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Diffstat (limited to 'pod/perlboot.pod')
| -rw-r--r-- | pod/perlboot.pod | 24 |
1 files changed, 18 insertions, 6 deletions
diff --git a/pod/perlboot.pod b/pod/perlboot.pod index bab365609e..b549f45e49 100644 --- a/pod/perlboot.pod +++ b/pod/perlboot.pod @@ -7,7 +7,7 @@ perlboot - Beginner's Object-Oriented Tutorial If you're not familiar with objects from other languages, some of the other Perl object documentation may be a little daunting, such as L<perlobj>, a basic reference in using objects, and L<perltoot>, which -introduces readers to the pecularities of Perl's object system in a +introduces readers to the peculiarities of Perl's object system in a tutorial way. So, let's take a different approach, presuming no prior object @@ -139,8 +139,8 @@ attempts to invoke subroutine C<Class::method> as: (If the subroutine can't be found, "inheritance" kicks in, but we'll get to that later.) This means that we get the class name as the -first parameter. So we can rewrite the C<Sheep> speaking subroutine -as: +first parameter (the only parameter, if no arguments are given). So +we can rewrite the C<Sheep> speaking subroutine as: sub Sheep::speak { my $class = shift; @@ -245,14 +245,15 @@ inheritance. When we turn on C<use strict>, we'll get complaints on C<@ISA>, since it's not a variable containing an explicit package name, nor is it a -lexical ("my") variable. We can't make it a lexical variable though, +lexical ("my") variable. We can't make it a lexical variable though +(it has to belong to the package to be found by the inheritance mechanism), so there's a couple of straightforward ways to handle that. The easiest is to just spell the package name out: @Cow::ISA = qw(Animal); -Or allow it as an implictly named package variable: +Or allow it as an implicitly named package variable: package Cow; use vars qw(@ISA); @@ -490,7 +491,7 @@ If Horse::sound had not been found, we'd be wandering up the C<@Horse::ISA> list to try to find the method in one of the superclasses, just as for a class method. The only difference between a class method and an instance method is whether the first parameter -is a instance (a blessed reference) or a class name (a string). +is an instance (a blessed reference) or a class name (a string). =head2 Accessing the instance data @@ -552,6 +553,17 @@ C<Horse::named> are C<Horse> and C<Mr. Ed>. The C<bless> operator not only blesses C<$name>, it also returns the reference to C<$name>, so that's fine as a return value. And that's how to build a horse. +We've called the constructor C<named> here, so that it quickly denotes +the constructor's argument as the name for this particular C<Horse>. +You can use different constructors with different names for different +ways of "giving birth" to the object (like maybe recording its +pedigree or date of birth). However, you'll find that most people +coming to Perl from more limited languages use a single constructor +named C<new>, with various ways of interpreting the arguments to +C<new>. Either style is fine, as long as you document your particular +way of giving birth to an object. (And you I<were> going to do that, +right?) + =head2 Inheriting the constructor But was there anything specific to C<Horse> in that method? No. Therefore, |