Rust Programming Language Rust Linz, 28 Aug 2023

Previous Meeting Next Meeting

⏯

youtube image

►

From YouTube: Anyhow ? Turbofish - Elliot Frisch - Rust Linz January 2023

Description

Rust is a very powerful and full-featured systems language. However, its native idioms (at least in their default implementations) can be quite verbose. Even when you just want to GET a JSON document and do something with it. Explicitly matching every Result case is required to avoid panic. Or is it? Let's learn together to use turbofish syntax and the anyhow crate to produce more elegant but still idiomatic Rust code that allows us to explicitly handle Result(s) as necessary. We'll demonstrate making Rest API calls using Rust reqwest and we'll show how to incrementally minimize the amount of boilerplate it takes.

--

Elliott Frisch is a Senior Developer at JFrog with over 20 years of software design and development experience in a variety of languages. He has been working in Rust for the past year at JFrog on Pyrsia, an open source decentralized package network. His personal mantra for contributions to software is: producing exceptional products that delight users and stakeholders alike. He enjoys helping other developers with tough challenges and he is currently ranked in the top 500 users of all time on Stackoverflow. His other hobbies include a lifetime of reading and watching science fiction.

A

uh Thank you again Rainier um and thanks again for having me uh so just to start or before I really get started. um I did want to invite everyone to enter for a chance to win an apple home, pod mini uh my employer. Jay frog is a platinum member of the rust foundation and would really like to give you a chance to enter and win uh the the homepod mini. um You.

B

A

With uh the QR code, or this uh jfrock.co Link at the bottom and I believe Vernier is going to put a banner uh on the video as well.

A

um A winner will be selected within three business days and will be contacted uh via email, um so uh I I wish everyone the best of luck with uh the Apple homepod mini those are those are nice.

A

um So about me uh my name is Elliot Frisch uh at jfrog. Our core competency is helping developers. Leap Forward I've been a developer for over 20 years and writing rust code for a little over a year. Now, um I have some links here to uh various information about me, as well as the code given in this talk, uh which can be found at the the link at the bottom there to my GitHub.

A

um So I'll start with the development environment um I've been using vs code with the russ language server and a number of plugins. uh This is fully documented in the readme at the the GitHub, um but uh we can go over it. Real quick, there's, some Russ language, server, uh tab, nine uh fonts and turning on ligatures and things of that nature for a pleasant environment and under my terminal I use.

A

Oh my Z shell and then, of course, I I walk through how um I've set everything up within this uh talk, including uh you know, setting up a web server, various crates that I'm demoing um so to very very start. uh We're going to start with a very, very simple Json. In fact, the simplest Json I could, even think of which is a very simple uh version string uh with a numerical value in it.

A

um So we're gonna we're gonna parse, this version string, um so we've got, we've got a version. We've got some numerical value in it and um we're gonna use the Json, parse crate and, of course we need to match, because that could return an error uh on the handle or it could be an okay.

A

And if it's an okay, then we'll actually get a Json value, um and uh we can then display whether we we got that value or not and I'm, going to actually uh switch from here, all right, so here's the exact same code, but now in uh vs code, so that we can just run it.

A

If we execute this code, you'll see that it parses out whatever version you put in here and it doesn't matter if it's a string or not, because um we are using uh a parse function and a Json value, and so that's an enum type that can represent multiple things um and we are actually parsing it uh as a F32. So as long as it's an F32 we'll get that back out um and if it's not and of course we will get an error um that it could not parse the empty string.

A

So that is how that code functions, and we can then move on to a more sophisticated version um and actually introduce anyhow where, instead of let's go back to this first version, so in this first version, where we're parsing it there's quite a bit of of logic that has to go into the to the matching conditions to determine whether it was a string whether it was a number whether it was a short because again, this Json value is an enumerated type and when I was first starting out, this explicit matching seemed like it was excessively verbose and um so I spent a lot of time working on how I could reduce that, and the answer turned out to be anyhow, where we can, instead of matching on all of the error conditions, simply use anyhow to wrap them, and this will, instead of requiring us to match all of the various possible Json values, we can simply say attempt to parse it as a floating, a float 32, and if that fails, then wrap the whole thing in the anyhow error and otherwise uh return an okay.

A

um So this significantly simplifies uh actually parsing our Json. So if we go into the V2.

B

A

We change this to the value and run it um of course successfully parses it, and if we move the version and run it again, we'll get the same, can't parse an empty string um so so far, so good uh anyhow allowed us to eliminate a whole lot of boilerplate from version one.

A

um So that was excellent. So now what can we do? Well, what if we actually went and got some Json using a uh request blocking call, so this is going to use the HTTP request. Library it's going to make a get to a URL. It's going to get back the text of that and then it's going to attempt to parse it um and the URL. It happens to be this. uh This string.

B

A

So what I'm going to do.

A

But I can just start up a web server and I have a version Json in there and now.

A

Instead of uh parsing a simple static string, we're going to actually get that Json and parse it directly.

A

Being a little slow, sorry.

A

There we go so we got a value of 3.15 yeah.

B

Can you let me quickly interrupt you I'm, very sorry, we have a question from the audience. If you could increase the font size still a little bit if that would be possible. That would be very nice ah very good. Thank you very much.

A

And let me just move this back over I hope, that's clearer for everyone and just to remind everyone. This code is fully available in GitHub. It's also uh on those the slides that have already been shared out. So um yeah I apologize. If you, if you still can't read it um I'll, do my best to to to expand on it.

A

um So uh if we, if we now go back over to uh edit, that Json and the um V3 uh Json folder, so we'll just bump the version here to something like 8.15, why not um and now run it again, we'll see we get 8.15., so it is real code. It's actually making the the HTTP request, it's getting back uh Json and it's parsing it so so far so good! Well, what else could we do? Well what if we made a call to an actual API out there?

A

This is something called zippopotamus and um it will return kind of like we were looking at before, where we get a floating point value as a string and then have to parse it. This actually returns floating Point values and strings, and we have to parse them. So uh you know we'll we'll start with a default zip code, we'll make the request uh we'll get a Json response back we'll match on that. If it was good, we'll try and parse it.

A

So let's look at what that parse would do we'll look for places we'll get some uh geolocations out of it. We could actually use this geo utils location create if we wanted to, but I don't see the need instead I'm just going to build a Google map string based on the latitude and longitude based off of the ZIP code that we retrieve so that we can then uh see it on a Google map.

A

So that's a simple, simple use case, um and uh so we can go into the V4 folder and run it and I will give it uh the zip code of where I actually live, which is like I, said Atlanta, uh suburb technically, but Atlanta and we'll let it run.

A

Make that big, so you guys can see it again.

A

And sure enough, we get back a latitude and longitude and a Google link and if we open it.

A

There's uh Atlanta Georgia well, technically Norcross Georgia there it is um and if we simply run the same thing like I said it has a default. So if we run it with the default.

A

B

A

Very unusual location for a US, zip code. This is the Federated micronesian island of Yap, which is in the middle of the Pacific Ocean. But it's got lovely beaches and look at those it's very nice. um So we can move on uh to the last version that I've implemented here and.

A

B

A

Several different URLs and we could make all of these calls in parallel and uh iterate through them on success. So that's that's kind of what this this code's doing. It's just kind of a a reach, but it's making three different API calls in parallel and getting the results back and dumping them.

A

um So that was just kind of a.

A

What else could it do, um and obviously, if we were to execute this.

A

um You'll see that it just prints the URLs, the statuses and the text results pretty quickly. um I uh will now go back to uh presenting the actual slides, so we can go through these.

A

um So again, uh now I'm going to Pro really stop and ask if there are any questions.