add a prePrompt_functions variable

Description of the new feature/enhancement

it would be the same as zsh’s precmd_functions, which is a list of functions that are called before every prompt, this would allow module makers to add functions to the prompt without overwriting it.

Proof of concept

this allows any script to register a function to run before every command by simply doing $prePrompt_functions += "<function_name>"

$prePrompt_functions = @()
$prevprompt = $Function:prompt
function prompt {
	$prePrompt_functions | Invoke-Expression
	return $prevprompt.invoke()
}

[Jaykul]

PowerLine was just a proof of concept, see Why PowerLine.

The goal was always to convince the PowerShell team to change the default prompt function to

function prompt {
    -join $prompt.Invoke()
}

… and put the current prompt into that new global as three statements:

[System.Collections.Generic.List[ScriptBlock]]$Prompt = @(
    { "PS " }
    { $executionContext.SessionState.Path.CurrentLocation }
    { '>' * ($nestedPromptLevel + 1) }
)

[vexx32]

IIRC @jaykul’s PowerLine module has some functionality like this?