When does Powershell honour default values when using $null splat parameters? -

consider following function:

function f1{     param(         $sb = {},         $s  = ''     )     if ($sb -isnot [scriptblock]) { 'scriptblock' }     if ($s  -isnot [string]     ) { 'string' } } 

now invoke splat parameter:

ps c:\> $splat = @{foo='bar'} ps c:\> f1 @splat 

as expected, nothing returned. try again $null splat parameter:

ps c:\> $splat = $null ps c:\> f1 @splat scriptblock 

oddly, scriptblock returned. clearly, @ least [scriptblock] parameter, powershell not honoring default value when $null splat parameter used. powershell honor default value [string]. going on here?

for types powershell honour default values when using $null splat parameters?

here's demonstration understand what's happening

$splat = @{foo='bar'} "$(&{$args}@splat)" -foo: bar 

when splat hash table, gets converted -key: value string pairs become parameters function.

now try:

$splat = $null "$(&{$args}@splat)" 

nothing returned. there no keys generate parameter string from, end result same not passing parameters @ all.