---
name: "Class::Adapter::Clear"
section: "3pm"
platform: "linux"
package: "libclass-adapter-perl"
version: "1.09-2"
release: "Debian 13 (Trixie)"
platforms: ["linux"]
url: "https://new.carta.tech/Class::Adapter::Clear"
---

# Class::Adapter::Clear(3pm)

A handy base Adapter class that makes no changes

## NAME

Class::Adapter::Clear - A handy base Adapter class that makes no changes

## VERSION

version 1.09

## SYNOPSIS

**Hello World with CGI.pm the normal way**

```
  # Load and create the CGI
  use CGI;
  $q = new CGI;

  # Create the page
  print $q->header,                    # HTTP Header
        $q->start_html('hello world'), # Start the page
        $q->h1('hello world'),         # Hello World!
        $q->end_html;                  # End the page
```

**Hello World with CGI.pm the Adapter'ed way**

```
  # Load and create the CGI
  use CGI;
  $q = new CGI;

  # Convert to an Adapter
  use Class::Adapter::Clear;
  $q = new Class::Adapter::Clear( $q );

  # Create the page
  print $q->header,                    # HTTP Header
        $q->start_html('hello world'), # Start the page
        $q->h1('hello world'),         # Hello World!
        $q->end_html;                  # End the page
```

**Creating a CGI Adapter class using Class::Adapter::Clear**

```
  package My::CGI;

  use base 'Class::Adapter::Clear';

  # Optional - Create the thing we are decorating auto-magically
  sub new {
      my $class = shift;

      # Create the object we are decorating
      my $query = CGI->new(@_);

      # Wrap it in the Adapter
      $class->SUPER::new($query);
  }

  # Decorate the h1 method to change what is created
  sub h1 {
        my $self = shift;
        my $str  = shift;

    # Do something before the real method call
    if ( defined $str and $str eq 'hello world' ) {
        $str = 'Hello World!';
    }

    $self->_OBJECT_->($str, @_);
  }
```

## DESCRIPTION

`"Class::Adapter::Clear"` provides the base class for creating one common type of Class::Adapter classes. For more power, move up to Class::Adapter::Builder.

On it's own `"Class::Adapter::Clear"` passes all methods through to the same method in the parent object with the same parameters, responds to `"->isa"` like the parent object, and responds to `"->can"` like the parent object.

It looks like a `"Duck"`, and it quacks like a `"Duck"`.

On this base, you simple implement whatever method you want to do something special to.

```
  # Different method, same parameters
  sub method1 {
      my $self = shift;
      $self->_OBJECT_->method2(@_); # Call a different method
  }

  # Same method, different parameters
  sub method1 {
      my $self = shift;
      $self->_OBJECT_->method1( lc($_[0]) ); # Lowercase the param
  }

  # Same method, same parameters, tweak the result
  sub method1 {
      my $self = shift;
      my $rv = $self->_OBJECT_->method1(@_);
      $rv =~ s/\n/<br>\n/g; # Add line-break HTML tags at each newline
      return $rv;
  }
```

As you can see, the advantage of this full-scale *Adapter* approach, compared to inheritance, or function wrapping (see Class::Hook), is that you have complete and utter freedom to do anything you might need to do, without stressing the Perl inheritance model or doing anything unusual or tricky with `"CODE"` references.

You may never need this much power. But when you need it, you **really** need it.

As an aside, Class::Adapter::Clear is implemented with the following Class::Adapter::Builder formula.

```
  use Class::Adapter::Builder
      ISA      => '_OBJECT_',
      AUTOLOAD => 1;
```

## METHODS

### new $object

As does the base Class::Adapter class, the default `"new"` constructor takes a single object as argument and creates a new object which holds the passed object.

Returns a new `"Class::Adapter::Clear"` object, or `"undef"` if you do not pass in an object.

## SEE ALSO

Class::Adapter, Class::Adapter::Builder

## SUPPORT

Bugs may be submitted through the RT bug tracker \<https://rt.cpan.org/Public/Dist/Display.html?Name=Class-Adapter\> (or bug-Class-Adapter@rt.cpan.org \<mailto:bug-Class-Adapter@rt.cpan.org\>).

## AUTHOR

Adam Kennedy \<adamk@cpan.org\>

## COPYRIGHT AND LICENSE

This software is copyright (c) 2005 by Adam Kennedy.

This is free software; you can redistribute it and/or modify it under the same terms as the Perl 5 programming language system itself.