1PPI::Transform(3) User Contributed Perl Documentation PPI::Transform(3)
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6 PPI::Transform - Abstract base class for document transformation
7 classes
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10 "PPI::Transform" provides an API for the creation of classes and
11 objects that modify or transform PPI documents.
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14 new
15 my $transform = PPI::Transform->new(
16 param1 => 'value1',
17 param2 => 'value2',
18 );
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20 The "new" constructor creates a new object for your "PPI::Transform"
21 subclass. A default constructor is provided for you which takes no
22 params and creates a basic, empty, object.
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24 If you wish to have your transform constructor take params, these must
25 be in the form of a list of key/value pairs.
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27 Returns a new "PPI::Transform"-compatible object, or returns "undef" on
28 error.
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30 document
31 The "document" method should be implemented by each subclass, and takes
32 a single argument of a PPI::Document object, modifying it in place as
33 appropriate for the particular transform class.
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35 That's right, this method will not clone and should not clone the
36 document object. If you do not want the original to be modified, you
37 need to clone it yourself before passing it in.
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39 Returns the numbers of changes made to the document. If the transform
40 is unable to track the quantity (including the situation where it
41 cannot tell IF it made a change) it should return 1. Returns zero if no
42 changes were made to the document, or "undef" if an error occurs.
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44 By default this error is likely to only mean that you passed in
45 something that wasn't a PPI::Document, but may include additional
46 errors depending on the subclass.
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48 apply
49 The "apply" method is used to apply the transform to something. The
50 argument must be a PPI::Document, or something which can be turned into
51 one and then be written back to again.
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53 Currently, this list is limited to a "SCALAR" reference, although a
54 handler registration process is available for you to add support for
55 additional types of object should you wish (see the source for this
56 module).
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58 Returns true if the transform was applied, false if there is an error
59 in the transform process, or may die if there is a critical error in
60 the apply handler.
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62 file
63 # Read from one file and write to another
64 $transform->file( 'Input.pm' => 'Output.pm' );
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66 # Change a file in place
67 $transform->file( 'Change.pm' );
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69 The "file" method modifies a Perl document by filename. If passed a
70 single parameter, it modifies the file in-place. If provided a second
71 parameter, it will attempt to save the modified file to the alternative
72 filename.
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74 Returns true on success, or "undef" on error.
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77 See the support section in the main module.
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80 Adam Kennedy <adamk@cpan.org>
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83 Copyright 2001 - 2011 Adam Kennedy.
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85 This program is free software; you can redistribute it and/or modify it
86 under the same terms as Perl itself.
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88 The full text of the license can be found in the LICENSE file included
89 with this module.
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93perl v5.28.1 2017-06-22 PPI::Transform(3)