TAW_12 Chapter 9, OO design patterns

Question 1

An ABSTRACT class or method has definition and implementation cannot be…

Answer 1

Instantiated

Question 2

Can a Static method be abstarct?

Answer 2

No, static methods cannot be redefined

Question 3

Both Classes and Methods can be _____ to prevent redefinition or inheritance

Answer 3

FINAL

Question 4

Can an ABSTRACT class be FINAL

Answer 4

Yes, but it should only contain static components

Question 5

How can a table of references be read using their public attributes?

Answer 5

table_line->fld = fld2

Question 6

SAP recommends limiting public attributes to what?

Answer 6

Read-only mode

Question 7

What does the addition table_line provide

Answer 7

Access to public attributes of the internal table object reference

Question 8

In the statement lcl_class = NEW what can be?

Answer 8

Either the super or subclass of the ref defined in the data statement

Question 9

Check this out!
data lcl_alv type ref to cl_gui_alv_grid.

lcl_alv = NEW #( i_parent = NEW cl_gui_custom_contatiner( conatiner_name = ‘CONTAINER_1’ ) )

Answer 9

Whoa! objects on the fly!!

Question 10

IS INSTANCE OF

Answer 10

Will determine if the object is type of the class or its subclasses

Question 11

CASE TYPE OF doe what?

Answer 11

Checks if the object is of a class type.  The when can be combined with an into
CASE TYPE OF CL_CAR.
When type cl_suv INTO lcl_suv

Question 12

Where does CREATE PRIVATE get declared and what does it mean?

Answer 12

At the Class Definition. It means an object can only be created within the class itself. Usually in a private static method of the class.

Question 13

What are the advantages of a factory method

Answer 13

It can handle a lot of coding (locks, auth checks, prereq code) without burdening the programmer
Multiple factory methods can exist for one class 
A factory method can choose to implement a suitable subclass if needed
A factory method can be managed by the class itself to prevent duplication (a group of singleton)

Question 14

One way to create a singleton is

Answer 14

Create PRIVATE
public section
class-method get_instance returning 
value(the_instance)
private section
data: keep_instance type ref to this_class)
method get_instance
if the_instance is initial.
   keep_instance = new #(this_class).
endif.
this_instance = keep_instance

Question 15

When a class declares a friendship, does it automatically become friends with the friend’s friends?

Answer 15

No

Question 16

Is a friend of a super class also a friend of the sub classes?

Answer 16

No

Question 17

In persistent objects the database access is performed by?

Answer 17

The class actor

Question 18

Can a tcode be linked to a public method of a class?

Answer 18

Yes, but the constructor cannot have importing parameters