Doubt in Abap code

Question

What is the meaning of the below statement
lo_desc ?= <ls_descriptor>-descriptor.

Answer 1

Hi,
Like class references, you can assign interface references to different reference variables. You can also make assignments between class reference variables and interface reference variables. When you use the MOVE statement or the assignment operator (=) to assign reference variables, the system must be able to recognize in the syntax check whether an assignment is possible.
Suppose we have a class reference <cref> and interface references <iref>, <iref1>, and <iref2>. The following assignments with interface references can be checked statically:
<iref1> = <iref2>
Both interface references must refer to the same interface, or the interface of <iref1> must contain the interface <iref2> as a component.
<iref> = <cref>
The class of the class reference <cref> must implement the interface of the interface reference <iref>.
<cref> = <iref>
The class of <cref> must be the predefined empty class OBJECT.
In all other cases, you would have to work with the statement MOVE ...? TO or the casting operator (?=). The casting operator replaces the assignment operator (=). In the MOVE... ? TO statement, or when you use the casting operator, there is no static type check. Instead, the system checks at runtime whether the object reference in the source variable points to an object to which the object reference in the target variable can also point. If the assignment is possible, the system makes it, otherwise, the catchable runtime error MOVE_CAST_ERROR occurs.
You must always use casting for assigning an interface reference to a class reference if <cref> does not refer to the predefined empty class OBJECT:
<cref> ?= <iref>
For the casting to be successful, the object to which <iref> points must be an object of the same class as the type of the class variable <cref>.