Beginner's introduction to the Perl Module Template Toolkit. Part of a presentation given at Atlanta Perl Mongers February 2011.

1. Template Toolkit

3. Feed document through program

4. Output is as you wanted

7. Portability

8. Trainability

9. More extensive features

12. HTML::Template

13. HTML::Mason

14. HTML::Embperl

15. Apache::ASP

17. Usable through a number of web frameworks

20. cpan>install Template

22. Installed as part of the standard Catalyst installation.

23. Using Template Toolkit #! /usr/bin/perl use strict; use Template; my $tt = Template->new(); my $file = “webpage.tt”; my $vars = { person => 'Sam Spade', book => 'Maltese Falcon' }; $tt->process( $file, $vars ) || die $tt->error();

24. Passing Variables to TT Hashes and arrays should be passed as references: $arrayref = [ 1, 2, 3, 4 ]; $hashref = { foo => 1, bar => 2 }; This is also true within Catalyst

25. Simple example template Dear [%- customer -%], We are introducing five new products we want you to consider: [% product.0 %] [% product.1 %] [% product.2 %] [% product.3 %] [% product.4 %]

26. Pre and post chomp No chomp [% foo %] Pre chomp – removes before current line [%- foo %] Post chomp – removes on current line [% foo -%] Both pre and post chomped [%- foo -%] ^_^

27. Dots dereference components. [% myhash.3.component.7.subcomponent %]

28. TT provides virtual methods. In use, looks like Ruby [% string.length %] [% myhash.keys.sort %] [% hashlist.keys.sort.join(', ') %]

29. TT flow of control These teams have the following quarterbacks: [% FOREACH team IN league.keys.sort -%] [% NEXT UNLESS team.defined -%] [% team.name %]: [% team.qb %] [% IF team.owner -%] This team is owned by [% team.owner -%] [% ELSE -%] This team is owned by a committee. [% END -%] [% END -%]

31. WHILE

32. NEXT, LAST

33. IF, ELSIF, ELSE, UNLESS

34. SWITCH, CASE

35. Variables within TT [% foo = 7 %] [%# Is shorthand for %] [% SET foo = 7 %] [%# array example %] [% mylist = [1,2,3,4,5] %] [%# hash example %] [% name = { first = 'John' last = 'Dough' } %]

36. Comments within TT [% # comment to end of line # more commentary myname = 7 -%] [%# comment until terminating chars %] The space between the % and the # makes a difference.

37. Process and Include directives [%# These add stuff from external files to your document -%] [% PROCESS stuff %] [%# process acts like a source statement in shell. Any variables added have document level scope. %] [% INCLUDE morestuff %] [%# The include statement, by contrast, keeps those variables local to its own included file %]

38. Using PROCESS [% PROCESS commonheader %] My main web page content [% PROCESS ads %] [% PROCESS commonfooter %]

39. TAGS directive [% TAGS mason %] The <% location > party is <% opinion >. ~~~ [%# 2 args to TAGS = start and end directives %] [% TAGS { } %] ~~~ Or in code .. my $tt = Template->new({ START_TAG => quotemeta(''), END_TAG => quotemeta(''), });

41. Template->new({ WRAPPER => 'wrapper.tt' });

42. Similar functionality is provided by Catalyst.

44. http://www.paehl.com/open_source/?HTML_Tidy_for_Windows

45. META directive [%# Meta allows the inner template to pass information out to a wrapper. %] [% META title = 'This is a math equation' -%]

46. INTERPOLATE flag When set, bare Perl variables can be inserted into text. This is a math equation: $math This flag is off by default.

47. BLOCK directive Useful for simplifying chunks of code that can be included or processed later. [% BLOCK button %] Code for HTML button [% END %] TT has ways to build libraries of BLOCKs.

48. Exception Handling [% TRY %] [% USE DBI(mydb) %] [% CATCH %] Error:: [% error %] [% END %]

49. PERL directive Need to add EVAL_PERL => 1 to constructor to use. [% PERL %] for ( 1 .. 5 ) { print “Hello world!”; } [% END %]

50. PERL directive Template directives within the PERL block are evaluated before the PERL block is. So code like the below is legal. [% PERL %] print “Hello, [% name %] I [% verb %]!”; print “I must eat [% entree %] and [% side %].”; [% END %]

51. RAWPERL directive More efficient, but output restricted to appending to $output variable. Only for TT experts, in general. [% RAWPERL %] Stuff; $output .= “ more data”; [% END %]

52. FILTERS Filters transform data contained with the FILTER block. FILTER html makes text HTML safe <code> [% FILTER html %] Lots of C or shell here & this, >> and << that. [% END %] </code>

53. FILTERS II The | symbol is a shortcut for FILTER and can be used to do inline filtering. [% e = 2.718281828 ; e | format('%0.3f') %]

54. FILTER Examples 1. Convert text to PDF [% FILTER latex(“pdf”) %] Text here [% END %] 2. Add <br /> to all ends of lines [% FILTER html_line_break %] To be or not to be That is the question [% END %]

55. Plugins Implemented via the USE directive. [% USE date %] Today is [% date.format %]. [% calc = date.calc %] [% calc.Monday_of_week(27,2008).join('-') %] [% manip = date.manip %]

57. CGI

58. Datafile

59. Directory

60. DBI

61. Dumper

62. File

64. String

65. Table

66. URL

67. Wrap

68. XML::DOM

69. XML::RSS

70. XML::Style