OOP Basics III

Question 1

Which overrides? The methods of a trait, or similarly-named inherited methods of a parent class?

Answer 1

Methods of a trait.

Question 2

Which overrides? The methods of a class, or similarly-named methods of a trait?

Answer 2

Methods of a class.

Question 3

What is the ‘insteadof’ keyword?

Answer 3

‘Insteadof’ is used to specify which trait’s methods should be used in a name conflict.

Question 4

What is the ‘as’ keyword?

Answer 4

‘as’ is used to assign alias names to conflicting trait methods.

Question 5

Can traits access private properties or methods of composing classes?

Answer 5

Yes.

Question 6

Can composing classes access the private methods and properties of traits?

Answer 6

Yes.

Question 7

Traits are essentially language-assisted __ _ __.

Answer 7

copy and paste

Question 8

Can traits include abstract methods?

Answer 8

Yes.

Question 9

Traits are a mechanism for __ __ in single inheritance languages.

Answer 9

code reuse

Question 10

Can you instantiate a trait on its own?

Answer 10

No.

Question 11

Traits are the application of class members without requiring __.

Answer 11

inheritance

Question 12

How do you insert multiple traits into a class?

Answer 12

As a comma-separated list.

Question 13

What happens when two traits insert a method with the same name?

Answer 13

A fatal error is produced.

Question 14

The ‘as’ syntax can also be used to adjust…

Answer 14

…the visibility of a method.

Question 15

Static variables can be referred to in trait methods, but cannot be __ _ _ __.

Answer 15

defined by the trait

Question 16

Can traits define static methods for the exhibiting class?

Answer 16

Yes.

Question 17

Avoid using ‘as’ on a…

Answer 17

…__construct() method.

Question 18

How can you iterate through all visible properties in a class?

Answer 18

$class = new MyClass();
foreach($class as $key=>$value) { ... }

Question 19

How can you iterate through non-visible properties in a class?

Answer 19

Within the class definition:

foreach($this AS $key=>$value) { … }

Question 20

Can a property be declared as final?

Answer 20

No. Only classes and methods.