Enable custom completers for complex user aliases

[baflo]

Creating custom completers for complex aliases

posh-git will search the $env:PSModulePath for modules whose name match posh-git-extras-* and use any
function in the found modules that has the name GitTabCustomExpansion and expects a single parameter of type
[string].

These functions receive the command as written on the console, stripped by the git binary command
and should return/write custom suggestions.

Here's how you can do it:

# Configure an alias:
> git config --global alias.wttr '!f() { curl https://wttr.in/$1; }; f'

# Find your PS-Module-Paths:
> $env:PSModulePath
C:\Users\me\Documents\WindowsPowerShell\Modules;C:\Program Files\WindowsPowerShell\Modules;C:\Windows\system32\WindowsPowerShell\v1.0\Modules

You probably want to select a folder in your user space. In the Modules folder, create another folder,
e.g. posh-git-extras-aliases and in that folder a file named posh-git-extras-aliases.psm1.

In this module file, you must declare and export the function GitTabCustomExpansion:

# C:\Users\me\Documents\WindowsPowerShell\Modules\posh-git-extras-aliases\posh-git-extras-aliases.psm1

function GitTabCustomExpansion()
{
    param(
        [string]$gitCommandBlock
    )

    switch -regex ($gitCommandBlock) {
        "^wttr\s+(?<loc>[\S]*)$" {
            @('London', 'Berlin', 'Amsterdam') |
            Where-Object { $_ -like "$($Matches['loc'])*" }
        }
    }
}

Export-ModuleMember -Function GitTabCustomExpansion

[baflo]

nvm, found out you can easily register a second ArgumentCompleter which makes this obsolete.