error (“Splatted variables cannot be used as part of a property or array expression. Assign the result of the expression to a temporary variable then splat the temporary variable instead.”).

Tried to do this:

$newVariable = $ReferenceToHash.Value
get-childitem @NewVariable

That did work and seemed right per the error message. Is it the preferred syntax in a case like this?

Answer 1

1) Passing hashtables (or any instances of classes, i.e. reference types) with [ref] makes no sense because they are always passed by reference themselves. [ref] is used with value types (scalars and instances of structures).

2) The splatting operator can be applied to a variable directly, not an expression.

Thus, in order to resolve the problem simply pass the hashtable in the function as it is:

Function AllMyChildren {
    param (
        [hashtable]$ReferenceToHash # it is a reference itself
    )
    get-childitem @ReferenceToHash
    #  etc.etc.
}
$MyHash = @{
    'path' = '*'
    'include' = '*.ps1'
    'name' = $null
}
AllMyChildren $MyHash