topic Re: classes in Application Development and Automation Discussions

classes

Former Member — Mon, 22 Jan 2007 08:04:46 GMT

Hi All,

I want the differences between the public, private and protected classes with examples..Thanks in advance.

Re: classes

Former Member — Mon, 22 Jan 2007 08:17:56 GMT

Hi vijay,

1. Public attributes

Public attributes are defined in the PUBLIC section and can be viewed and changed from outside the class. There is direct access to public attributes. As a general rule, as few public attributes should be defined as possible.

PUBLIC SECTION.

DATA: Counter type i.

Public methods

Can called from outside the class

PUBLIC SECTION.

METHODS: set_attributes IMPORTING p_name(25) TYPE c,

p_planetype LIKE saplane-planetyp,

2. Private attributes

Private attributes are defined in the PRIVATE section. The can only be viewes and changed from within the class. There is no direct access from outside the class.

PRIVATE SECTION.

DATA: name(25) TYPE c,

planetype LIKE saplane-planetyp,

Private methods

Can only be called from inside the class. They are placed in the PRIVATE section of the class.

3.Protected components

When we are talking subclassing and inheritance there is one more component than Public and Private, the Protected component. Protected components can be used by the superclass and all of the subclasses. Note that Subclasses cannot access Private components.

Example

http://www.erpgenie.com/sap/abap/OO/eg.htm

Re: classes

uwe_schieferstein — Mon, 22 Jan 2007 08:23:06 GMT

Hello Vijay

Public classes can, obviously, instantiated by everybody.

Example: CL_GUI_ALV_GRID

For instantiating protected or private classes you will need a static CREATE method.

Example: CL_RECA_MESSAGE_LIST (created by calling CF_RECA_MESSAGE_LIST=>CREATE( ) ).

You will use the second approach if you want to specifically control the instantiating of your class.

Regards

Uwe

Re: classes

Former Member — Mon, 22 Jan 2007 09:28:27 GMT

Refer this link

http://help.sap.com/saphelp_47x200/helpdata/en/c3/225b5c54f411d194a60000e8353423/content.htm

http://help.sap.com/saphelp_nw04/helpdata/en/b3/f4b1406fecef0fe10000000a1550b0/content.htm

Message was edited by:

Judith Jessie Selvi

Re: classes

Former Member — Tue, 13 Feb 2007 18:56:43 GMT

Hi Vijay,

The class visibility refers to its instantiation: CREATE OBJECT.

As already mentioned in other replies but in a different way:

Public: CREATE OBJECT can be called from anywhere

Protected: CREATE OBJECT can be called from the class and its subclasses

Private: CREATE OBJECT can only be called from within the class

Abstract: CREATE OBJECT cannot be called at all.

Of course, I mean CREATE OBJECT variable_type_ref_to_the_class.

Private instantiation is typically used for the SINGLETON pattern where you allow only one instance of your class to exist. In such case, I always create a static method GET_INSTANCE() which returns the singleton instance of my class.

Abstract instantiation is used when a class represents an interface with a base implementation.

Protected instantiation is less common and used in particular cases.

Best regards,

Simon