User defined types

User defined types help to centralize the definition of complex structured data types.

A user defined type is created with the TYPE keyword. The next code example defines a type as a dynamic array of a record, with the structure of a database table as defined in the mydbschema.sch schema file:

SCHEMA mydbschema
...
TYPE t_custlist DYNAMIC ARRAY OF RECORD LIKE customer.*

Variables can then be defined with the "custlist" user defined type:

DEFINE cl t_custlist

The scope of a type can be global, local to a module or local to a function.

Variables can be defined with a type defined in the same scope, or in a higher level of scope.

A typical usage is to declare user-defined types as PUBLIC in a module, so they can be reused in other modules:

The myutils.4gl module defines the user type:

PUBLIC TYPE t_item_info RECORD
        id INTEGER,
        description VARCHAR(100),
        creation DATE,
        mandatory BOOLEAN,
        ...
    END RECORD
...

In the module importing the utility module, define variables using the type name, with utility module as prefix:

IMPORT FGL myutils
...
  DEFINE itemlist DYNAMIC ARRAY OF myutils.t_item_info
...