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I've written function 'A' that will call one of a number of other functions. To save re-writing function 'A', I'd like to pass the function to be called as a parameter of function 'A'. For example:
function A{ Param($functionToCall) Write-Host "I'm calling : $functionToCall" } function B{ Write-Host "Function B" } Function C{ write-host "Function C" } A -functionToCall C Returns: I'm calling: C
I am expecting it to return: I'm calling: Function C.
I've tried various things such as:
Param([scriptblock]$functionToCall) Cannot convert System.String to ScriptBlock
A -functionToCall $function:C Returns "Write-Host "Function C"
A - functionToCall (&C) This evaluates before the rest of it:
Function C I'm Calling : I'm sure this is programming 101, but I can't work out the correct syntax or what it is I'm doing wrong.
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Because functions are objects we can pass them as arguments to other functions. Functions that can accept other functions as arguments are also called higher-order functions. In the example below, a function greet is created which takes a function as an argument.
Functions in the functional programming paradigm can be passed to other functions as parameters. These functions are called callbacks. Callback functions can be passed as arguments by directly passing the function's name and not involving them.
We cannot pass the function as an argument to another function. But we can pass the reference of a function as a parameter by using a function pointer.
Yes it is, just use the name of the method, as you have written. Methods and functions are objects in Python, just like anything else, and you can pass them around the way you do variables. In fact, you can think about a method (or function) as a variable whose value is the actual callable code object.
I'm not sure this is the best, but:
function A{ Param([scriptblock]$FunctionToCall) Write-Host "I'm calling $($FunctionToCall.Invoke(4))" } function B($x){ Write-Output "Function B with $x" } Function C{ Param($x) Write-Output "Function C with $x" } PS C:\WINDOWS\system32> A -FunctionToCall $function:B I'm calling Function B with 4 PS C:\WINDOWS\system32> A -FunctionToCall $function:C I'm calling Function C with 4 PS C:\WINDOWS\system32> A -FunctionToCall { Param($x) "Got $x" } I'm calling Got x Have you thought about passing a ScriptBlock as a parameter?
$scriptBlock = { Write-Host "This is a script block" } Function f([ScriptBlock]$s) { Write-Host "Invoking ScriptBlock: " $s.Invoke() } PS C:\> f $scriptBlock Invoking ScriptBlock: This is a script block If you love us? You can donate to us via Paypal or buy me a coffee so we can maintain and grow! Thank you!
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