Passing records by reference
With CALL func(record-name.*)
, RECORD
structures are passed to functions by copying all record members on the stack.
All record members are also copied on the stack, when returning a complete record from a function
with RETURN record-name.*
If the record is big, this can lead to performances issues when the function is called many
times, or when chaining function calls passing complete records to each other. This is even more
resource consuming, when using CHAR()
types.
To improve performances, you can pass records by reference to functions: To pass the reference
of a record to a function, define the function with the INOUT
keyword for the
record parameter. With this solution, records of the caller can be modified in the function (there
is no need to return the record). When calling the function, only specify the record name.
TYPE
instruction, as well as fully typed
function definitions.The next code example shows the execution time improvement when passing a record by reference:
TYPE t_cust RECORD
cust_id INTEGER,
cust_name CHAR(100),
cust_addr CHAR(2000)
END RECORD
MAIN
CONSTANT MAXCNT = 1000000
DEFINE cust t_cust
DEFINE ts DATETIME HOUR TO FRACTION(5)
DEFINE x INTEGER
LET cust.cust_id = 101
LET cust.cust_name = "xxx"
LET cust.cust_addr = "zzz"
LET ts = CURRENT
FOR x=1 TO MAXCNT
CALL func1( cust.* ) RETURNING cust.*
END FOR
DISPLAY CURRENT HOUR TO FRACTION(5) - ts
LET ts = CURRENT
FOR x=1 TO MAXCNT
CALL func2( cust )
END FOR
DISPLAY CURRENT HOUR TO FRACTION(5) - ts
END MAIN
FUNCTION func1( rec )
DEFINE rec t_cust
CALL func11( rec.* ) RETURNING rec.*
RETURN rec.*
END FUNCTION
FUNCTION func11( rec )
DEFINE rec t_cust
RETURN rec.*
END FUNCTION
FUNCTION func2( rec t_cust INOUT ) RETURNS ()
CALL func22(rec)
END FUNCTION
FUNCTION func22( rec t_cust INOUT ) RETURNS ()
END FUNCTION
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For more details, see Passing records by reference