NAME
Perl::Signature - Generate functional signatures for Perl source code
DESCRIPTION
In early beta, PPI introduced the concept of "Document Normalization"
into the core. It had previously only been implemented "behind the
scenes" as part of Perl::Compare.
Unfortunately, there isn't a whole lot of things you can do with a
PPI::Document::Normalized object. It's a giant twisty mass of objects
and perl structure, and not very practical for long term storage.
Perl::Signature implements the idea of a "functional signature" for Perl
documents, implemented in a similar way to Object::Signature.
The normalized document is serialized to a string with Storable, then
this string is converted into a MD5 hash, producing a single short
string which represents the functionality of the Perl document.
This signature can then be stored and transfered easily, and at any
later point the signature can be regenerated for the file to ensure that
it has not changed (functionally).
Not Stable Across Upgrades
Perl::Signature is relatively sensitive to change.
Primarily, this is because PPI::Normal is biased towards false negative
comparison. (Avoiding false "these are the same" by accepting a number
of false "these are not the same" results).
In addition, the serialization of Storable is not assured to use
identical file formats across versions.
In short, you should assume that a signature is valid at best for only
as long as the PPI and Storable versions are the same, and at worst only
for the current process.
METHODS
PPI::Signature provides two sets of methods. A set of
file_signature $filename
The "file_signature" static method takes a filename and produces a
signature for the file.
Returns a 32 character hexidecimal MD5 signature, or "undef" on error.
source_signature $content | \$content
The "source_signature" static method generates a signature for any
arbitrary Perl source code, which can be passed as either a raw string,
or a reference to a SCALAR containing the code.
Returns a 32 character hexidecimal MD5 signature, or "undef" on error.
document_signature $Document
The "document_signature" method takes a PPI::Document object and
generates a signature for it.
Returns a 32 character hexidecimal MD5 signature, or "undef" on error.
new $file
As well as static methods for generatic signatures, Perl::Signature also
provides a simple way to create signature objects for a particular file.
This makes it relatively easy to see if a file has changed
The "new" constructor takes as argument the name of a file, and creates
an object that remembers current signature of the file.
file
The "file" accessor returns the name of the file that a Perl::Signature
object is set to.
current
The "current" method returns the current signature for the file.
Returns a 32 character hexidecimal MD5 signature, or "undef" on error.
original
The "original" accessor returns the original signature at the time of
the creation of the object.
changed
The "changed" method checks to see if the signature has changed since
the object was created.
Returns true if the file has been (functionally) changed, false if not,
or "undef" on error.
unchanged
The "unchanged" method checks to ensure that the signature has not
changed since the object was created.
Returns true if the file is (functionally) unchanged, false if it has
changed, or "undef" on error.
SUPPORT
All bugs should be filed via the CPAN bug tracker at
<
http://rt.cpan.org/NoAuth/ReportBug.html?Queue=Perl-Signature>
For other issues, or commercial enhancement or support, contact the
author.
AUTHORS
Adam Kennedy <
[email protected]>
SEE ALSO
<
http://ali.as/>, PPI
COPYRIGHT
Copyright 2004 - 2008 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.
