Composer is a powerful dependency manager much like Bundler for 0:00 Ruby or NPM for Node.js. 0:04 All of these systems helped developers share code they have built and 0:06 implement shared code. 0:09 Composer works in a very similar way. 0:10 You can specify exact versions of the code that you would like to install. 0:13 This helps ensure that you don't accidentally get 0:17 major updates which could break your application, but still get bug fixes and 0:19 patch improvements when you run Composer update. 0:22 Composer is available from getcomposer.org. 0:25 When you click on the Getting Started link down here, 0:28 we can see installation instructions for popular operating systems. 0:30 Number five here, we have installation for 0:34 Windows, and at number four here, we have installation for *nix. 0:36 It's a bit of a, a bit of a confusing name, but it means that these 0:41 are the instructions for OS X, Linux, and any other Unix-based system. 0:44 We already have Composer installed in Workspaces, and 0:49 we can access it using the console feature. 0:51 If we go back to our workspace, we can take a look. 0:53 Now, we haven't used console before, but we can access it from View > Show Console. 0:56 You might recognize this as looking very similar to an OS X or 1:01 Linux terminal, and it is. 1:04 It works in very much the same way. 1:05 Now, from here, we can check that we have Composer installed just by 1:07 running the composer command. 1:10 If we see information like this, then it means it's installed. 1:12 Let's pretend for this lesson that we're building an application that requires 1:15 reading files from a ZIP file, and maybe in the future, 1:18 it also needs to support things like Amazon S3 or FTP drives. 1:21 That would be rather complicated to write ourselves, but luckily, 1:25 we can just install the Flysystem package from The League of Extraordinary Packages. 1:28 Now, to do that, we simply run composer require league/flysystem. 1:32 And what this will do, if there's no composer.json file already, 1:41 it will create one. 1:46 Otherwise, it will append to it. 1:46 But we don't have one, so we can assume it's going to create it. 1:48 When we run this, it will ask us which version we want. 1:51 Normally, it would be bad idea to specify any version at all, but for 1:54 now, it doesn't really matter and we can make it more specific later. 1:58 So we put star. 2:02 It just means, get me any version you can find. 2:03 [BLANK_AUDIO] 2:05 There we go. Looks like it's installed version 0.5.6. 2:09 And it's just suggesting a few other packages that we could install if we 2:14 wanted to, but we don't care about those. 2:17 So if we look with ls, we'll see we have some new files. 2:19 Let's refresh our workspace files and see what we've got. 2:23 So as I mentioned, a composer.json file has been created, and 2:27 inside we just have some basic JSOB with an array of stuff. 2:30 This array, we have require here, which is where we list all of our dependencies. 2:34 On the left, we have the names of our dependencies, and 2:39 on the right-hand side is the version. 2:41 So as I said, it's a little bit vague at the moment. 2:44 It's the version, but we know that it's installed 0.5.6. 2:46 So why don't we just say 0.5.*? 2:49 That means if updates come out, then it won't completely break our code. 2:53 Composer's also created a vendor folder with this autoload.php. 2:56 We'll look at that in a second. 2:59 Composer, which you don't need to look at. 3:01 This is some internal logic. 3:03 And it's created the league folder with our Flysystem package. 3:05 And this is where all the code for 3:08 Flysystem lives, especially in the source folder here. 3:10 So this is all the code that makes Flysystem run. 3:13 We haven't had to copy and paste anything or, or add anything. 3:17 It's just, it's just straight in there. 3:20 Finally, we can see a composer.lock file has been added. 3:22 This is similar in theory to the composer JSON file, 3:25 but it contains much more specific information. 3:29 Unfortunately, we can't preview it in Workspaces, but it contains information 3:32 like, was it installed from Git or was it downloaded from a ZIP file? 3:35 If it was downloaded, what was the exact checksum so 3:39 we can make sure that we are using the exact same version as each other. 3:41 You never want to edit the lock file, but whenever you want to compose a update, 3:45 .lock will be updated and you should commit the lock file. 3:48 So, with Composer installed and our new dependency Flysystem available to use, 3:51 let's have a look at how it all fits together. 3:55 [BLANK_AUDIO] 3:57 So, in previous versions, we made our own Bootstrap file, 4:00 which contained our own autoloader. 4:04 We don't need that anymore because we can just include the vendor autoload.php file 4:06 like we're doing on line three here. 4:11 This includes Composer's autoloader. 4:13 That means we don't have to worry about autoloading a tool. 4:15 As a side note, require is exactly the same as include, 4:17 with the added benefit of if it can't find the file, it will error. 4:20 So if you run your code and it says, line three failed, require could not 4:24 find vendor/autoload.php, then you know that you need to run composer install. 4:28 So, let's move this console down a little bit so we can look at our code better. 4:33 Okay, we've got some new stuff here. 4:38 On line seven, we have use League\Flysystem\Filesystem. 4:40 This avoids us having to reference the entire class name with all of 4:45 its namespace prefixed each time we use it. 4:47 We can now just reference Filesystem and PHP will know which class we mean. 4:51 On line eight, we have another use statement, 4:54 which lets us alias the Zip class to the global space. 4:57 This means we can reference Adapter and not Zip, which is a very common name and 5:00 might conflict with something else. 5:03 On line ten, we are instantiating an object as an instance of Filesystem, 5:05 containing an instance of Zip as a constructor. 5:10 That Zip class is then taking the location of the ZIP file as we want to read, 5:13 as a string argument, and that location is in the current directory /archive.zip. 5:17 Then, line 13 uses a Filesystem object method named listContents, and 5:24 we output everything into some HTML at the bottom. 5:29 This HTML makes an unordered list on line 24, and 5:33 proceeds to loop through on lines 25 to 27 down here. 5:36 This little for each will go through our contents, and 5:41 then make a content variable for each item it finds. 5:43 Finally, line 26 outputs a few values from the content array. 5:46 The type will say file or directory is a string. 5:50 And the path value will be the name and 5:54 location of the file inside our archive.zip. 5:56 So, let's run this and see what we get. 5:58 And there we have it. 5:59 A complex task made super easy just by installing a Composer package. 6:02