Global Classes vs Local Classes

Explanation

Local classes are defined inside a program and are useful when the logic is needed only within that program. Global classes are created in the class builder and can be reused across reports, interfaces, enhancements and services. A local class is good for organizing report-specific logic. A global class is better when the logic is reusable, testable and part of a broader design. Choosing between local and global class depends on reuse, ownership, transport impact and maintainability.

Code example

CLASS lcl_report_helper DEFINITION.  PUBLIC SECTION.    METHODS build_field_catalog.ENDCLASS. CLASS lcl_report_helper IMPLEMENTATION.  METHOD build_field_catalog.    " Report-specific helper logic  ENDMETHOD.ENDCLASS.

Real project scenario

A report-specific ALV layout helper can be a local class. But a customer validation service used by multiple reports, BAPIs and OData services should be a global class.

Common mistakes

- Creating global classes for one-time local logic. - Keeping reusable logic hidden inside local classes. - Creating global utility classes with unrelated methods. - Not considering transport and ownership.

Best practices

- Use local classes for report-specific structure. - Use global classes for reusable business logic. - Avoid dumping unrelated methods into one class. - Design global classes with stable interfaces.

Interview angle

A good answer should explain reuse boundary: local class for program-specific logic, global class for reusable business/service logic.