RPG Cafe: Fall 2020: New BIFs, FOREACH opcode

Content

New opcode FOR-EACH, and new built-in functions %RANGE and %LIST

• %RANGE: You can check whether a value is in the range of two other values by using the %RANGE built-in function.
• %LIST: You can create a temporary array by using the %LIST built-in function.
• 'IN' operator: You can check whether a value is "in" a range of values or in an array or %LIST.
• FOR-EACH opcode: You can iterate over an array or %LIST using the FOR-EACH opcodes. The FOR-EACH opcode begins a structured group that ends with the ENDFOR opcode.

Details

%RANGE

In this example, the IF statement is checking whether the current date is between the minimum and maximum registration dates.

Using x IN %RANGE(y : z) is the same as x >= y AND x <= z.

          IF %DATE() IN %RANGE(min_register_date : max_register_date);
             processRegistration (); // The date is in range
          IF;

%LIST

In this example, %LIST is used to create a temporary array to assign values to the names array.

          DCL-S names VARCHAR(20) DIM(3);

          names = %LIST('Mary' : 'Jack' : 'Alice');

IN operator

In this example, the 'IN' operator is used to check whether cust_city is equal to one of the values in the sale_cities array. %SUBARR is used to limit the number of elements that are checked.

Then, the 'IN' operator is used to check whether the cust_status is one of the values in the %LIST array.

          DCL-S sale_cities VARCHAR(20) DIM(10);
          DCL-S num_sale_cities INT(10);

          IF city IN %SUBARR(sale_cities : 1 : num_sale_cities);
             IF cust_status IN %LIST(STATUS_PREFERRED : STATUS_GOLD);
                subtract_discount (); // This customer gets a discount

FOR-EACH opcode

In this example, the FOR-EACH opcode is used to iterate over the values in the %LIST array.

Then, the FOR-EACH opcode is used to iterate over the elements in the errors array. %SUBARR is used to limit the number of elements that are processed.

          DCL-DS error LIKEDS(error_t);
          DCL-DS errors LIKEDS(error_t) DIM(100);
          DCL-S num_errors INT(10);
          DCL-S error_type INT(10);
          DCL-S filename VARCHAR(21);
          DCL-F logfile EXTDESC('LOGFILE_T') EXTNAME(filename);

          FOR-EACH filename IN %LIST('CUR_ERRORS' : 'ALL_ERRORS');
             OPEN logfile;
             FOR-EACH error IN %SUBARR(errors : 1 : num_errors);
                log_error_message (error);
             ENDFOR;
          ENDFOR;

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