Data Dictionary field information is stored and accessed using a field interface. This interface requires that you pass a field identifier and sometimes a table identifier as parameters. These parameters must be passed as integer values. Special keywords, Field and File_Field, are provided that allow you to pass these parameters as names instead of numbers. The compiler will convert these to the appropriate number constants. Examples of this keyword usage are:
// use of the field keyword
Get Field_Current_Value of oCustomer_DD Field Customer.Name to sName
Set Field_Changed_Value of oCustomer_DD Field Customer.Name to sName
// use of the File_Field keyword
Get File_Field_Current_Value of oOrder_DD File_Field SalesP.Name to sName
Set File_Field_Changed_Value of oOrder_DD File_Field SalesP.Name to sName
The Field keyword is used with the Field style messages. You use these when the Data Dictionary Object receiving the message “owns” the field. In the above example, Customer.Name is defined within the oCustomer_DD DDO.
The File_Field keyword is used with the File_Field style messages. You use these when the Data Dictionary Object receiving the message may not “own” the field – the field may be owned by the DDO or by one of its parent DDOs. In the above example, SalesP.Name is defined within the oOrder_DD DDO but the field is “owned” by the parent DDO, oSales_DD. File_Field is used in such a case and the DDO will redirect the message to the appropriate DDO.
The File_Field and Field keywords are discussed in greater detail in Understanding the File_Field and Field Keywords.