Rust Programming Language FOSDEM Rust Devroom 2018, 6 Feb 2018

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From YouTube: Guillaume Gomez - Introducing gtk-rs

Description

Making the unsafe safe

The goal of this talk is to provide an introduction to the gtk bindings in Rust through the gtk-rs organization. It'll be mainly about how we made it and how we keep making it better.

Rust devroom @ FOSDEM 2018
https://fosdem.org/2018/schedule/event/rust_gtk_rs/

These talks have been recorded at FOSDEM (https://fosdem.org/)
This work is licensed under the Creative Commons Attribution 2.0 Belgium Licence.
To view a copy of this licence, visit http://creativecommons.org/licenses/by/2.0/be/deed.en

A

We are ready to start. Our next speaker is young.

B

So hi I'm here to present you a GT k RS. It won't be a technical speak at all. So if you have technical questions, we can speak after the talk. So duty cares how to make unsafely. So first, what is duty k? So it's a good Nam UI, your library, where we were used in the UNIX environments so cross-platform it works as well on the Mac and as far as I know, it works as we're on Windows, fine.

B

So a bit of history at first it was started by a very merry, are Letang in 2015 it was when we were both office in still at school. We started it to learn a rest. So first it was called gtk and we have a sub crates for each glom library like a Jo, jellyband stuff. It was all in the same repository at the opposite of currently so the first implementation was very simple. It was a one to one binding, so you had a function and object.

B

It was the same interest, so not much of entities, but you could use the gtk interest. So now the comes so yeah. It was at the time very slow to compile. We were still in 2015. It wasn't that we had a huge macro to generate. Our signals, wasn't very, very efficient, so so, since it was bound by him a lot of typos human errors were there casting errors.

B

Yeah just like I said it was just a wrapper around the C code, just one to one, not much safety and at the time the compiler was getting updated and having breaking changes like every two or three days or so changing the child. Thousands of lines at once was quite long for a library as this big, so that's I think it was at the start of 2016. We had a new contributor. We brought the gear support.

B

Some gear is a format which is used by the genome libraries to describe the API and is used by other languages to generate as our binding and that's what we did: investor with a whole new create gear which generates all the code. So that's the first thing we did. We also reworked all the GD p-- how to explain. The g lib is the base and we had to rewrite it in order to make it work to build upon it. That's it thought, and so we did, that we have.

B

We could bring a whole new rating system. So now you can say if a tray, if an object, inherits from another very helpful, it was a prevents a from a casting from a type to another. So zit and another thing which I think it's still a bit of a debate, but we decided to split libraries into is their own repository. So now Jacob isn't in GT Kelley repository anymore. It's the same organization, but not the same repository, which has its issues for every read, that's a bit, so the neutral system is basically based on this.

B

One is earth so now, when you have a function, for example, for the widget you take is a widget. So every object which implements this trait can use the videos the in this function.

B

So now, why is it better to use gtk RS / g TK directly for a few things so like it's wrote on? Let's start with compiler errors, type conversions, so in c you can totally do that. It's not a program will not much checks in Resta. You will do it with by using the Abkhaz metal.

B

It's a big difference being your work at this point. There isn't much it suggested in rester. We have her. Checks have done at compile time so here, if you try to make an invalid cast, it will just set fault when you run it. So it's inconvenient to discover there is an error in your code after being compiled when distributed and in rest. If you trace the same just in the type which isn't the children of a window, for example, a button is the children of a widget, but there isn't a bit children of a window.

B

If you try it, you won't compile. You will get an error, so so trait isn't implemented. Therefore, gtk button, it's quite convenient, so yeah. Another advantage, of course, is a cut. The readability, so I didn't see very verbose in rest, a bit less. It's the advantage of object-oriented languages not to sell you in here.

B

So summers are games, so they are quite a lot brought by rested, jackie automatic, responding and memory management brought by the rest, compiler or directly the same consentrate bonds, which are used for signals, for example, so, like that you're, surely object, won't be destroyed and curl the while being the after, been destroyed, make sense and we enforce attack when we generate the zi api that if you want a string or path which is very convenient when you have to to open a file to specify the title to be sure, you won't try to do something strange at best so, like I said above everything related to crucial, so signore's core bags, everything so yeah.

B

Some buds are gangs. Of course now you can't have arrays which have invalid size. You can't forgive. We don't allow to give a size of an array when you give it a to a function. It's a done. An array is a 5 pointer, so you have it's a Lancer provided by the type a directly, so no need give the size anymore. Very convenient and 402 have a lot less error and, of course, is a strong type system, which is one of the biggest advantage of Resta.

B

So you can't make a cast whether, however, you want just watch the function in it now at this point to what remains to be done. Well, I think we are around 90% of bindings automatically are generated and the most of missing functionality is functions. Objects are clearly in jio, so I'm starting to write new things in it directly, we'll see how much time it takes, hopefully a few months. No, yet we started recently at the last egg nominal rest, a quest to improve the a synchronous report, which is a very aster by a few people.

B

So it's coming and of course, from now the documentation is generated at the same time as the API. So we directly have a C documentation, not restaurant. So examples are it see a few, a lot of things unperfect.

B

We have still a lot of work to do in either, so it will be the next step, I think and we are done with the beginning, so beyond the dirs. So we had a few people from the genome community very interesting interest. We started a few a quest last year about this to write a Signum class project. For example, we have the previous talker is from a genome and yeah Heidi.

B

There is a Federico, a big guy in agronomy, which is rewriting a library, liber SVG invested directly. You.

A

B

That's because of him we started the thing it was for this and, of course, yeah. We have a log number libraries which start to have a binding, so just Rimmer from I, don't know where he is but yeah.

B

We have a web key to gtk and the search view and a lot more. So as long as it has a gear file. Basically, you can generate it by automatically I, don't know how it goes for GStreamer I think it's mostly Road by hand. So now we have achieve a good level. I think at this point, I would not miss much.

B

We are on little details now having a duplication having you more drugs, have been you better, interphase, better early world and at this point, how we could we do to make it even better and Ranma has been a created for that. It's a another abstraction another. So I will let its creator speak for it. So I.

A

B

C

So, as Jung said, realm is an obstruction over GTRs which provides a more idiomatic way to create desktop application in rust, and it is based on GTRs, and it also provides some support for asynchronous programming.

C

So first I'll cover some pain points I had when working with gdj RS by developing a web browser. So the first problem I had is when you want to associate some data with a widget. Let's say you the model of your application when you want to do that with GTRs because of the safety we had in rust, we need to use an RC ref saw, so we have a ref content value that we want to check the be able to borrow a check, the burrow at runtime.

C

So we need to use this boilerplate code with virome attenborough, when we want to update the model in a signal which is something we want to do somewhat frequently in geo applications. So that's never gonna make its a row prone because we only get the error at runtime instead of at compile time.

C

So one thing I wanted to tell you that if you can avoid using ref, though it's a good, it's a good thing to avoid, and what I do and well is that I use a ref cell, but I'm just not telling you so also. You can do asynchronous programming with jellyband stuff, but it's not very ergonomic and I wanted to integrate realm with the a synchronous, I/o library universe, which is Tokyo and also since Russ does not provide inheritance.

C

You cannot do, for instance, like invalidate our new class deriving from an existing widget to be able to use this new widget like any other widgets, so that's not possible in rust, so I wanted to which realm be able to destroy new widgets. That could be used the same way as the gtk widgets.

C

So realm is inspired by a language that is called M that is used for developing client-side application. So Elm is an alternative to JavaScript I found out. It provides a good way to you, a Duhamel view controller. So that's my inspiration for realm, so in annual dictionary model, which is the data that you associate with a view and you have an update function, that would take the model in response to some event and return the new model, and you also have a view function that describes your view in a declarative way in realm.

C

I use that but I adapted it to Russ. So, for instance, update- and you are not married of a widget right and we use mutation when it's convenient. For instance, the update method will take self a reference that we can mutate the model instead of having to return a new model.

C

So let's see how we can use run first, we need to declare a model which is a normal type in a row, so it could be a struct and then we use this widget attribute an info of widget, which is the trait we want to implement and for a window in this case which will create a window. So we need first, the model meadow which declared the initial model of your widget, and then we have messages that are used to communicate, for instance, between widgets or having a message.

C

Hanwen, there's an gtk event and you can also be used when there's a synchronous I/o. So, for instance, you do a network request and when it's done, you receive a message, so we use the derive while the custom derived message and we have an enum which has many variants that can have a value and then we have the view. So it's still in the Ambala yet and we use the view macro, and we now have the this declarative syntax. So we can create gtk, widgets and nest them and also set their properties.

C

We can connect the clicker and, for instance, which will send the increment message in this case, and we can also do bindings, meaning that a last line we have the text property the of the label. It is bound to an attribute of the model. So that means that whenever this attribute of the model is change, that will update the view.

C

And then we have this update method, so it takes self by mutable reference which has access to the model that we can modify when we receive a message. So in this case, when we receive the decrement message, we just change a counter attribute of the model and that will actually update the view, even though it's not shown here.

C

So how does all of that work?

C

So the widget attribute will start by collecting the data binding, so it will analyze the view check that in this case the label has a property that is called text that is bound to the contrary, root of the model, and then it will actually change the code. You write, you wrote in the Med update metal to actually update the view, so it will see here that the counter attribute was changed and it will use this value to update the view, because it noticed that there was a bending in the view.

C

So even though I use attributes ran, can work on stable rows because I used a hack to have the procedure on macro to work and the future of run will may be without futures. Also, I will work to improve the error messages because at the time I first started run. It was using the old sink right, so we didn't have access to the position of the tag, and so that's why, when you have an error message, it's shown on the widget attribute, which is not convenient and I, will support more agility features.

C

So do you have any questions? Yes,.

A

B

So the question is: take this one? So the question is: how does rested checks? The lens of arrays at compute signed its slice. It's basically, an array in rest is a slice. So in the type you have the pointer where it starts, and you have its length in the same point: it's what we call at pointers, five pointer. So when you give it to a function, we when we generate a ricotta, we we we just know the size of the slice.

B

You can't treat you when you create a slice, you know its size, you can't it's constant. So when you pass it to a function, obviously you know see its size and we can give it to the do decay function. Is it other question? Yes,.

B

So the question is: do I Anton the NGO instead to use the Tokyo for I? Think that's it.

A

B

Yeah futures so I, don't really know, for instance, with Anthony with Stark a lot about how to do a synchronous, stuff and I think he will be the best one. So this one actually, yes,.

C

In the heck fest we had I implemented the code generator the stuff to generate the a synchronous method and for now it's just working with callback. So for now, there's no support for features that, but that may be added in the future. No pun intended.

A

B

The question the question is for Jared generator. For now he asked if we intended to make it a simpler, because yeah I didn't talk about that. So I will go into details a bit. The gear generator first generate low level API, which isn't supposed to be used directly by the users and then from this.

B

It's just right to the function, the from and all the times the types from the library and from this you can how to say, we have a new serve level which is used directly and it provides the API which causes the functions are bound by the role of it.

B

So at this point yeah it's a bit complicated. If you don't know how gear works. Well, even if you know it's a bit, so we in turn the in the few more weeks to make something better. But it's more like when we have a new someone new starting a new library using the idea we take. What it says is missing.

B

So that's why we wrote this huge readme file and then we add the new elements and maybe or someday I will write a guide or something in order to avoid to just a lot more people to have their own libraries. If they want.

B