Child Packages for Generic Packages

Requirements

• The child of a generic package must itself be generic


• A generic child must be instantiated
• A generic child is instantiated using the instance of the parent package

Example 1

• Let's create a child package that contains a function that returns the size of a stack.
• We've already seen the generic parent stack package and prettified


• Here is the child specification and prettified


• Here is a client and prettified


• Here is the child body prettified


• This generic child does not have any parameters.
• The generic child in the next example does have parameters.

Example 2

• Now let's create a child package with these operations
• function size(s: Stack) return Integer (as above)
• procedure print_stack(s: Stack) (for printing the stack)


• What is required to print a stack?


• Let's see:
• Child specification and pretty


• Client and pretty


• Child body and pretty