Implementation Keyword
The implementation
section of a unit is required,
although it can be empty. The implementation
section contains the definitions of all functions, procedures, and
methods that are declared in the unit’s
interface
section. You can also have additional
type, subroutine, and variable declarations in the
implementation
section, in which case the
declarations are private to the
unit.
Changes to a unit’s implementation
section
do not force dependent units to be recompiled.
Any used units not needed for the interface
section should be listed in the uses
declaration
of the implementation
section. This minimizes the
amount of recompilation, should one of those units change. Changes to
the interface—including changes to used units—force a
recompilation of all dependent units. Changes to the implementation
section, on the other hand, do not propagate to dependent units.