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PHP Standards and Best Practices

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Autoloading

3:03 with Phil Sturgeon

Autoloading is the art of only loading what you actually need. It is done very efficiently in PHP, and when a class is requested you can register an autoloader to then locate and include the class for you. When combined with an autoloading standard such as PSR-0 or PSR-4 this is very simple.

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    Autoloading is one of [UNKNOWN] most useful features when it comes to 0:00
    object-oriented code. 0:03
    Gone are the days of being forced to include a huge list of code on 0:04
    the off chance that later, some of your code might need it. 0:07
    All you need to do is register an autoloader, 0:11
    then make sure your autoloader and file wants to use the same rules. 0:13
    Let's take a look at how we might make our own autoloader. 0:16
    Let's take the code from our last lesson and adopt it to use auto loading. 0:19
    Auto loading is important because as our application grows it 0:23
    seems only logical that the code we depend on grows too. 0:25
    As we develop, we'll most likely have more than just HTTP and 0:29
    Twitter but all sorts of other includes too. 0:32
    To save us including each of them manually, let's make our own auto 0:35
    loader allowing other developers or future you to add dependencies easily. 0:37
    Let's tuck this autoloader away in a bootstrap file to keep our index 0:42
    nice and clean. 0:45
    We go to our workspace, and add new file. 0:47
    We can just create bootstrap.php and we'll just shove it in the root here. 0:51
    Then the code that we enter will look like this. 0:55
    Here we can see an autoloader being registered with an anonymous function. 0:58
    The anonymous function acts as a call back. 1:02
    Basically whenever a class is referenced the PHP does not recognize it will 1:05
    hit this callback and pass the name of the class in as a string argument, 1:09
    which we can see here on line three. 1:13
    Our callback then accepts that string as an argument. 1:15
    Line four will replace any back slashes with a forward slash. 1:18
    PHP knows this means a directory separator regardless of your operating system. 1:21
    The reason we have two backslashes in the first argument is that only putting one 1:26
    backslash in here would escape the single quote, and that'll cause a syntax error. 1:29
    So we take one of these slashes out here, 1:33
    you see the syntax is all changed, and that is broken. 1:34
    So you need two backslashes here. 1:37
    We then create a new string starting with the current directory. 1:40
    Appending the source src folder, and use that new class name and 1:43
    suffix dot PHP on the end of the string to make a full file path. 1:47
    Now we include this file, otherwise PHP won't know how to use it. 1:52
    Let's go back to index.php and put this all together. 1:55
    So, we no longer need to include these files manually, so 1:59
    we can delete this line. 2:02
    And we can change this include here so instead of including one 2:02
    of the classes directly we can say that we'd like to include bootstrap. 2:07
    Let's try having a look at this in preview mode and see if it worked. 2:11
    Perfect. 2:16
    Even though we did not explicitly include the classes we wanted as we did in 2:17
    the last lesson, PHP is still happy because it knows where to find the code. 2:20
    Now, it's important to have a base understanding of making your 2:24
    own autoloaders. 2:27
    But it might not always be a great idea to roll your own. 2:28
    For years, autoloading code in PHP was a bit hit or miss. 2:31
    And this was down to everyone wanting to write their own auto-loaders and 2:35
    organizing their code in their own different ways. 2:37
    This meant implementing 10 different packages could mean 10 different styles of 2:40
    auto-loading being used. 2:44
    These days, we have the PSL zero standard and a new and shiny standard called PSL 4. 2:46
    These two standards were written by the PHP Framework Interoperability Group, 2:51
    to make autoloading dependencies incredibly easy. 2:55
    We'll look more at how PSR4 works with Composer in the upcoming lessons. 2:59

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