1. Copyright 2001, ActiveState

2. Using perl with Zope Andy McKay, ActiveState Python 9 Conference

3. Copyright 2001, ActiveState Agenda About using Perl with Zope Why Perl with Zope? Example of use –Perl Restricted methods –Perl Unrestricted methods –Perl DBI Perl from Python Internals

4. Copyright 2001, ActiveState Perl with Zope Created by ActiveState for Digital Creations. Developed done by Gisle Aas. Goal: "To provide an alternative to Python for scripting Zope in the same process." Currently in beta?

5. Copyright 2001, ActiveState Perl with Zope does not… Mean a rewriting of Zope Allow the creation of a Perl only product Zope speaks lots of different things (FTP, SOAP, WebDAV etc.)… and now Perl

6. Copyright 2001, ActiveState Perl with Zope does allow… Creation of Perl Scripts through the web –Perl Script –Similar to Python Script Creation of Perl External Methods –Perl Script (Unrestricted) –Similar to External Method Using Perl within Python

7. Copyright 2001, ActiveState Why use perl with Zope? Code reuse –Access to legacy scripts and modules –Most things have already been done in perl –Perl Cookbook, Programming Perl etc… Large number of Perl developers –Community and knowledge –Perl is on Linux and most people use Linux What OS do you primarily run Zope on? –Linux 43.09% –Windows NT/2000 25.97% –Windows 9x 6.91% –Unix 6.91% 362 users polled, from www.ZopeZen.org.

8. Copyright 2001, ActiveState Why use perl with Zope? CPAN –CPAN: Comprehensive Perl Archive Network –PPM: Perl Package Manager

9. Copyright 2001, ActiveState Why use perl with Zope? CPAN –CPAN: Comprehensive Perl Archive Network –PPM: Perl Package Manager – CPAN: 1,964 modules – Zope.org: 296 products

10. Copyright 2001, ActiveState Technical Overview Two parts: –Pyperl Python Perl integration, not Zope specific. Current version 1.0 – Zoperl Depends on pyperl. Zope specific, platform independent code. –Script Perl (restricted) –Script Perl (unrestricted) –Z DBI Database Connection Current version beta 0.5

11. Copyright 2001, ActiveState Script Perl (restricted) Zope object: Script (Perl) –Edited through the web –Access to most of the Perl core –Can’t use modules –Runs in strict Similar in idea to Script (Python)

12. Copyright 2001, ActiveState Example, Object listing (DTML) Get a listing of Zope objects using objectIds() in a container In DTML… Example: List

13. Copyright 2001, ActiveState Example, Object listing (Python) In Script Python… –context is bound by default in Python methods –can use print / printed shortcut for item in context.objectIds(): print item return printed Example: ListPY

14. Copyright 2001, ActiveState In Script Perl… –self is declared as an argument Example, Object listing (Perl) my @res; for ($self->objectIds()) { push(@res, $_); } return join("\n", @res); Example: ListPL

15. Copyright 2001, ActiveState Gotchas Can’t get an item (such as a folder) the same as python –context.folder.objectIds() works. –$self->folder->objectIds() doesn’t. Zope Error Error Type: AttributeError Error Value: __call__ Note: Perl errors are raised as Python errors…

16. Copyright 2001, ActiveState Python::getitem Use Python::getitem(..) –Arguments: object, subobject id my @res; my $folder = Python::getitem($self, ‘Control_Panel'); for ( (Python::getitem($folder, 'Products'))->objectIds() ) { if ($_ =~ m/perl/i) { push(@res, $_); } return join("\n", @res) Example: ListProducts

17. Copyright 2001, ActiveState The good, the bad and the ugly Good –Regex’s, transliterations etc are available Bad – Regex’s, transliterations etc are available – No loop limit – No bindings and other Python Script features – getitem Ugly – Through the web editing – “Guilty as charged. Perl is happily ugly, and happily derivative”, Larry Wall

18. Copyright 2001, ActiveState Script Perl, unrestricted Zope object: Script (Perl, unrestricted) –Edited on file system –Access to all of the Perl core –Can use modules –Can choose “strictness” Similar in idea to External Method

19. Copyright 2001, ActiveState Example (Calendar) A web based calendar that uses some interesting CPAN modules… Elements: – CPAN Modules – Actual perl module for finding monthly and daily information – Scripts (Perl, unrestricted) to call from DTML – DTML Method to display calendar

20. Copyright 2001, ActiveState Calendar: Perl Setup Installing CPAN modules: –Installed from CPAN or via PPM File location: /Extensions/ZopeExt/Calendar.pm #! /usr/bin/perl -w use strict; package ZopeExt::Calendar; # import modules use Date::Calc; use Date::Manip; … Example: Calendar.pm

21. Copyright 2001, ActiveState Calendar: Perl Scripts sub Month { my ($year, $month, $day) = split('/', $_[0]); if (!Date::Calc::check_date ($year, $month, $day)) { Python::raise('DateError', “Date not valid"); } my %hash; $hash{'month_name'} = Date::Calc::Month_to_Text($month); … return \%hash; } Note: Having "month" as an argument ensures I will be passed something. Example: Calendar.pm

22. Copyright 2001, ActiveState Calendar: Perl Scripts (Alt) sub Day { my ($year, $month, $day); my $self = shift; my %request = %{$self->{'REQUEST'} }; if (exists $request{'day'}) { ($year, $month, $day) = split('/', $request{'day'}); if (!Date::Calc::check_date ($year, $month, $day)) { Python::raise('DateError', 'Date not valid'); } } else { Python::raise('DateError', 'No day given'); } Note: Having "self" as an argument ensures I will be passed "self", so I can call REQUEST etc… Example: Calendar.pm

23. Copyright 2001, ActiveState Calendar: Access Requires hack to AccessControl to allow hashes and arrays to be returned without security machinery complaining. –from Chris McDonough Calendar: Perl Scripts import Record try: import perl perlhash = perl.get_ref("%") except: perlhash = {} ContainerAssertions ={ … type(perlhash): 1, … }

24. Copyright 2001, ActiveState Calendar: Scripts Create objects to be called. Eg: –Id: CalendarMonthPM –Function name: Month –Function arguments: month –Perl module: ZopeExt::Calendar Example: CalendarMonthPM

25. Copyright 2001, ActiveState Calendar: DTML DTML to show calendar Returning a hash reference, uses mapping. For array use Example: CalendarExample

26. Copyright 2001, ActiveState Calendar: End Result Example: CalendarExample

27. Copyright 2001, ActiveState Gotchas Use getattr and setattr to modify things such as REQUEST/ Returning complex data structures can be tricky to DTML.

28. Copyright 2001, ActiveState ZDBI DA One other product, ZDBI_DA Perl DBI has access to most databases, can go where Python can’t… A Python object that forwards requests to Perl DBI. Roughly 30% performance hit over native drivers

29. Copyright 2001, ActiveState Using Perl in Python As of pyperl-1.0, released Thursday... Added in a wrapping around Perl objects so they can be called from Python. –Currently works best on Perl objects Syntax: from perlmod import Perl think of it as a dot (.) instead of two colons in an object…

30. Copyright 2001, ActiveState Using Perl in Python Python 1.5.2 (#0, Jul 30 1999, 09:52:18) [MSC 32 bit (Intel)] on win32 Copyright 1991-1995 Stichting Mathematisch Centrum, Amsterdam >>> from perlmod import Perl >>> import time >>> s = Perl.Date.Tolkien.Shire(time.time()) >>> print s.on_date() Highday Rethe 11 7465 Gollum visits Shelob, 1419. …

31. Copyright 2001, ActiveState Using Perl in a Zope Product FSCounter, simple Zope product to provide a hit counter. –File system used to avoid Data.fs bloat Problem: –No simple and easy cross platform locking mechanism in Python –fcntl is Unix only Solution: –File::Counter from CPAN

32. Copyright 2001, ActiveState Example: FSCounter from perlmod import Perl # perl … def write(self): ''' increment file, perl ''' p = Perl.File.CounterFile(self._filename()) return p.inc() def read(self): ''' read file, perl ''' p = Perl.File.CounterFile(self._filename()) return p.value() Example: counter, footer

33. Copyright 2001, ActiveState Internals Full API not of interest here, whole talk all of its own. Discussed by Gisle Aas in the paper. Of interest: –Exceptions –Complex data types –Threading

34. Copyright 2001, ActiveState Exceptions Can raise an error by: –Python::raise($type, $value) The Python::Err::-functions also return the standard python exception type objects if called without arguments. –Python::raise(Python::Err::IndexError, "out of range")

35. Copyright 2001, ActiveState Complex data types PyPerl does conversion of simple data type (strings, int etc) Perl ref object is a reference to a python object that encapsulates a perl reference. Python 1.5.2 (#0, Jul 30 1999, 09:52:18) [MSC 32 bit (Intel)] on win32 Copyright 1991-1995 Stichting Mathematisch Centrum, Amsterdam >>> import perl >>> inc = perl.get_ref("@INC") >>> inc >>> len(inc) 3

36. Copyright 2001, ActiveState Threading Perl is multi-threaded when used with Python. A Perl interpreter is opened up for each thread. It is released when Zope releases its thread. Perl references cannot be passed between Perl threads. Don’t try and pickle a Perl reference.

37. Copyright 2001, ActiveState Future PyPerl the python-perl part of Zope Perl as part of PPM, meaning very easy install. PyPerl finalised. ZoPerl the zope-perl part of Zope Perl as part of the Zope core? Currently in beta, be finished RSN.

38. Copyright 2001, ActiveState More information Project homepage: www.zope.org/Wikis/zope-perl/FrontPage Zope Perl available from: www.ActiveState.com/download/Zope-Perl/ Examples, plus this talk at: www.zope.org/Members/andym Mailing list: Zope-Perl@Zope.org