php-strictus/strictus
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Last Updated: 2023-06-28 12:28:06
Strict Typing on inline variables for PHP
License:
Languages: PHP, Makefile, Dockerfile
Strictus
Strict Typing for local variables in PHP
Introduction
Strictus brings strict typing for local variables into PHP.
With Strictus, you can control the types of local variables using different patterns.
💣 The problem:
PHP has no support for strongly typed Local Variables.
Here is an illustrative example of a basic mistake:
<?php
//Rule: Active discount of 10% or 25% for orders from $50
$total = 82.50;
$discount = 0.10; //float
if ($total >= 50) {
$discount = '25%'; //replacing a float value with string value 🤦🏻♂️
}
$total = $total - ($total * $discount); //💥 Error: A float cannot be multiplied by a stringIn the code above, nothing prevents overriding the float value of $discount a string value, causing a bug.
👍 The solution:
Let's rewrite the previous example using Strictus and strongly typed variables:
<?php
//Rule: Active discount of 10% or 25% for orders from $50
use Strictus\Strictus;
$total = Strictus::float(82.50);
$discount = Strictus::float(0.10);
if ($total() >= 50) {
$discount(0.25); //updates the $discount value
}
$total($total() - ($total() * $discount()));
echo $total(); //61.875In the code above, the variable $discount is an instance of StrictusFloat::class and it only accepts float values.
An Exception StrictusTypeException is thrown when we try to assign anything that is not of type float, like a string for example.
See this example:
<?php
use Strictus\Strictus;
$discount = Strictus::float(0.10);
$discount('25%'); //A StrictusTypeException stops the code executionInstallation
You can install the package via composer:
composer require strictus/strictusRequires: PHP 8.1+
Usage
There are a few different patterns you can use to work Strictus.
Creating Your Variables
To create a variable, simply call Strictus::*method*(), replacing the *method* with the type you want to enforce.
For example:
<?php
use Strictus\Strictus;
//creates a string
$name = Strictus::string('Wendell');
//creates a nullable string
$comment = Strictus::nullableString(null);
//creates an int
$score = Strictus::int(100);
//creates a boolean
$isActive = Strictus::boolean(true);
//creates an array
$authors = Strictus::array(['Wendell', 'Christopher']);
//creates an object
$person = Strictus::object((object) ['name' => 'Wendell', 'country' => 'BR']);
//instantiates a class
$calculator = Strictus::instance(CalculatorClass::class, new CalculatorClass());
//instantiates an enum
$role = Strictus::enum(Role::class, Role::CONTRIBUTOR);
class CalculatorClass
{
//...
}
enum Role
{
case CONTRIBUTOR;
}💡 Check out all the available variable methods.
Getting Variable Value
To retrieve the variable value, just call it like a function:
echo $name(); //Wendell
echo $score() - 10; //90
if ($isActive()) {
//do your logic here
}
echo implode($authors(), ';'); //Wendell;ChristopherAlternatively, you can use the $variable like a Value Object:
$name = Strictus::string('Christopher'); //creates a string
echo $name->value; //ChristopherUpdate Variable Value
To update the variable value, call it like a function passing the new value as the argument:
$score = Strictus::int(100);
$score($score() - 20); //updates $score
echo $score(); //80Alternatively, you can use the $variable like a Value Object:
$score = Strictus::int(100);
$score->value = 0;
echo $score(); //0Variable methods
You can use the following methods to create single type variables:
| Type | Nullable | Method |
|---|---|---|
| String | No | Strictus::string($value) |
| String | Yes | Strictus::string($value, true) |
| String | Yes | Strictus::nullableString($value) |
| Integer | No | Strictus::int($value) |
| Integer | Yes | Strictus::int($value, true) |
| Integer | Yes | Strictus::nullableInt($value) |
| Float | No | Strictus::float($value) |
| Float | Yes | Strictus::float($value, true) |
| Float | Yes | Strictus::nullableFloat($value, true) |
| Boolean | No | Strictus::boolean($value) |
| Boolean | Yes | Strictus::boolean($value, true) |
| Boolean | Yes | Strictus::nullableBoolean($value) |
| Array | No | Strictus::array($value) |
| Array | Yes | Strictus::array($value, true) |
| Array | Yes | Strictus::nullableArray($value) |
| Object | No | Strictus::object($value) |
| Object | Yes | Strictus::object($value, true) |
| Object | Yes | Strictus::nullableObject($value) |
| Class Type | No | Strictus::instance($instanceType, $value) |
| Class Type | Yes | Strictus::instance($instanceType, $value, true) |
| Class Type | Yes | Strictus::nullableInstance($instanceType, $value) |
| Enum Type | No | Strictus::enum($enumType, $value) |
| Enum Type | Yes | Strictus::enum($enumType, $value, true) |
| Enum Type | Yes | Strictus::nullableEnum($enumType, $value) |
Union Types
Strictus also supports union types:
use Strictus\Enums\Type;
$unionTypesVariable = Strictus::union([Type::INT, Type::STRING], 'foo');
echo $unionTypesVariable->value; //foo
echo $unionTypesVariable(); //foo
// Update variable
$unionTypesVariable->value = 100;
echo $unionTypesVariable->value; //100
// Thrown an exception if the value is wrong union types
$unionTypesVariable->value = false; //StrictusTypeExceptionImmutable Variables
If you want to create immutable variables, you can use the ->immutable() method. If you try to assign a new value
to an Immutable Variable, an Strictus\Exceptions\ImmutableStrictusException exception will be thrown:
$immutableScore = Strictus::int(100)->immutable();
$immutableScore(50); //ImmutableStrictusException
$immutableScore->value = 50; //ImmutableStrictusExceptionError Handling
If you try to assign a value that doesn't match the type of the created variable, an
Strictus\Exceptions\StrictusTypeException exception will be thrown:
$score = Strictus::int(100);
$score('one hundred'); //StrictusTypeException
$score->value = false; //StrictusTypeExceptionIf you try to assign a new value to an Immutable Variable, an
Strictus\Exceptions\ImmutableStrictusException exception will be thrown:
$immutableScore = Strictus::int(100)->immutable();
$immutableScore(50); //ImmutableStrictusException
$immutableScore->value = 50; //ImmutableStrictusExceptionMotivation
Following a discussion on Twitter between Christopher Miller and Wendell Adriel around the lack of strongly typed local variables for PHP we quickly decided a package was the right approach whilst we could get an RFC into the core.
Credits
Contributing
We welcome contributions!
Please visit the Contributing Guide to learn more about contributing to Strictus.