This chapter discusses the concept of packages in Advanced Server. A package is a named collection of functions, procedures, variables, cursors, user-defined record types, and records that are referenced using a common qualifier – the package identifier. Packages have the following characteristics:
- Packages provide a convenient means of organizing the functions and procedures that perform a related purpose. Permission to use the package functions and procedures is dependent upon one privilege granted to the entire package. All of the package programs must be referenced with a common name.
- Certain functions, procedures, variables, types, etc. in the package can be declared as public. Public entities are visible and can be referenced by other programs that are given
EXECUTEprivilege on the package. For public functions and procedures, only their signatures are visible - the program names, parameters if any, and return types of functions. The SPL code of these functions and procedures is not accessible to others, therefore applications that utilize a package are dependent only upon the information available in the signature – not in the procedural logic itself.
- Other functions, procedures, variables, types, etc. in the package can be declared as private. Private entities can be referenced and used by function and procedures within the package, but not by other external applications. Private entities are for use only by programs within the package.
- Function and procedure names can be overloaded within a package. One or more functions/procedures can be defined with the same name, but with different signatures. This provides the capability to create identically named programs that perform the same job, but on different types of input.
package_components creating_packages referencing_a_package using_packages_with_user_defined_types dropping_a_package