perltoot 5.8.8

perltoot is Toms object-oriented tutorial for perl. Object-oriented programming is a big seller these days. Some managers would rather have objects than sliced bread. Why is that? Whats so special about an object? Just what is an object anyway? An object is nothing but a way of tucking away complex behaviours into a neat little easy-to-use bundle. (This is what professors call abstraction.) Smart people who have nothing to do but sit around for weeks on end figuring out really hard problems make these nifty objects that even regular people can use. (This is what professors call software reuse.) Users (well, programmers) can play with this little bundle all they want, but they arent to open it up and mess with the insides. Just like an expensive piece of hardware, the contract says that you void the warranty if you muck with the cover. So dont do that. The heart of objects is the class, a protected little private namespace full of data and functions. A class is a set of related routines that addresses some problem area. You can think of it as a user-defined type. The Perl package mechanism, also used for more traditional modules, is used for class modules as well. Objects "live" in a class, meaning that they belong to some package. More often than not, the class provides the user with little bundles. These bundles are objects. They know whose class they belong to, and how to behave. Users ask the class to do something, like "give me an object." Or they can ask one of these objects to do something. Asking a class to do something for you is calling a class method. Asking an object to do something for you is calling an object method. Asking either a class (usually) or an object (sometimes) to give you back an object is calling a constructor, which is just a kind of method. Thats all well and good, but how is an object different from any other Perl data type? Just what is an object really; that is, whats its fundamental type? The answer to the first question is easy. An object is different from any other data type in Perl in one and only one way: you may dereference it using not merely string or numeric subscripts as with simple arrays and hashes, but with named subroutine calls. In a word, with methods. The answer to the second question is that its a reference, and not just any reference, mind you, but one whose referent has been bless()ed into a particular class (read: package). What kind of reference? Well, the answer to that one is a bit less concrete. Thats because in Perl the designer of the class can employ any sort of reference theyd like as the underlying intrinsic data type. It could be a scalar, an array, or a hash reference. It could even be a code reference. But because of its inherent flexibility, an object is usually a hash reference..

Requirements:	No special requirements
Platforms:	Linux
Keyword:	Class,  Do Something,  Libraries,  Object,  Objects,  Perltoot,  Programming,  Reference,  To Do,  Type
Users rating:	0/10