Adding Arguments to Our Functions¶

We already know that functions can have arguments - we just saw that with header, which has one argument. We can make save_pets require an argument too - just add a $petsToSave variable between the parenthesis of that function:

function save_pets($petsToSave)
{
    $json = json_encode($pets, JSON_PRETTY_PRINT);
    file_put_contents('data/pets.json', $json);
}

Now, call the function from pets_new.php. When we do, PHP will require us to pass it an argument. Give it the $pets variable:

$pets[] = $newPet;

save_pets($pets);

header('Location: /');
die;

Accessing an Argument from inside a Function¶

Ok, now dump $petsToSave so we can see what’s going on:

function save_pets($petsToSave)
{
    var_dump($petsToSave);die;
    $json = json_encode($pets, JSON_PRETTY_PRINT);
    file_put_contents('data/pets.json', $json);
}

Fill out the form. Bam! We see the big pets array. Change the argument to save_pets to just a little bit of text:

$pets[] = $newPet;

save_pets('this is some text!');

header('Location: /');
die;

Refresh! Now our text is dumped out. So whatever we pass to save_pets becomes the $petsToSave variable. Change the argument back to $pets:

$pets[] = $newPet;

save_pets($pets);

header('Location: /');
die;

Inside save_pets, we can pass $petsToSave into json_encode. Oh, and I just invented this variable name - we could have called it anything:

function save_pets($petsToSave)
{
    $json = json_encode($petsToSave, JSON_PRETTY_PRINT);
    file_put_contents('data/pets.json', $json);
}

Moment of truth! Refresh. We’re back on the homepage with the pet we just added. Brilliant!

Why Use Functions?¶

Things work the same as before, so why did I make you add this function? Moving logic into functions gives us 2 really cool things.

First, if we need to save pets somewhere else, we can just re-use this function. We’re already doing this with get_pets, which I think we’re calling in at least 3 places.

Second, by moving these lines into a function with a name, it helps explain what they do. If I didn’t write this code, I might have trouble figuring out what it does or its purpose. But when it’s inside a function called save_pets, that helps.

We’ll go through this process of writing code and reorganizaing it over and over again. Our site is measured by more than just whether or not it works: you also want your code to be easy to understand and easy to make more changes too.

Building great things and doing it well, that’s where you’re going. And you’ve just finished another episode you crazy developer! Congrats! Now build something and keep learning with us.

Seeya next time!