3/14/2011. 1. Spring 2011. Enterprise Programming. ABAP OBJECTS, PART 2.
Discussion Topics. ✓ Working with static method and attributes. ✓ Object ...
3/14/2011
ABAP OBJECTS, PART 2
Spring 2011
Enterprise Programming
Discussion Topics Working with static method and attributes Object Instantiation
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Working with classes in programs Classes, when instantiated, become objects. Not all classes need to be instantiated to be used within programs. Static attributes (CLASS-DATA) Static methods (CLASS-METHODS) To reference a static public attribute: classname=>attributename myvar = classname=>attributename To call a static method: CALL METHOD classname=>methodname. "traditional classname=>methodname( ). "as of Web AS 6.10 Static vs. instance: Static uses => Instance uses -> Other syntax elements are the same.
Calling methods Cannot be a space before opening parenthesis. Must be one after. If only one importing parameter in method definition, list the actual parameter in the parenthesis by listing data object name only. class=>method( data1 ). If several importing parameters, parameters must be listed in pairs: formal parameter = actual parameter. class=>method( par1 = data1 par2 = data2 ). If there are parameters of types other than importing, the type of parameter passing must be listed. class=>method( EXPORTING p1 = d1 p2 = d2 IMPORTING par3 = data3 CHANGING par4 = data4 ).
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Calling methods Functional methods (those that return a value) The value to be returned by be listed in the method call interface using the parameter passing type RECEIVING. class=>method( IMPORTING p1 = d1 RECEIVING par4 = data4 ). The value to be returned may be captured through assignment (more typical). data3 = class=>method( d1 ).
Calling methods Parameter passing types defined in the method definition correspond to parameter passing types in the caller but are not the same. Method Definition
Method Call
IMPORTING
EXPORTING
EXPORTING
IMPORTING
CHANGING
CHANGING
RETURNING
RECEIVING
I am exporting a value to you Method Call
I am importing a value from you Method Definition
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Let's Practice
Static Rules Static methods can only access static attributes. Static method may define local data objects. Instance methods can access static and instance attributes.
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Object Creation Objects are created by defining an object reference variable and then creating the object. The START-OF-SELECTION keyword indicates where the runtime environment should begin control flow. * Object definitions here START-OF-SELECTION. DATA objectname TYPE REF TO classname. CREATE OBJECT objectname.
Copyrights Presentation prepared by and copyright of Dr. Tony Pittarese, East Tennessee State University, Computer and Information Sciences Dept. (
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