Perl ABC

1. Perl
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2. Object Oriented
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3. "Monotype" and "Human type"

"Monotype" object and "Human type" object

In object-oriented programming, objects are not "things". There are two types of objects: "things" type objects and "people" type objects.

1. "Things" type object

A "thing" type object is an object that represents a "thing" . The following is this object, but it has title and price as attributes.

my $book = Book->new(title =>'a', price => 2300);

Such "things" type objects are constructors that set book properties such as titles and prices . You can think of a "thing" type object as something very close to a hash . Monotype objects represent structured data.

my $book = {title =>'a', price => 2300};

2. "Human" type object

A "human" type object is an object that represents "human" . Below are the objects that parse the file. It has encoding (circular coding method) and err_raise (raises an exception if parsing fails) as attributes.

After that, a method called parse that parses the file will be called.

my $file_parser = FileParser->new(encoding =>'utf8', err_raise => 1);
$file_parser->parse($file);

Such "human" objects often specify in the constructor the options used by subsequent methods . Think of a "human" object as something very close to a function .

my $opt = {encoding =>'utf8', err_raise => 1};
parse_file ($file, $opt);

3. Class design guidelines

1. First, be aware of whether you want to create a "thing" type object or a "human" type object.
2. If you want to represent data, create a "thing" typeclass
3. If you want to call a method with options, create a "human" typeclass
4. If convenience is superior, it may be a hybrid class in which the "thing" type is mixed with the "human" type.