Type Assertions

Type assertions verify that values match expected PHP types.

Available Assertions

integer()

Assert that a value is a PHP integer.

use Cline\Assert\Assertions\Assertion;

Assertion::integer($count);
Assertion::integer($id, 'ID must be an integer');

float()

Assert that a value is a PHP float.

Assertion::float($price);
Assertion::float($temperature, 'Temperature must be a float');

string()

Assert that a value is a string.

Assertion::string($name);
Assertion::string($email, 'Email must be a string');

boolean()

Assert that a value is a PHP boolean.

Assertion::boolean($isActive);
Assertion::boolean($flag, 'Flag must be a boolean');

numeric()

Assert that a value is numeric (int, float, or numeric string).

Assertion::numeric($value);
Assertion::numeric($amount, 'Amount must be numeric');

integerish()

Assert that a value is an integer or can be cast to an integer.

Assertion::integerish('123');  // Passes
Assertion::integerish(123);    // Passes
Assertion::integerish('123.0'); // Fails

scalar()

Assert that a value is a PHP scalar.

Assertion::scalar($value);
Assertion::scalar($input, 'Input must be scalar');

isArray()

Assert that a value is an array.

Assertion::isArray($items);
Assertion::isArray($config, 'Config must be an array');

isObject()

Assert that a value is an object.

Assertion::isObject($instance);
Assertion::isObject($model, 'Model must be an object');

isResource()

Assert that a value is a resource.

$file = fopen('file.txt', 'r');
Assertion::isResource($file);

isCallable()

Assert that a value is callable.

Assertion::isCallable($callback);
Assertion::isCallable(fn() => true);
Assertion::isCallable('strlen');
Assertion::isCallable([$object, 'method']);

Chaining Type Assertions

use Cline\Assert\Assert;

Assert::that($age)
    ->integer()
    ->greaterThan(0);

Assert::that($name)
    ->string()
    ->notEmpty();

Common Patterns

Input Validation

Assert::that($userId)
    ->integer('User ID must be an integer')
    ->greaterThan(0, 'User ID must be positive');

Numeric Type Checking

// Strict integer check
Assert::that($count)->integer();

// Flexible numeric check
Assert::that($amount)->numeric();

// Integer-like check
Assert::that($id)->integerish();

Type Coercion vs Strict Types

Strict Type Checking

Assertion::integer(123);     // Pass
Assertion::integer('123');   // Fail
Assertion::integer(123.0);   // Fail

Flexible Type Checking

Assertion::numeric(123);     // Pass
Assertion::numeric('123');   // Pass
Assertion::numeric(123.45);  // Pass

Assertion::integerish(123);      // Pass
Assertion::integerish('123');    // Pass
Assertion::integerish(123.0);    // Fail

Best Practices

Be Specific

// Too loose
Assertion::scalar($age);

// Specific
Assertion::integer($age);

Chain Related Assertions

Assert::that($email)
    ->string()
    ->notEmpty()
    ->email();

Use Integerish for Flexible Input

Assert::that($_POST['quantity'])
    ->integerish()
    ->greaterThan(0);

Next Steps

• Numeric Assertions - Number validation
• Object Assertions - Object validation
• Array Assertions - Array validation