Default value of parameter is not used in function

Question

I have a very basic PowerShell script:

Param(
    [string]$MyWord
)

function myfunc([string] $MyWord) {
    Write-Host \"$MyWord\"
}
myfunc @PSBoundParamete         


        

Answer 1

A parameter is bound only if you actually pass it a value, meaning that a parameter's default value does not show up in $PSBoundParameters. If you want to pass script parameters into a function, you must replicate the script parameter set in the function parameter set:

Param(
    [string]$MyWord = 'hi'
)

function myfunc([string]$MyWord = 'hi') {
    Write-Host "$MyWord" 
}

myfunc @PSBoundParameters

Maintaining something like this is easier if you define both parameter sets the same way, though, so I'd put the function parameter definition in a Param() block as well:

Param(
    [string]$MyWord = 'hi'
)

function myfunc {
    Param(
        [string]$MyWord = 'hi'
    )

    Write-Host "$MyWord" 
}