PHP
ReflectionMethod
Learn a method's parameters, visibility and return type with ReflectionMethod.
Inspect a method with ReflectionMethod
ReflectionMethod inspects a single method. new ReflectionMethod("UserService", "find") gives you the find method.
getParameters() returns a ReflectionParameter for each parameter; getName() returns the parameter name. isPublic(), isPrivate(), isProtected() describe visibility, getReturnType() the return type.
You can therefore use a third-party class without docs: parameter names and types are right there.
Inspect a parameter with ReflectionParameter
Each ReflectionParameter mirrors one parameter. getName() returns the name, getType() the type, isOptional() whether it is optional.
Optional parameters expose their default via getDefaultValue(); but first check isDefaultValueAvailable() to avoid surprises.
With this data, for example, a CLI tool can build options from parameter names.
Exercise Print the find method's parameters
The UserService::find method is given. Build a ReflectionMethod instance and print each parameter's name on a separate line using getParameters().
Show example solution
Build $rm = new ReflectionMethod("UserService", "find");. Print with foreach ($rm->getParameters() as $param) { echo $param->getName() . "\n"; }.
Example solution:
<?php
class UserService {
public function find(int $id, ?string $field = null): ?array {
return null;
}
}
$rm = new ReflectionMethod("UserService", "find");
foreach ($rm->getParameters() as $param) {
echo $param->getName() . "\n";
}
Test yourself
-
Match ReflectionMethod methods
- getParameters
- Returns the parameter list
- isPrivate
- Asks whether it is private
- getReturnType
- Returns the return type
- getName
- Returns the method name
-
What does new ReflectionMethod("UserService", "find") return?
- All methods of the UserService class
- All parameters of the find method
- A ReflectionMethod object representing find
- The return type of the find method
Show answer
A ReflectionMethod object representing find — Correct. You get a ReflectionMethod for that single method.
-
Loop with getParameters()
<?php
$rm = new ReflectionMethod("UserService", "find");
foreach ($rm->____() as $param) {
echo $param->getName() . "\n";
}
Show answer
<?php
$rm = new ReflectionMethod("UserService", "find");
foreach ($rm->getParameters() as $param) {
echo $param->getName() . "\n";
}
Next lesson: ReflectionProperty
