Adding snippet for class based argument completion

[powercode]

Adding a snippet with a class based Argument Completer and simple usage examples.

Is has helper functions for the most common use cases I have encountered when writing completers.

I am a bit hesitating about the examples - Do they belong here? Maybe we should have one snippet without them?

[TylerLeonhardt]

I've thought about this for a bit. I'm not sure how many folks create argument completions. If not a lot of folks do it, I'm hesitant to add this to the snippets that ship with the PowerShell extension. Feel free to change my mind!

That said, perhaps what we should have is a doc in this repo that consists of a bunch of user develop snippets for misc scenarios? In that doc we could also have instructions on how to make your own snippets so that it's easier to get started with snippets.

Thoughts? (@SeeminglyScience, @rkeithhill, and @rjmholt)

[rkeithhill]

How about we make this an example? We could do more with our examples. There is a some stuff in there for dealing with paths but hey, the more examples the better IMO.

[powercode]

I have no strong feelings about it at all. I just write completers for most of the scripts/modules I write, since I believe that is one of the greatest usability boost you can get.

I have a PR for the C# version of this in the engine, so it may be better to wait for that. This is more of a stop gap, or for Windows PowerShell

[TylerLeonhardt]

@powercode do you mind if we make your snippets the first snippets to go in the "community snippets"? I've got a PR out about this:
#1246

I'll make sure to give you credit.

[rjmholt]

Now that this is part of community snippets, we should probably close this.

[rkeithhill]

I agree with @rjmholt

[rkeithhill]

@powercode Any progress on the PowerShell repo issue you submitted on simplifying tab-completion? Just spent a weekend on a tab-completer for a moderately complex native app. Kind of a PITA. I really wanted to use Native-CommandTree in TabExpansionPlusPlus but it could not handle the fact that this app has some "subcommands" that look like parameters.

[powercode]

@rkeithhill It got put on hold to "get more input". Bot closed it a week ago, but I'll be back.

I've run into exactly the same issue with nct, and the work I've done so far is really only useful for cmdlet completions.

I'm still trying to figure out a good way of doing this for native commands. I have started modeling what rust is doing with https://clap.rs/. A fluent API for describing command lines, but it is too much of a WIP to share yet.

[rjmholt]

Interesting, I remember @lzybkr also talking about Rust's CLI experience in comparison to PowerShell. I feel like clap might have been what he was referring to.

[lzybkr]

Yes, I most likely mentioned clap, which now will automatically generate completions that include tooltips for PowerShell.

Another cli framework worth looking at is knack - used for the vsts and az clis. I recall seeing another interesting framework written in go as well, maybe used for kubernetes.

[rkeithhill]

clap reminds me a bit of the Genghis command line parser that Chris Sells and friends developed for .NET back in 2002. http://sellsbrothers.com/12655