PowerShell 5.1 What's the difference between inline function and all the other ones?

Question

I'm using PowerShell 5.1 and I'm using inline functions just fine in my script. But I can't find anything online telling me why I wouldn't use inline functions. My main context is using Azure pipeline tasks to call my PowerShell scripts.

Those appear to be names of code snippets. What does it insert if you go for the `function-inline` snippet? "Inline function" is not a concept within PowerShell itself, as far as I know ("advanced function" is), but of course people are free to name their snippets whatever they like. — Jeroen Mostert, May 19 '22 at 16:10
doh! it actually explains a little about it if you hover over it in VSCode — Rod, May 19 '22 at 16:12

score 4 · Answer 1 · answered May 19 '22 at 16:19

function-inline is a snippet for a function where the parameters are defined inline with the function name rather than in a parameter block.

The function-inline creates:

function FunctionName (OptionalParameters) {
    
}

Whereas a function is:

function FunctionName {
    param (
        OptionalParameters
    )
    
}

The different location of OptionalParameters is the only difference.

IMX, parameter blocks are typically preferred for all but the most trivial of functions.

Nicely done, but what does _IMX_ mean? – mklement0 May 19 '22 at 17:47 — mklement0, May 19 '22 at 17:47

score 3 · Answer 2 · answered May 19 '22 at 17:44

Bacon Bits helpful answer already shows the basic syntactic difference.

A major difference is that you can't use the CmdletBinding attribute with inline functions.

Somewhat surprisingly, you can write advanced functions as both inline and non-inline functions:

# Advanced function using inline syntax:
function InlineFun( [Parameter()] $a ) { 
    $PSCmdlet 
}

# Advanced function using non-inline syntax:
function Fun {
    param( [Parameter()] $a ) 
    $PSCmdlet 
}

A function becomes an advanced one if it either has CmdletBinding() or at least one Parameter() attribute. As proof the functions output the automatic $PSCmdlet variable, which is only available to advanced functions.

One case where you actually need the param() block is when you want to write a parameter-less advanced function:

function Fun {
    [CmdletBinding()] param() 
    $PSCmdlet 
}

In this case you need to use the CmdletBinding() attribute, which can't be used with an inline function because it is an attribute of the param() block.

PowerShell 5.1 What's the difference between inline function and all the other ones?

2 Answers2