PSR-2

This is a more controversial recommendation than PSL1, 0:00 which is widely used and adopted. 0:03 PSL2 is used widely too, but 0:04 has a few parts that some developers are happier about more than others. 0:07 The reasoning here, is that PSL2 is a style guide and 0:11 each developer has their own unique preferences when it comes to style. 0:14 Regardless of the personal preferences of a developer, 0:17 using PSL2 has many benefits for your code. 0:20 And as everyone conformed to a single code style guide, which helps avoid all sorts 0:23 of obscure problems with version control and co-contribution from third parties. 0:26 Its also a great set of common rules to follow when you work on a team. 0:31 To stop any potential arguments that might pop up about where a bracket should go. 0:34 You can just do what PSL 2 does. 0:37 I'm gonna take you through the rules in the overview. 0:40 One at a time and explain what they mean. 0:42 Code must follow PSR1. 0:44 To be PSR2 compliant, you also have to follow the rules in PSR1. 0:45 PSR2 adds on top of these rules. 0:50 Code must use four spaces for indenting not tabs. 0:53 This seems counter-intuitive to many. 0:56 The tabs versus spaces wars have been going on forever and 0:58 will never end, but the important thing is consistency. 1:01 The more projects use the same thing, the less IDE config switching you need to do. 1:04 PSR2 pick spaces, so that's what we'll do. 1:08 Any good editor, can be set to enter up to four spaces when you hit 1:11 the Tab key on your keyboard, so this isn't a problem. 1:14 There must not be a hard limit on line length. 1:18 The soft limit must be 120 characters, and lines should be 80 characters or less. 1:21 This just means it would be cool if you kept your code at less than 80 characters, 1:27 but that's not always possible. 1:30 It probably shouldn't be more than 120 either but if it is, 1:32 just give a warning not an error. 1:35 There must be one blank line after the name-space declaration. 1:37 And there must be one blank line after the block of use declarations. 1:41 This just helps things look pretty, 1:45 by adding some white space around the namespace declaration. 1:46 Opening braces for classes must go on the next line, and 1:50 closing braces must go on the next line after the body. 1:53 That just means put curly brackets for classes on their own lines. 1:56 Opening braces for the methods, must go on the next line, and 2:00 closing braces, must go on the next line after the body. 2:03 Put curly brackets for methods on their own lines too. 2:06 Visibility must be declared on all properties and methods. 2:09 Abstract and final, must be declared before the visibility, and 2:12 static must be declared after the visibility. 2:16 This sounds a little confusing. 2:19 But if you're creating an abstract or a final class which is public, 2:20 the word abstract or final, should come before public. 2:23 If you're using static classes, and 2:27 that method is public, then you should write public before you write static. 2:28 You might not have learned about abstract final or static classes yet. 2:31 These are all fairly advanced features. 2:35 So if you're unsure what they are, just ignore this rule for now. 2:37 Control structure keywords must have one space after them, and method and 2:40 function calls must not. 2:44 Control structure keywords are things like if, else, switch, do, while and for each. 2:45 You need a space after these words, and before the opening bracket. 2:51 Opening braces for control structures, must go on the same line. 2:55 And closing braces, must go on the next line after the body. 2:59 This means things like if, for each and while, need to have their curly bracket on 3:02 the same line as the keyword, instead of dropping it down a line. 3:06 Opening parentheses for 3:10 control structures, must not have a space after them. 3:11 And closing parentheses for control structures, must not have a space before. 3:14 That means no white space after the opening bracket, and 3:18 no white space before the closing brace. 3:20 It can be quite hard to understand what all of this means. 3:23 To help us, we can install a tool called PHP_CodeSniffer. 3:26 This will allow you to test your code matches against the standard. 3:29 Let's hop over to workspaces to see how CodeSniffer works. 3:32 If we want to start working with PHP_CodeSniffer, 3:36 the first thing we should do is install it. 3:38 As with many things, we can use the concert on here and type, composer choir. 3:40 The name of the vendor is Squizlabs. 3:47 The name of the package, PHP_CodeSniffer. 3:50 And once again, this is a dev dependency. 3:54 We are only using this for development and not production. 3:56 It's gonna ask us to pick a version constraint. 3:59 Once again, we don't really care. 4:01 So there you can see Composer doing the work. 4:02 It's installed CodeSniffer, and now it's there. 4:04 Now, just like with PHPUnit, we can run vendor. 4:08 Bin, this is where our code lives. 4:13 And phpcs, is the executable for CodeSniffer. 4:16 Then we pass SRC as an argument, 4:20 as that is the only directory we want to sniff right now. 4:23 We can leave our tests and vendor folders alone. 4:25 Next, we have to specify the standard option. 4:28 Two hyphens. 4:33 And we want to pass PSR2 as the value to that, 4:34 because that's the name of our standard that we want to test against. 4:36 If you run this, CodeSniffer should tell us anything that it finds that's 4:40 not PSR2 complying in any of the PHP files that exist inside the source folder. 4:43 Lets have a look at what it's found. 4:49 Okay, here we go, it's found errors inside, source example.php. 4:50 Cuz it has, that's the only file that we have. 4:58 And there's quite a few errors here. 5:01 These numbers here, are line numbers. 5:03 This is the severity of the error. 5:05 Warnings you can kind of ignore. 5:07 Errors are a problem, and 5:09 it has a human readable message explaining what's actually going wrong. 5:10 Let's have a look at example.php and try and fix it. 5:14 So, there must be one blank line after the namespace declaration. 5:17 That makes sense. 5:21 It also probably shouldn't be jammed up there either, 5:22 must be one blank line after the you statement. 5:24 Zero found. 5:26 Okay. 5:27 We can put a line in. 5:28 Nice and easy. 5:29 Let's try and shrink this list of errors down a little bit. 5:31 Okay. What happening now? 5:37 Line six, that's here. 5:38 Opening brace of a class must be on the line after definition. 5:40 Oh, okay. Well the definition line is right here, 5:44 and then we have a space and a bracket. 5:47 PSR2 says that it should be underlined by itself. 5:49 Run again. 5:52 Excellent. We're starting to get rid of some of 5:54 these errors now. 5:55 Class constants must be uppercased. 5:56 Expected FOO, but found lowercase foo. 5:58 Easy fix. 6:02 Don't forget to change any references to this constant as well. 6:03 Expected function abc, but 6:07 found function abc with a space in between the first parenthesis. 6:09 So we don't have a function called abc. 6:14 This is just a template error. 6:15 What they're really trying to say is, 6:17 that on line ten which is right here, there shouldn't be a space here. 6:19 So you can get rid of that. 6:22 Get rid of a few more of these errors. 6:25 Starting to get much more manageable now. 6:26 So line ten, still problems with this line. 6:31 What's wrong? 6:34 Well, we need to put the bracket, opening brace it calls it, down here. 6:35 Line 14 is our next error. 6:41 The line numbers have changed, so let's update this. 6:43 Okay 15, there's a lot of problems on line 15. 6:47 We have four different errors with this one piece of code. 6:49 So let's take a look. 6:52 The static declaration must come after the visibility declaration. 6:53 Visibility declaration is public, private or protected. 6:58 So it means static, needs to go, there. 7:01 Once again, we have the same message, function abc bracket. 7:05 Not found, found abc space bracket. 7:09 So that's easily fixed. 7:11 Okay, getting there. 7:14 15, still more problems with 15. 7:17 This is a very controversial line. 7:19 Expected zero spaces between the opening bracket. 7:21 An argument bar, one found. 7:24 Expected zero spaces between argument bar and closing bracket, one found. 7:26 That means, it expected zero spaces here but found one, delete that space. 7:30 It expected, zero spaces there, but found one, so delete that. 7:36 And if we look down here it says, opening briefs should be on a new line. 7:41 So, that's simple. 7:44 Punt that down a line. 7:46 Go to the white space. 7:47 Let's run this again. 7:50 Okay. 7:53 White space found at end of line. 7:53 There's a few extra spaces there. 7:57 Get rid of that. 7:59 Inline control structures are not allowed. 8:00 Now if you're familiar, control structure is something like if, do, while. 8:03 And, inline means that it's all happening on the same line. 8:07 PHP allows you to do an inline control statement if there's only one 8:11 statement happening. 8:14 The problem is, if somebody does something like, then that 8:15 doesn't happen inside the IF. 8:21 That happens outside of the IF, which is very confusing. 8:22 So, to avoid any potential confusion, you just don't use inline control structures 8:26 [BLANK_AUDIO] 8:31 Okay. There's still problems with line 17. 8:35 Expected zero spaces and found one. 8:38 Get rid of that, and that. 8:39 Keep on running CodeSniffer. 8:43 And so we haven't got any errors left. 8:44 True, false, and no, must be lower cased. 8:46 Expected false but found capital F false. 8:49 So, someone used a weird style there. 8:52 Let's change that. 8:54 And you'll see that now PHP recognizes that as a, as a keyword instead. 8:55 On line, 18 we can see that its not been indented correctly, 9:00 because there is only two spaces. 9:02 They should be four. 9:04 Line 21. 9:06 Gotta get rid of these spaces. 9:06 Also on 21 true, false and null must be lowercased. 9:10 Again, someone's used caps lock instead, so we can change that. 9:12 Let's run CodeSniffer again. 9:17 It all fits on one screen now. 9:19 We're getting there. 9:20 Expected one space after the function key word. 9:22 Which line is this? 9:25 30. 9:26 Okay, so 9:27 when using a function when using an enormous function need to put a space in. 9:29 Also on 30, closing breaks must be on a line by itself. 9:33 Okay. 9:37 One new line at the end of a file. 9:39 Oh, we'll get to that in a second. 9:40 Each PHP statement must be in a line by itself. 9:42 We've still got a problem there. 9:45 Very close to having this complete now. 9:48 Expected one new line at the end of the file, found zero. 9:50 Okay? 9:53 There's an empty line. 9:54 The closing briefs for the class must go on the next line after the body. 9:56 What that means, is that the closing bracket for 9:59 the class, this, must be at the end of the body. 10:02 That's here. 10:05 So, delete that line. 10:06 Perfect! 10:10 All the errors are gone. 10:10 Many IDs and code editors will either have code sniffer built in. 10:13 Or available as a plug-in. 10:16 Using interactive tools like CodeSniffer, should really help you learn about PSR2. 10:18 You don't always need to follow PSR2 in your projects. 10:21 But it's slowly becoming far more common for people to do so. 10:25