PPI::Transform - Abstract base class for document transformation classes

       Adam Kennedy <adamk@cpan.org>

       Copyright 2001 - 2011 Adam Kennedy.

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

       The full text of the license can be found in the LICENSE file included with this module.

perl v5.40.1                                       2025-08-10                                PPI::Transform(3pm)

       "PPI::Transform" provides an API for the creation of classes and objects that modify or transform PPI
       documents.

new
         my $transform = PPI::Transform->new(
             param1 => 'value1',
             param2 => 'value2',
         );

       The "new" constructor creates a new object for your "PPI::Transform" subclass. A default constructor is
       provided for you which takes no params and creates a basic, empty, object.

       If you wish to have your transform constructor take params, these must be in the form of a list of
       key/value pairs.

       Returns a new "PPI::Transform"-compatible object, or returns "undef" on error.

   document
       The "document" method should be implemented by each subclass, and takes a single argument of a
       PPI::Document object, modifying it inplace as appropriate for the particular transform class.

       That's right, this method willnotclone and shouldnotclone the document object. If you do not want the
       original to be modified, you need to clone it yourself before passing it in.

       Returns the numbers of changes made to the document. If the transform is unable to track the quantity
       (including the situation where it cannot tell IF it made a change) it should return 1. Returns zero if no
       changes were made to the document, or "undef" if an error occurs.

       By default this error is likely to only mean that you passed in something that wasn't a PPI::Document,
       but may include additional errors depending on the subclass.

   apply
       The "apply" method is used to apply the transform to something. The argument must be a PPI::Document, or
       something which can be turned into one and then be written back to again.

       Currently, this list is limited to a "SCALAR" reference, although a handler registration process is
       available for you to add support for additional types of object should you wish (see the source for this
       module).

       Returns true if the transform was applied, false if there is an error in the transform process, or may
       die if there is a critical error in the apply handler.

   file
         # Read from one file and write to another
         $transform->file( 'Input.pm' => 'Output.pm' );

         # Change a file in place
         $transform->file( 'Change.pm' );

       The "file" method modifies a Perl document by filename. If passed a single parameter, it modifies the
       file in-place. If provided a second parameter, it will attempt to save the modified file to the
       alternative filename.

       Returns true on success, or "undef" on error.

       PPI::Transform - Abstract base class for document transformation classes

       See the support section in the main module.