Take Test: Symfony 7 – PHP – Traits

Question 1: What problem do traits solve in PHP OOP?

They provide multiple inheritance of classes.

They allow sharing method implementations across unrelated classes.

They are a special kind of interface.

They are a replacement for namespaces.

Question 2: How do you include a trait inside a class?

Extend the trait: class A extends T {}

Import with include "T.php";

Annotate with #[Use(T)].

Use the use keyword inside the class body: class A { use T; }.

Question 3: If a method exists in a class, a trait, and a parent class, which one is used?

The trait method overrides the class and parent.

The method defined in the class overrides the trait and parent.

The parent class method overrides both.

Whichever was declared first in time.

Question 4: Two traits define the same method. How do you resolve the conflict?

With insteadof (and optionally as for alias).

With switch/case inside the traits.

By declaring the class final.

By importing only one with use_once.

Question 5: Can you change the visibility of a trait method when using it in a class?

No, trait method visibility is fixed.

Only to public, never to protected/private.

Yes, using as with a visibility modifier (e.g., as protected).

Only for static methods.

Question 6: Which statement about traits is TRUE?

Traits can be instantiated directly.

Traits support class inheritance.

Traits must always implement interfaces.

Traits cannot be instantiated or extended like classes.

Question 7: Can traits define properties in PHP?

No; traits cannot have properties.

Yes; conflicting property definitions cause a fatal error.

Only static properties are allowed.

Only private properties are allowed.

Question 8: What is the effect of declaring abstract methods inside a trait?

They require the using class to implement those methods.

They are ignored at runtime.

They make the trait instantiable.

They convert the trait into an interface.

Question 9: Can a trait use other traits?

Yes, traits can use other traits.

No, only classes can use traits.

Only if the trait is final.

Only when the trait has no methods.

Question 10: What will this print? trait T{public function hi(){echo "hi";}} class A{use T;} (new A)->hi();

Nothing

Trait

Fatal error

hi

Question 11: Given: trait A{function x(){return "A";}} trait B{function x(){return "B";}} class C{use A,B { A::x insteadof B; B::x as y; }} What does (new C)->x().(new C)->y() return?

AA

AB

BA

BB

Question 12: Which kinds of methods can traits define?

Only instance methods.

Only static methods.

Both instance and static methods.

Only abstract methods.

Question 13: Inside a trait, what does self refer to at runtime?

The trait itself.

Always the parent of the using class.

A special internal trait type.

The class that uses the trait.

Question 14: Can a trait define __construct, and what if the class already has one?

Yes; the class constructor takes precedence over the trait's one.

No; traits cannot define constructors.

Yes; the trait always overrides the class.

Yes; but only if the class is abstract.

Question 15: Are constants allowed in traits in PHP 8.2+?

No, traits can never declare constants.

Only interfaces can declare constants.

Yes, traits can declare constants since PHP 8.2.

Only abstract classes can declare constants.

Question 16: What happens if two used traits declare the same property with different definitions?

First trait wins silently.

Fatal error due to conflicting property definitions.

Second trait wins silently.

PHP auto-renames the properties.

Question 17: Why do teams often extract cross-cutting behavior into traits?

To reuse the same behavior across many classes without duplication.

To replace autoloaders.

To force a single inheritance chain.

To avoid using interfaces.

Question 18: Given trait T{public function run(){}} class A{ use T { run as protected doRun; } } Which calls are valid?

Outside code can call doRun() directly.

Neither run() nor doRun() can be called.

Both are public after aliasing.

Outside code can call run(), but not doRun().

Question 19: Inside a trait, what does static:: call use for binding?

The trait's own static context.

Always the parent class.

Late static binding of the consuming class.

A fixed base class chosen at compile time.

Question 20: If two traits added to a class define the same method and you do not resolve it, what happens?

A fatal error occurs unless you resolve with insteadof/as.

PHP picks the first trait automatically.

PHP picks the last trait automatically.

The class method is created as an empty stub.