Next Generation Shell Weekly Meetings, 6 Feb 2022

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From YouTube: NGS weekly meeting #17 - 2022-02-06

Description

Project website - https://ngs-lang.org/

Release script - https://github.com/ngs-lang/ngs/blob/9f72d55f1889e2d9c6eab4d3a229858bf5653a21/release.ngs

Discord - https://discord.gg/6VqgcpM

A

Hello welcome to ngs weekly meetings. Ngs stands for next generation. Shell, I'm ilya share the author. Weekly meetings are about recent progress and future plans. Let's start okay, so ricardo is not with us today because he is busy. That's fine! It's all you know volunteer volunteer work, so no questions asked even um uh yeah.

A

So ricardo reminded me that uh well we don't have a release script yet and we should really automate the release and he is right- and I had it kind of in the back of my mind, but since chicago reminds us that's what I'm working on recently, um but let's maybe uh before we dive into that. I would like to share my screen and discuss uh very shortly the milestones.

A

Okay. So where are we um muscle 0 to 14?

A

The tasks are finished and we need to release 0 to 15.

A

I'm working on it.

A

But, but I'm also working kind of mostly switched to the release script so 0 to 14 about to be released, 0 to 15. Some work is being done.

A

We had- I don't remember if you reported the previous week or not, uh we have update to the site on the dev branch which is not released. Yet uh we are supporting dark team now on the site, not released, but it's will be released soon, okay. So what I would like to do now is to share my screen and share the release, script and discuss.

A

Not from the perspective, what uh what's to do and what's done, but more as a general explanation about how ngs scripts look and uh how they work.

A

So since we don't have much up many updates today's, so I thought maybe I'll dive a bit into um one particular example of uh ngscript. So I'll share my screen a specific window, more precisely, yeah okay. So this is a script that I'm working on.

B

A

Yeah so maybe uh let's start.

A

Top to bottom, but before that I forgot to mention that in the beginning I also mentioned what ngs is next generation. Shell is a programming language which is a modern programming language for devops, so whatever you would be writing in bash or python ruby peril.

A

There is quite a big chunk of these things as it devops things which.

A

I would like people to switch to ngs4 and I would like to switch because I I think um people will be more productive. Is this uh with the switch, uh because ngs was specifically intended for this niche, it's not about being better or worse than other languages.

A

It's about particular fit for the tasks. Okay. So with all that in mind, let's go from top to bottom of the script, so well, uh first line yeah we're on the switzerland.js, nothing particularly surprising here. uh This is my comment. uh I'm actually translating the release process document which you have in the repository at the top level. Also- and these are all the steps that I'm currently doing manually.

A

There is a review step which, which is kind of intended to be manual, but I think I can somewhat.

A

Let's say eliminate most common cases where there are no new changes on master, which is a typical use case, and so, um as I really script will detect the will, detect this and just continue running without any intervention on my part.

A

Okay. So here we have original document, and this is just a start of translating the document into a script. So ns ns is a namespace declaration in ngs the definition. Actually, um this will go away because all files will have this namespace wrapper, like you have in let's say javascript and python um right now, without an s, you would have this source branch and target branch.

A

This would become global variables, not very good, and I didn't want to expose them. So I'm using an s you, you can actually work without an s, but it's.

A

um Unintended and advised against, let's say so: you should use namespace um yeah. Okay. What do we have next, as the definition of the main function? What's important and just doesn't actually look for this function from the start? What is happening?

A

The skip runs top to bottom and when this file finished executing and just will check whether the main function was defined and invoke that if it was defined so what's the great point here is that if you just have simple top to bottom script, you don't have to define the main function and it will just work.

A

So why I'm defining main function here, because I expect to get command line arguments like version, for example, it would be a string that will be added later, but I already know that I will add that and what what is happening, if you do this, if you do this, if you give the parameter to the main function and js will see that and will automatically match the command line arguments um with this parameter. So you don't need to do like manual parsing of um of the command line arguments.

A

It will be just here available to you. So, let's go back for a moment: okay! So what's next worn work in progress? Okay, so we warned the user that it's not like production ready script.

A

So, what's interesting with worn, the output is going to standard error. I can just show this word hey and looks like this warning this timestamp. Okay, why we got null null here because n is actually elias.

A

For ngs print expand print inspect, so it actually inspects the return value. If you just want to run, that's ngse like evaluate.

B

A

So what's next next thing I don't want to.

A

uh To ruin anything in the current directory, where the script is because that's the checked out code that I'm working with so, for example, if I would delete the build folder on my my machine, uh the ngs binary is actually linked to the build folder, so it just crashes. So I don't want that. I'm copying copying the working directory into another directory, but let's discuss this for a moment. This is a temporary directory, so ngs had up until recently had tmp file.

A

So what tmp file and tmpd have in common is the behavior on exit on exit, the temporary file or temporary directory are automatically removed, and actually there are several policies about how to remove the file. So in this particular case, by the way this, um like requirement to have these policies uh comes from my friend andre. He looked at the temporary file and said, okay. What?

A

If I don't want to, if something crashed, what I want to see what happened so either policies quite a bit ago, so I'm creating temporary directory here uh and this temperature directory will be removed automatically unless there was an error, and in that case this directory will be kept.

A

I'm logging, where this directory is uh this, is not strictly necessary, because if you have this policy, oh I can. I can just show what happens.

A

Okay, let's see uh what happens if the script crashes, okay, I'm creating temporary directory, I don't need any reference to it and then I just want to crash okay. So in this case, if this policy is active and the directory is kept, you will have log which says tmp there, and I did nothing in my script in my command line to have that as a behavior which is built in so this log is not strictly necessary.

A

Even if you want to find this directory afterwards. It just all works. Fine. uh What else? Okay, four four by itself, is not anything particularly interesting. It creates iterator from this array, and we are going over this two branches, which is one is dev. Second, is master.

A

We have branch directory.

A

uh Which is a subdirectory of temperature directory? What is happening next? We are copying current directory into that branch directory. uh We clean that directory up his kit reset hard and then check out the needed branch.

A

I don't know if I actually need that I'll figure this out later, but meanwhile that's how it is what's interesting about running external programs, several things. First of all, you see log here.

A

That means that you will have this program logged before running.

A

And this is an example: yeah writing command, ls, okay, so these are things are called options. uh They must have colon if nothing follows the colon. That means that the value is set to true that's kind of implementation detail, but nevertheless uh it is useful in several ways like, for example, with log okay, cd is another option is where you want to run the command um yeah.

A

So by now you probably have noticed that all commands here are prefixed with log, and I will need to figure out in ngs how how one could possibly run several commands with the same options. It is a useful feature, I think, and right now it's not implemented in any way.

A

You could potentially redefine the dollar dollar parenthesis command and uh well it it will work. It will not look good and it's a bit cumbersome. There should be something simpler than that: okay, so what we have after the four we have source tier, which is the source branch there target deer, which is quite clear okay.

A

So there are several several things which will happen in the source there, which is the um dev branch, I'm removing build, I'm making build running tests running this, and you can once again see that there's a bunch of options which are copy paste here and uh that's not good.

A

I will look into a way to eliminate this duplication.

A

uh We can run the script and just to show how that looks. uh It doesn't do anything useful yet, but we can observe how it looks.

A

Okay, so the log of the comment also shows with which options it was run, because that was also a recent addition, because it was printing without the options, and then I okay, where it does that. Because I have several directories- and I don't know which one.

A

Types count: okay, that is, output of a script which is um run by this, make comment and what we can observe is actually indistinguishable.

A

From the from the release in javascript- and maybe we should actually do anything about that- yeah- maybe to add pid or something to this log because well.

A

It's pretty hard to understand what is going on. You know it's not like.

A

Well, if you do things like that in bars, typically, the commons would prefix the error message or the log message with their own name, so need to think about this. Maybe pid, maybe name to be uh solved.

A

Okay, so we just went over the script. uh I don't think there was anything like completely surprising.

A

I think that we have seen several power features like temp tier and something that, uh for example, if you work in bash, you would have like trap commands to trap the exit process uh delete- and you know- and all of this is just repeated with so many scripts- that I don't see any particular reason not to factor this out into standard library where tmpd is actually defined, and my kit.

A

Okay, uh so uh leave comments. If you have any uh questions or advice or recommendations uh also feel free to open github issues. If you think of something feel free to join our discord, I'm there I can help you with adoption of ngs questions other help. What not uh well hope you liked this episode, uh how to say like and subscribe.

A

Thank you see you next week.