Is there a function pointer or array of functions in PowerShell? - arrays

Question

I would like to do something like this. Index into an array of functions and apply the appropriate function for the desired loop index.
for ($i = 0; $i -lt 9; $i++)
{
$Fields[$i] = $Fields[$i] | $($FunctionTable[$i])
}
#F1..F9 are defined functions or rather filter functions
$FunctionTable = {F1},
{F2},
{F3},
{F4},
{F5},
{F6},
{F7},
{F8},
{F9}

Answer 1

Here's an example of how to do this using the call (&) operator.
# define 3 functions
function a { "a" }
function b { "b" }
function c { "c" }
# create array of 3 functioninfo objects
$list = #(
(gi function:a),
(gi function:b),
(gi function:c)
)
0, 1, 2 | foreach {
# call functions at index 0, 1 and 2
& $list[$_]
}
-Oisin
p.s. this means your pipeline should bve amended to something like:
$Fields[$i] = $Fields[$i] | & $FunctionTable[$i]

Answer 2

Here is something similar also using the & operator:
function f1
{ "Exec f1" }
function f2
{ "Exec f2" }
function f3
{ "Exec f3" }
function f4
{ "Exec f4" }
function UseFunctionList ( [string[]]$FunctionList )
{
foreach ( $functionName in $functionList )
{
& $FunctionName
}
}
function Go
{
'List 1'
$FunctionList = 'f1','f2','f3','f4'
UseFunctionList $FunctionList
'List 2'
$FunctionList = 'f4','f3','f2'
UseFunctionList $FunctionList
}