Type Perfect

Next level type declaration check PHPStan rules.

We use these sets to improve code quality of our clients' code beyond PHPStan features.

• These rules make skipped object types explicit, param types narrow and help you to fill more accurate object type hints.
• They're easy to enable, even if your code does not pass level 0
• They're effortless to resolve and make your code instantly more solid and reliable.

If you care about code quality and type safety, add these 10 rules to your CI.

Install

composer require rector/type-perfect --dev

Note: Make sure you use phpstan/extension-installer to load the necessary service configs or include vendor/rector/type-perfect/config/extension.neon file.

There are 2 checks enabled out of the box. First one makes sure we don't miss a chance to use instanceof to make further code know about exact object type:

private ?SomeType $someType = null;

if (! empty($this->someType)) {
    // ...
}

if (! isset($this->someType)) {
    // ...
}

// here we only know, that $this->someType is not empty/null

🙅

↓

if (! $this->someType instanceof SomeType) {
    return;
}

// here we know $this->someType is exactly SomeType

✔️

Second rule checks we use explicit object methods over magic array access:

$article = new Article();

$id = $article['id'];
// we have no idea, what the type is

🙅

↓

$id = $article->getId();
// we know the type is int

✔️

Configure

Next rules you can enable by configuration. We take them from the simplest to more powerful, in the same order we apply them on legacy projects.

You can enable them all at once:

parameters:
    type_perfect:
        no_mixed_property: true
        no_mixed_caller: true
        null_over_false: true
        narrow_param: true
        narrow_return: true

Or one by one:

1. Null over False

parameters:
    type_perfect:
        null_over_false: true

Bool types are typically used for on/off, yes/no responses. But sometimes, the false is misused as no-result response, where null would be more accurate:

public function getProduct()
{
    if (...) {
        return $product;
    }

    return false;
}

🙅

↓

We should use null instead, as it enabled strict type declaration in form of ?Product since PHP 7.1:

public function getProduct(): ?Product
{
    if (...) {
        return $product;
    }

    return null;
}

✔️

2. No mixed Property

parameters:
    type_perfect:
        no_mixed_property: true

This rule focuses on PHPStan blind spot while fetching a property. If we have a property with unknown type, PHPStan is not be able to analyse it. It silently ignores it.

private $someType;

public function run()
{
    $this->someType->vale;
}

It doesn't see there is a typo in vale property name. It should be value

🙅

↓

private SomeType $someType;

public function run()
{
    $this->someType->value;
}

This rule makes sure all property fetches know their type they're called on.

✔️

3. No mixed Caller

parameters:
    type_perfect:
        no_mixed_caller: true

Same as above, only for method calls:

private $someType;

public function run()
{
    $this->someType->someMetho(1, 2);
}

It doesn't see there is a typo in someMetho name, and that the 2nd parameter must be string.

🙅

↓

private SomeType $someType;

public function run()
{
    $this->someType->someMethod(1, 'active');
}

This group makes sure methods call know their type they're called on.

✔️

4. Narrow Param Types

The more narrow param type we have, the reliable the code is. string beats mixed, int beats scalar and ExactObject beats stdClass.

parameters:
    type_perfect:
        narrow_param: true

In case of private, but also public method calls, our project often knows exact types that are passed in it:

// in one file
$product->addPrice(100.52);

// another file
$product->addPrice(52.05);

But out of from fear and "just to be safe", we keep the addPrice() param type empty, mixed or in a docblock.

🙅

↓

If, in 100 % cases the float type is passed, PHPStan knows it can be added and improve further analysis:

-/**
- * @param float $price
- */
-public function addPrice($price)
+public function addPrice(float $price)
{
    $this->price = $price;
}

That's where this group comes in. It checks all the passed types, and tells us know how to narrow the param type declaration.

✔️

5. Narrow Return Types

Last but not least, the more narrow return type, the more reliable the code.

parameters:
    type_perfect:
        narrow_return: true

Where does it help? Let's say we have 2 types of talks, that do have different behavior:

final class ConferenceTalk extends Talk
{
    public function bookHotel()
    {
        // ...
    }
}

final class MeetupTalk extends Talk
{
    public function bookTrain()
    {
        // ...
    }
}

Then we have a factory (repository, or services) that returns generic Talk type:

final class TalkFactory
{
    public function createConferenceTalk(): Talk
    {
        return new ConferenceTalk();
    }

    public function createMeetupTalk(): Talk
    {
        return new MeetupTalk();
    }
}

In this case we've just lost strict type and have to verify the type on runtime:

$talk instanceof ConferenceTalk

🙅

↓

That's where this group comes in. In case we return the exact type, we should use exact type in return type declaration to keep the code as reliable as possible:

 final class TalkFactory
 {
-    public function createConferenceTalk(): Talk
+    public function createConferenceTalk(): ConferenceTalk
     {
         return new ConferenceTalk();
     }

-    public function createMeetupTalk(): Talk
+    public function createMeetupTalk(): MeetupTalk
     {
         return new MeetupTalk();
     }
}

✔️

Add sets one by one, fix what you find helpful and ignore the rest.

Happy coding!