Intermediate Perl

14.1. UNIVERSAL Methods As we define classes, we create inheritance hierarchies through the global @ISA variables in each package. To search for a method, Perl wanders through the @ISA TRee until it finds a match or fails. After the sear...

14.2. Testing Our Objects for Good Behavior Besides providing a place for us to put universally available methods, the UNIVERSAL package comes preloaded with two very useful utility methods: isa and can. Because UNIVERSAL defines these me...

14.3. AUTOLOAD as a Last Resort After Perl searches the inheritance tree and UNIVERSAL for a method, it doesn't just stop there if the search is unsuccessful. Perl repeats the search through the very same hierarchy (including UNIVER...

14.4. Using AUTOLOAD for Accessors Chapter 12 showed how to create color and set_color to get and set the color of an animal. If we had 20 attributes instead of 1 or 2, the code would be painfully repetitive. However, using an AUTOLOAD metho...

14.5. Creating Getters and Setters More Easily If all that coding for creating accessors using AUTOLOAD looks messy, rest assured that we really don't need to tackle it, because there's a CPAN module that does it a bit more directly...

14.6. Multiple Inheritance How does Perl wander through the @ISA TRee? The answer may be simple or complex. If we don't have multiple inheritance (that is, if no @ISA has more than one element), it is simple: Perl simply goes from one ...

14.7. Exercises You can find the answers to these exercises in "Answers for Chapter 14" in the Appendix. 14.7.1. Exercise 1 [20 min] Write a module named MyDate that has an AUTOLOAD method that handles the calls to the methods named day, month...