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I am very new to GNOME extension development, and I am having a hard time working with it, due to a profound lack of documentation (or maybe my Internet is clandestinely censored) of the API. I started by modifying an existing extension, so that it is easier to make my way around it.
The issue is, I can obtain the active window using global.display.focus_window, and also a list of monitors connected to the computer using Main.layoutManager.monitors. Now, what I would like to do, is find out which monitor the obtained window is sitting on (so I can move the top panel to that monitor, as it probably means I am working on that monitor at the moment). I tried various things, like .screen, .monitor etc., but with no success. I have no IntelliSense completion on this, and I am trying to guess what the members could be, as I cannot seem to find any docs on it.
I appreciate the fact that GNOME is way more customizable than what I used before (Unity, which provided no customization at all), but I don't know how to work with it and resources are scarce. I tried looking into the source code, but I am not familiar with how it is organized and I could not find the relevant portion of code where the members I need, if they exist, are declared.
I am coding the .js files, so I need some JavaScript code, I guess.
Thank you very much.
While most of the user-visible parts of Gnome Shell are written in JavaScript, these are often just bindings for the underlying C libraries. If you're working with Windows, Monitors and Screens then you're going to want to reference the Mutter documentation and probably the Shell documentation as well:
Mutter: https://gjs-docs.gnome.org/#q=meta
Shell: https://gjs-docs.gnome.org/shell01/
St (Shell Toolkit): https://gjs-docs.gnome.org/st10/
There is a property on the global object called screen (so global.screen) which is no doubt a MetaScreen which has a function get_n_monitors(), as well as get_primary_monitor(), get_current_monitor() and others. MetaWindow, on the other hand, contains a function called get_monitor() which returns an integer. I gather that monitors are referred to by integer number, which is passed to various functions of MetaScreen and MetaWindow, since there doesn't seem to be an object for that in the Mutter documentation.
Most of the related JavaScript for what you want to do seems to be in layout.js, which probably has better examples of how Mutter is used in Gnome Shell than I can give you. It also includes a Monitor class, which seems to just be a JS wrapper around the monitor index. This class is used in the LayoutManager class (which is the definition of the instance Main.layoutManager).
A note about documentation
Originally, the rationale for not having "proper" gnome-shell documentation was that the (internal JavaScript) API was pretty unstable. The deal was, you don't get a stable API but you get to read the source in the same language you're going to write it in. In some ways this makes sense, given that you can modify the prototype of live objects and monkey-patch at whim.
The API has settled down a lot, but no one has really stepped up to write a script to auto-document it, yet. My best advice would be to bookmark the Mutter, Shell and St documentation and use Github or GitLab's search to make things easier.
There is however documentation for the Gnome API as well some of the built-in modules that are worth a skim:
Gnome API: https://gjs-docs.gnome.org/
Modules: https://gitlab.gnome.org/GNOME/gjs/blob/master/doc/Modules.md
General GObject usage in GJS: https://gitlab.gnome.org/GNOME/gjs/blob/master/doc/Mapping.md
I want to make a live prototype to demonstrate transactions between two users in different browsers. It should keep the state of the UI in sync between two sessions when each user performs an action. For instance: when one user presses purchase in one browser window, the other user should see that the item is marked as sold in another.
There's nothing new about this, except that I need the absolute minimum solution to fake this behaviour in order to be able to iterate quickly to optimize the flow before starting the actual implementation.
I was thinking Flux and React, or maybe node, but I'm completely new to these frameworks.
Does anyone here have a good suggestion to the best way of approaching this without ending up building a full application? Or maybe to direct me to good starting points?
My suggestion is a NodeJS-ExpressJS-SocketIO combination solution.
It might sound scary if you don't have experience with any of those, but SocketIO is one of the libraries I usually describe as magic.
Just look at the example of the SocketIO website (which already includes everything to run) example instructions and the code of the example
I never used react so I can't say anything on how simple it is to do using it. but the big magic here is actually SocketIO. it might be usable inside react.
For the past six months or so I've been teaching myself Javascript by building a single page application that uses Raphael to create all of the elements the user sees and interacts with (see the landing page for the project for a small-scale example of what the tool will do). As I've been learning more about the language I've been coming across a lot of talk about using something like Backbone to structure the code such that it will be easier to read and maintain. While I'm not in love with the idea of taking what I've written and shoehorning it into an MVP paradigm (which would also require me to learn the paradigm), I am in favor of writing quality code that won't cause me headaches later. However, in the course of doing some google research, I've discovered that backbone doesn't seem to play nicely with SVG elements. True, there are some workarounds posted, but it seems to me that if I have to implement a kludgey work-around in order to get everything to work, the value of implementing Backbone in this case is lost as my code is still wonky, albeit in a different way. (ego compels me to point out that as it stands, the code is reasonably un-spagettified)
Given that I'm relatively new to Javascript, and to serious web programming in general, I'm posting this question here in the hopes of soliciting advice from persons more learned than I in matters such as these. If you were in my position, would you implement Backbone (or some equivalent) or would you proceed without it?
I would suggest you keep doing what you are doing. The website looks good and responsive. Do not change anything as long as you think the code is easily maintainable and readable. When you see heavy loading and spaghetti code, then you might consider about using some JS structure.
I have been a user of jQuery (and some of its minor plugins) for a while. The Javascript code I've developed over the years could be described best as... messy. It used a ton of global variables and functions here and there, didn't use standard ways of organizing the code, nor any design patterns whatsoever.
I am currently building the new version of a website, and I have completed doing the backend with PEAR::MDB2 and Smarty templates. The rest is just homebrew PHP with some classes.
Now I am at the point where I'll add the Javascript layer on top of the website to improve the user-friendliness of some features. (while making sure everything degrades gracefully) I want to write better, cleaner, more organized Javascript than I used to, so I did a little research. I read Stefanov's Object-Oriented Javascript to have a better grasp on some concepts I knew only loosely about (prototypes, constructors, etc.) as well. Now I'm stuck at a point where I wonder which Javascript frameworks I should use, and how to organize it all.
After conducting my research, I understood Cappuccino & Objective-J, and Sproutcore were not what I was looking for. To quote Cappucino's about page:
Cappuccino is not designed for building web sites, or making existing sites more "dynamic". We think these goals are too far removed from those of application development to be served well by a single framework. Projects like Prototype and jQuery are excellent at those tasks
So there's that. Then I found out about Coffee Script, which is more of a one-to-one "compiler" and wouldn't help me with the actual organization of my code.
I also stumbled on some articles that give guidelines:
Using Inheritance Patterns to Organize Large jQuery Applications
A JavaScript Module Pattern
I also found out about Backbone.js, Shoestring, JavaScriptMVC, Google Loader, jQuery Tools, jQuery UI. I don't really know what to do of all this... The things I know:
I don't want to invest too much time in learning something too complex, I want to keep things simple and flexible as much as possible (that is why I don't use Symfony on the backend, for example), yet clean and organized.
I want to use jQuery, the question is, what should I use with it? (that is compatible too)
Right now, I'd use jQuery and jQuery Tools and "organize" all that in a simple namespace/object literal with simple properties and methods and also, since the site is localized, I just plan on using the simple vsprintf (as I do on the backend) with key:value pairs loaded from an object literal provided by the backend. JavaScriptMVC seems interesting, but I fear it would bring way too much complexity for a project that is fairly small sized. That is where I need your advice! Thank you very much in advance.
Ok, my attempt at an answer:
There is no 'best' to way to do it. You now know what's there and I think you might have a preference for yourself for what you want. In that case, pick a framework and learn it inside-out. (sorry to burst your bubble, but each framework has a learning curve, some steep, some very easy, but in the end to use it well you have to invest in it. Just do it, you won't be sorry).
You of course have an preference for clean code, so you might take some considerations into account. You also say you have a preference for jQuery, which is fine, but there are some limitations (as also pointed out in the link provided by eskimoblood).
There are some nice lectures / and tutorials with advice on how to structure your code in jQuery:
How to manage large jquery apps
On Large jQuery apps
Essential Javascript and jQuery patterns (free ebook)
Some style guides:
Jquery core UI Styleguide
Google Closure Javascript Style Guide
Tools for checking your code
JSLint
JSHint (a more forgiving/practical fork)
Closure Linter (haven't tried it yet, but intend to)
Standard works (javascript)
Everything by Douglas Crockford
Quirksmode
There might be more.. perhaps more people can contribute, but I also think that you've almost reached the end of what you can learn before getting your hands dirty. Many of these guides are written in a very generic way, but the interesting thing is that javascript is called upon in many specific situations. It might be useful to just post some of the code that you regard as "messy" and we can help you figure out how to do it better. Good luck!
You should watch the video and read the links in this article and then you should ask yourself again if jquery is the right tool. Maybe you will use dojo, that is much better for larger projects or you take a look at backbone and where you can stay with jquery. After all both of them are more "javascriptish" then something like sproutcore, cappuciono or even GWT. And also much easier to understand when you come from jquery.
One framework that is to consider is definitely ReactJS from Facebook. This framework is pretty slick in many ways.
First thing you have to know is that it is a view framework. It can be used server-side to do the pre-rendering of pages, but it really shines on client side. Since it's a view framework, it can be used with backbone or any other "back-front"-end framework.
One of the main point of React is its rapidity. It keeps a virtual DOM in memory and virtualize all the webpages events. So the virtuals event are used to keep events browser agnostics.
The virtual DOM kind of make programming a dynamic site as if you were programming an old static website. You can just shoot the whole HTML to render to the view engine (as if you were "re-rendering" the whole page) and it will manage the DOM operations. It does a diff between the new virtual DOM and the current virtual DOM and only inserts nodes that needs to be inserted. This way you reduce the number of DOM ops and thus increase your render speed by a lot.
A good place to start is this tutorial which shows how to use "Flux" (the web flow designed by Facebook for its site) in order to realize a Todo application!
Coming from Java, I'm wondering if a Java best practice applies to JavaScript.
In Java, there's a separation of interface and implementation, and mixing them up is considered a bad practice. By the same token, it is recommended to hide implementation details of your library from end developers.
For example, log4J is one of the most popular logging libraries out there but it is recommended to write code to the slf4j library or the Commons Logging library that "wraps" log4j. This way, if you choose to switch to another logging framework such as logback, you can do so without changing your code. Another reason is that you, as a user of a logging library, how logging is done is none of your concern, as long as you know what logging does.
So back to JavaScript, most non-trivial web applications have their own custom JavaScript libraries, many of which use open source libraries such as jQuery and dojo. If a custom library depends on, say jQuery, not as an extension, but as implementation, do you see the need to add another layer that wraps jQuery and makes it transparent to the rest of JavaScript code?
For example, if you have the foo library that contains all your custom, front-end logic, you'd introduce the bar library that just wraps jQuery. This way, your foo library would use the bar library for jQuery functions, but it is totally oblivious to jQuery. In theory, you could switch to other libraries such as dojo and google web toolkit without having a big impact on the foo library.
Do you see any practical value in this? Overkill?
Although it makes sense from a theoretical standpoint, in practice I'd say it's overkill. If nothing else for these two reasons:
Anything that adds to the size of
the request (or adds more requests)
is bad - in web world, less is more.
If you're using say jQuery, the
chances of you switching to
something like Mootools is (imho) slim to none. From what I've seen, the top libraries each aim to solve different problems (at least in the case of Mootools and jQuery - see this great doc for more info on that). I'd assume that you'd incur a tremendous amount of headache if you were to try to implement a middleware library that could easily switch between the two.
In my experience and being a Java developer myself, sometimes we tend to take the whole "abstraction" layer pattern too far, I've seen implementations where someone decided to completely abstract a certain framework just for the sake of "flexibility" but it ends up making things more complicated and creating more code to maintain.
Bottom line is you should look at it on a case by case basis, for example you wouldn't try to create an abstraction layer on top of struts, or on top of JPA, just in case you then go to a different framework (which I've rarely seen done).
My suggestion is, regardless of the framework you are using, create objects and components that use the framework internally, they should model your problem and be able to interact between them without the need of any specific framework.
Hope this helps.
There are a lot of good answers here, but one thing I don't see mentioned is feature sets. If you try to write a library to wrap the functionality provided by, say, jQuery, but you want to be able to easily swap out for something like prototype, you have a problem. The jQuery library doesn't provide all the features prototype provides, and prototype doesn't provide all the features jQuery provides. On top of that, they both provide their features in radically different ways (prototype extends base objects -- that's damn near impossible to wrap).
In the end, if you tried to wrap these libraries in some code that adds 'abstraction' to try to make them more flexible, you're going to lose 80% of what the frameworks provided. You'll lose the fancy interfaces they provide (jQuery provides an awesome $('selector') function, prototype extends base objects), and you'll also have to decide if you want to leave out features. If a given feature is not provided by both frameworks, you have to either ditch it or reimplement it for the other framework. This is a big can of worms.
The whole problem stems from the fact that Java is a very inflexible language. A library provides functionality, and that's it. In JavaScript, the language itself is insanely flexible, and lets you do lots of crazy things (like writing a library, and assigning it to the $ variable). The ability to do crazy things lets developers of javascript libraries provide some really creative functionality, but it means you can't just find commonalities in libraries and write an abstraction. I think writing javascript well requires a significant change in perspective for a Java developer.
Someone wise once said "premature optimization is the root of all evil." I believe that applies in this case.
As others have expressed, you don't want to abstract for the sake of flexibility until you have an actual need for the abstraction. Otherwise you end up doing more work than necessary, and introducing unnecessary complexity before it is required. This costs money and actually makes your code more brittle.
Also, if your code is well organized and well tested, you should not be afraid of major changes. Code is always changing, and trying to anticipate and optimize for a change that may or may not come will almost always get you in more trouble than it saves you.
Acknowledgement: I should give credit to Agile programming and my practice and readings on the topic. What I've said comes directly from my understanding of Agile, and I've found it to be an extremely good razor to cut out the extra fat of my work and get lots done. Also none of what I've said is actually JavaScript specific... I'd apply those principles in any language.
There are good arguments calling this development practice - wrapping in order to switch later - into question in any language.
A good quote by Oren Eini, from his writeup on wrapping ORMs:
Trying to encapsulate to make things
easier to work with, great. Trying to
encapsulate so that you can switch
OR/Ms? Won’t work, will be costly and
painful.
This is definitely something that is done in enterprise environments.
Take for example a company that has their own custom javascript framework that is used on all of their projects. Each of the projects decide to use their own framework (jQuery, Dojo, Prototype) to add functionality to the underlying modules of the company framework. Employees that move between projects can now easily do so because their API with working the project's codebase is still the same, even though the underlying implementation could be different for each project. Abstraction is helpful in these situations.
It is overkill. Javascript is not Java and is not in any way related to Java. It is a completely different language that got J-a-v-a in the name for marketing reasons.
If you are concerned with availability of add-on libraries, then choose a framework with a large ecosystem. In an enterprise environment you will be further ahead by standardising on a vanilla off-the-shelf uncustomised web framework that you can upgrade every year or so tracking the rest of the world. And then supplement that with a SMALL in-house add-on library which you will, of course, have to maintain yourself, not to mention training any new programmers that you hire.
Since you are talking about Javascript in the client (web browser) it is more important that you limit the complexity of the things that people do with it. Don't build huge amounts of client side code, and don't make stuff that is so brittle that another programmer can't maintain it. A web framework helps you both keep the linecount down, and keep your own code reasonably simple.
It is not a question of Javascript best practice, because that would be different for server-side JS such as Rhino or node.js.
Adapter pattern is not a common solution in this case. The only example I know to use this pattern is extjs. Javascript projects are usually too small and they aren't worth the effort you would make by creating such an abstraction layer.
The common solution for this problem is that you try to use multiple frameworks together for example with jquery.noConflict.
I've done this before, and can talk a bit about the experience of writing a library/toolkit wrapper.
The plan was to move from Prototype to some other library. Dojo was the first choice, but at the time I wasn't sure whether that's the library to move everything to (and by everything I mean ~5MB of Prototype-happy JS). So coming from a world of clean interfaces, I was set to write one around Prototype and Dojo; an awesome interface that would make switching out from dojo a breeze, if that was in fact necessary.
That was a mistake that cost a lot of time and effort for a few reasons. The first one is that although two libraries can provide the same functionality, (a) their API will almost always be different, and most importantly (b) the way you program with one library will be different.
To demonstrate, let's take something as common as adding a class-name:
// Prototype
$("target").addClassName('highlighted');
// Dojo
dojo.addClass("target", "highlighted");
// jQuery
$("target").addClass("highlighted");
// MooTools
$('target').set('class', 'highlighted');
Pretty straight-forward so far. Let's complicate it a bit:
// Prototype
Element.addClassName('target', 'highlighted selected');
// Dojo
dojo.addClass("target", ["highlighted", "selected"]);
// jQuery
$("target").addClass(function() {
return 'highlighted selected';
});
// MooTools
$("target").set({
"class": "highlighted selected"
});
Now after choosing an interface for your version of the addClass you have two options: (1) code to the lowest common denominator, or (2) implement all of the non-intersecting features of the libraries.
If you go with the 1st -- you'll loose the "personality" / best qualities of each of the library. If you go with #2 -- your addClass' code will be at 4 times larger than the ones provided by any of the libraries, since for example when Dojo is included, you'll have to write the code for the function as the first param (jQuery) and the Object as the first param (MooTools).
Therefore, although it is theoretically possible, it isn't practical, but is a very nice way to understand the intricacies of the libraries out there.