Oracle Package: Package specification:Global Variables
A magic value is a literal that has special significance in a system. These values might be type codes or validation limits. Your users will tell you that these magic values never change.
Having 25 line items in my profit-and-loss," one will say. "The name of the parent company," swears another, "will always be eBiztechnics.".In this case don't hard these into your program.
PACKAGE config_pkg
IS
cl_status CONSTANT VARCHAR2(1) := 'C';
op_status CONSTANT VARCHAR2(1) := 'O';
act_status CONSTANT VARCHAR2(1) := 'A';
inact_status CONSTANT VARCHAR2(1) := 'I';
min_diff CONSTANT NUMBER := 1;
max_diff CONSTANT NUMBER := 100;
e_date CONSTANT DATE := SYSDATE;
l_date CONSTANT DATE := ADD_MONTHS (SYSDATE, 120);
END config_pkg;
Using this package, my two IF statements above now become:
IF footing_difference
BETWEEN config_pkg.min_diff and config_pkg.max_diff
THEN
xyz;
END IF;
IF cust_status = config_pkg.cl_satus
THEN
abc;
END IF;
Notice that when you reference a package element you must use dot notation in the format package_name.object_name so the compiler can resolve the reference to the object's name. This is similar to prefacing a reference to a GLOBAL variable in Oracle Forms with the word GLOBAL, as in :GLOBAL.system_name.
If any of my magic values ever change, we need to modify only the assignment to the appropriate constant in the configuration package. we do not need to change a single program module
There is another motivation for writing a package without a body: . If you follow a top-down design process, you start with a general description of an application and gradually decompose into separate functional areas, programs, or individual statements. With the package structure you can immediately translate high-level refinements into code, while at the same time postponing a resolution of the actual implementation of that code.
