1 package Template::Simple;
7 use Scalar::Util qw( reftype ) ;
12 our $VERSION = '0.03';
17 post_delim => qr/%\]/,
21 include_paths => [ qw( templates ) ],
26 my( $class, %opts ) = @_ ;
28 my $self = bless {}, $class ;
30 # get all the options or defaults into the object
32 while( my( $name, $default ) = each %opt_defaults ) {
34 $self->{$name} = defined( $opts{$name} ) ?
35 $opts{$name} : $default ;
38 # make up the regexes to parse the markup from templates
40 # this matches scalar markups and grabs the name
42 $self->{scalar_re} = qr{
44 \s* # optional leading whitespace
45 (\w+?) # grab scalar name
46 \s* # optional trailing whitespace
48 }xi ; # case insensitive
50 #print "RE <$self->{scalar_re}>\n" ;
52 # this grabs the body of a chunk in either greedy or non-greedy modes
54 my $chunk_body = $self->{greedy_chunk} ? qr/.+/s : qr/.+?/s ;
56 # this matches a marked chunk and grabs its name and text body
58 $self->{chunk_re} = qr{
60 \s* # optional leading whitespace
61 START # required START token
62 \s+ # required whitespace
63 (\w+?) # grab the chunk name
64 \s* # optional trailing whitespace
66 ($chunk_body) # grab the chunk body
68 \s* # optional leading whitespace
69 END # required END token
70 \s+ # required whitespace
71 \1 # match the grabbed chunk name
72 \s* # optional trailing whitespace
74 }xi ; # case insensitive
76 #print "RE <$self->{chunk_re}>\n" ;
78 # this matches a include markup and grabs its template name
80 $self->{include_re} = qr{
82 \s* # optional leading whitespace
83 INCLUDE # required INCLUDE token
84 \s+ # required whitespace
85 (\w+?) # grab the included template name
86 \s* # optional trailing whitespace
88 }xi ; # case insensitive
90 # load in any templates
92 $self->add_templates( $opts{templates} ) ;
99 my( $self, $template_name ) = @_ ;
101 my $tmpl_ref = eval {
102 $self->_get_template( $template_name ) ;
105 croak "Template::Simple $@" if $@ ;
107 # compile a copy of the template as it will be destroyed
109 my $code_body = $self->_compile_chunk( '', "${$tmpl_ref}", "\t" ) ;
111 $self->{source} = <<CODE ;
125 $self->{source_cache}{$template_name} = $self->{source} ;
126 print $self->{source} ;
128 my $code_ref = eval $self->{source} ;
132 $self->{compiled_cache}{$template_name} = $code_ref ;
138 my( $self, $chunk_name, $template, $indent ) = @_ ;
140 return '' unless length $template ;
146 # loop all nested chunks and the text separating them
148 while( $template =~ m{$self->{chunk_re}}g ) {
150 # grab the pre-chunk text and compile it for scalars and save all of its parts
152 push @parts, $self->_compile_scalars(
153 substr( $template, 0, $-[0] ) ) ;
155 # compile the nested chunk and save its parts
157 push @parts, $self->_compile_chunk( $1, $2, $indent ) ;
159 # chop off the pre-chunk and chunk
161 substr( $template, 0, $+[0], '' ) ;
164 # compile trailing text for scalars and save all of its parts
166 push @parts, $self->_compile_scalars( $template ) ;
168 # generate the code for this chunk
170 # start it with a do{} block open
172 my $code = "do {\n$indent" ;
174 # generate a lookup in data for this chunk name (unless it is the top
175 # level). this descends down the data tree during rendering
177 $code .= <<CODE . $indent if $chunk_name ;
178 my \$data = \$data->{$chunk_name} ;
181 # now generate the code to output all the parts of this chunk. they
182 # are all concatentated by the . operator
184 $code .= join( "\n$indent.\n$indent", @parts ) ;
186 # now we close the do block
189 $code .= "\n$indent}" ;
194 sub _compile_scalars {
196 my( $self, $template ) = @_ ;
198 # if the template is empty return no parts
200 return unless length $template ;
204 while( $template =~ m{$self->{scalar_re}}g ) {
206 # keep the text before the scalar markup and the code to access the scalar
209 dump_text( substr( $template, 0, $-[0] ) ),
212 substr( $template, 0, $+[0], '' ) ;
215 # keep any trailing text part
217 push @parts, dump_text( $template ) ;
228 return unless length $text ;
230 local( $Data::Dumper::Useqq ) = 1 ;
232 my $dumped = Dumper $text ;
234 $dumped =~ s/^[^"]+// ;
235 $dumped =~ s/;\n$// ;
242 my( $self, $template_name, $data ) = @_ ;
244 # render with cached code if we precompiled this template
246 if ( my $compiled = $self->{compiled_cache}{$template_name} ) {
248 return $compiled->($data) ;
251 # TODO: look for template by name
253 my $template = eval{ $self->_get_template($1) } ;
255 print "GOT [$template]\n" ;
257 # force the template into a ref
259 my $tmpl_ref = ref $template eq 'SCALAR' ? $template : \$template ;
261 my $rendered = $self->_render_includes( $tmpl_ref ) ;
263 #print "INC EXP <$rendered>\n" ;
266 $self->_render_chunk( $rendered, $data ) ;
269 croak "Template::Simple $@" if $@ ;
274 sub _render_includes {
276 my( $self, $tmpl_ref ) = @_ ;
278 # make a copy of the initial template so we can render it.
280 my $rendered = ${$tmpl_ref} ;
282 # loop until we can render no more include markups
285 s{$self->{include_re}}
286 { ${ $self->_get_template($1) }
294 HASH => \&_render_hash,
295 ARRAY => \&_render_array,
296 CODE => \&_render_code,
297 # if no ref then data is a scalar so replace the template with just the data
298 '' => sub { \$_[2] },
304 my( $self, $tmpl_ref, $data ) = @_ ;
306 #print "T ref [$tmpl_ref] [$$tmpl_ref]\n" ;
307 #print "CHUNK ref [$tmpl_ref] TMPL\n<$$tmpl_ref>\n" ;
309 #print Dumper $data ;
311 return \'' unless defined $data ;
313 # now render this chunk based on the type of data
315 my $renderer = $renderers{reftype $data || ''} ;
317 #print "EXP $renderer\nREF ", reftype $data, "\n" ;
319 die "unknown template data type '$data'\n" unless defined $renderer ;
321 return $self->$renderer( $tmpl_ref, $data ) ;
326 my( $self, $tmpl_ref, $href ) = @_ ;
328 return $tmpl_ref unless keys %{$href} ;
330 # we need a local copy of the template to render
332 my $rendered = ${$tmpl_ref} ;
335 # recursively render all top level chunks in this chunk
337 $rendered =~ s{$self->{chunk_re}}
339 # print "CHUNK $1\nBODY\n----\n<$2>\n\n------\n" ;
340 print "CHUNK $1\nBODY\n----\n<$2>\n\n------\n" ;
341 print "pre CHUNK [$`]\n" ;
342 ${ $self->_render_chunk( \"$2", $href->{$1} ) }
347 #print "HREF: ", Dumper $href ;
349 $rendered =~ s{$self->{scalar_re}}
351 # print "SCALAR $1 VAL $href->{$1}\n" ;
352 defined $href->{$1} ? $href->{$1} : ''
355 #print "HASH REND3\n<$rendered>\n" ;
362 my( $self, $tmpl_ref, $aref ) = @_ ;
364 # render this $tmpl_ref for each element of the aref and join them
368 #print "AREF: ", Dumper $aref ;
370 $rendered .= ${$self->_render_chunk( $tmpl_ref, $_ )} for @{$aref} ;
377 my( $self, $tmpl_ref, $cref ) = @_ ;
379 my $rendered = $cref->( $tmpl_ref ) ;
381 die <<DIE if ref $rendered ne 'SCALAR' ;
382 data callback to code didn't return a scalar or scalar reference
390 my( $self, $tmpls ) = @_ ;
392 #print Dumper $tmpls ;
393 return unless defined $tmpls ;
395 ref $tmpls eq 'HASH' or croak "templates argument is not a hash ref" ;
397 # copy all the templates from the arg hash and force the values to be
400 @{ $self->{tmpl_cache}}{ keys %{$tmpls} } =
401 map ref $_ eq 'SCALAR' ? \"${$_}" : \"$_", values %{$tmpls} ;
403 #print Dumper $self->{tmpl_cache} ;
408 sub delete_templates {
410 my( $self, @names ) = @_ ;
412 # delete all the cached stuff or just the names passed in
414 @names = keys %{$self->{tmpl_cache}} unless @names ;
416 # clear out all the caches
417 # TODO: reorg these into a hash per name
419 delete @{$self->{tmpl_cache}}{ @names } ;
420 delete @{$self->{compiled_cache}}{ @names } ;
421 delete @{$self->{source_cache}}{ @names } ;
423 # also remove where we found it to force a fresh search
425 delete @{$self->{template_paths}}{ @names } ;
432 my( $self, $tmpl_name ) = @_ ;
434 #print "INC $tmpl_name\n" ;
436 my $tmpls = $self->{tmpl_cache} ;
438 # get the template from the cache and send it back if it was found there
440 my $template = $tmpls->{ $tmpl_name } ;
441 return $template if $template ;
443 # not found, so find, slurp in and cache the template
445 $template = $self->_find_template( $tmpl_name ) ;
446 $tmpls->{ $tmpl_name } = $template ;
453 my( $self, $tmpl_name ) = @_ ;
455 foreach my $dir ( @{$self->{include_paths}} ) {
457 my $tmpl_path = "$dir/$tmpl_name.tmpl" ;
459 #print "PATH: $tmpl_path\n" ;
460 next unless -r $tmpl_path ;
462 # cache the path to this template
464 $self->{template_paths}{$tmpl_name} = $tmpl_path ;
466 # slurp in the template file and return it as a scalar ref
468 return scalar read_file( $tmpl_path, scalar_ref => 1 ) ;
472 can't find template '$tmpl_name' in '@{$self->{include_paths}}'
477 1; # End of Template::Simple
483 Template::Simple - A simple and fast template module
491 use Template::Simple;
493 my $tmpl = Template::Simple->new();
495 my $template = <<TMPL ;
498 [%first%] - [%second%]
505 date => 'Jan 1, 2008',
506 author => 'Me, myself and I',
510 first => 'row 1 value 1',
511 second => 'row 1 value 2',
514 first => 'row 2 value 1',
515 second => 'row 2 value 2',
519 modified => 'Aug 31, 2006',
523 my $rendered = $tmpl->render( $template, $data ) ;
527 Template::Simple has these goals:
531 =item * Support most common template operations
533 It can recursively include other templates, replace tokens (scalars),
534 recursively render nested chunks of text and render lists. By using
535 simple idioms you can get conditional renderings.
537 =item * Complete isolation of template from program code
539 This is very important as template design can be done by different
540 people than the program logic. It is rare that one person is well
541 skilled in both template design and also programming.
543 =item * Very simple template markup (only 4 markups)
545 The only markups are C<INCLUDE>, C<START>, C<END> and C<token>. See
548 =item * Easy to follow rendering rules
550 Rendering of templates and chunks is driven from a data tree. The type
551 of the data element used in an rendering controls how the rendering
552 happens. The data element can be a scalar or scalar reference or an
553 array, hash or code reference.
555 =item * Efficient template rendering
557 Rendering is very simple and uses Perl's regular expressions
558 efficiently. Because the markup is so simple less processing is needed
559 than many other templaters. Precompiling templates is not supported
560 yet but that optimization is on the TODO list.
562 =item * Easy user extensions
564 User code can be called during an rendering so you can do custom
565 renderings and plugins. Closures can be used so the code can have its
566 own private data for use in rendering its template chunk.
572 You create a Template::Simple by calling the class method new:
574 my $tmpl = Template::Simple->new() ;
576 All the arguments to C<new()> are key/value options that change how
577 the object will do renderings.
583 This option sets the string or regex that is the starting delimiter
584 for all markups. You can use a plain string or a qr// but you need to
585 escape (with \Q or \) any regex metachars if you want them to be plain
586 chars. The default is qr/\[%/.
588 my $tmpl = Template::Simple->new(
592 my $rendered = $tmpl->render( '<%FOO%]', 'bar' ) ;
596 This option sets the string or regex that is the ending delimiter
597 for all markups. You can use a plain string or a qr// but you need to
598 escape (with \Q or \) any regex metachars if you want them to be plain
599 chars. The default is qr/%]/.
601 my $tmpl = Template::Simple->new(
605 my $rendered = $tmpl->render( '[%FOO%>', 'bar' ) ;
609 This boolean option will cause the regex that grabs a chunk of text
610 between the C<START/END> markups to become greedy (.+). The default is
611 a not-greedy grab of the chunk text. (UNTESTED)
615 This option lets you load templates directly into the cache of the
616 Template::Simple object. This cache will be searched by the C<INCLUDE>
617 markup which will be replaced by the template if found. The option
618 value is a hash reference which has template names (the name in the
619 C<INCLUDE> markup) for keys and their template text as their
620 values. You can delete or clear templates from the object cache with
621 the C<delete_template> method.
624 my $tmpl = Template::Simple->new(
628 [%baz%] is a [%quux%]
631 [%user%] is not a [%fool%]
636 my $template = <<TMPL ;
640 my $rendered = $tmpl->render(
650 Template::Simple can also load C<INCLUDE> templates from files. This
651 option lets you set the directory paths to search for those
652 files. Note that the template name in the C<INCLUDE> markup has the
653 .tmpl suffix appended to it when searched for in one of these
654 paths. The loaded file is cached inside the Template::Simple object
655 along with any loaded by the C<templates> option.
663 This method is passed a template and a data tree and it renders it and
664 returns a reference to the resulting string. The template argument can
665 be a scalar or a scalar reference. The data tree argument can be any
666 value allowed by Template::Simple when rendering a template. It can
667 also be a blessed reference (Perl object) since
668 C<Scalar::Util::reftype> is used instead of C<ref> to determine the
671 Note that the author recommends against passing in an object as this
672 breaks encapsulation and forces your object to be (most likely) a
673 hash. It would be better to create a simple method that copies the
674 object contents to a hash reference and pass that. But current
675 templaters allow passing in objects so that is supported here as well.
677 my $rendered = $tmpl->render( $template, $data ) ;
681 This method adds templates to the object cache. It takes a list of template names and texts just like the C<templates> constructor option.
683 $tmpl->add_templates(
685 foo => \$foo_template,
686 bar => '[%include bar%]',
690 =head2 delete_templates
692 This method takes a list of template names and will delete them from
693 the template cache in the object. If you pass in an empty list then
694 all the templates will be deleted. This can be used when you know a
695 template file has been updated and you want to get it loaded back into
696 the cache. Note that you can delete templates that were loaded
697 directly (via the C<templates> constructor option or the
698 C<add_templates> method) or loaded from a file.
700 # this deletes only the foo and bar templates from the object cache
702 $tmpl->delete_templates( qw( foo bar ) ;
704 # this deletes all of templates from the object cache
706 $tmpl->delete_templates() ;
708 =head2 get_dependencies
710 This method render the only C<INCLUDE> markups of a template and it
711 returns a list of the file paths that were found and loaded. It is
712 meant to be used to build up a dependency list of included templates
713 for a main template. Typically this can be called from a script (see
714 TODO) that will do this for a set of main templates and will generate
715 Makefile dependencies for them. Then you can regenerate rendered
716 templates only when any of their included templates have changed. It
717 takes a single argument of a template.
719 UNKNOWN: will this require a clearing of the cache or will it do the
720 right thing on its own? or will it use the file path cache?
723 $tmpl->get_dependencies( '[%INCLUDE top_level%]' );
727 All the markups in Template::Simple use the same delimiters which are
728 C<[%> and C<%]>. You can change the delimiters with the C<pre_delim>
729 and C<post_delim> options in the C<new()> constructor.
733 A token is a single markup with a C<\w+> Perl word inside. The token
734 can have optional whitespace before and after it. A token is replaced
735 by a value looked up in a hash with the token as the key. The hash
736 lookup keeps the same case as parsed from the token markup.
740 Those will be replaced by C<$href->{foo}> and C<$href->{BAR}> assuming
741 C<$href> is the current data for this rendering. Tokens are only
742 parsed out during hash data rendering so see Hash Data for more.
746 Chunks are regions of text in a template that are marked off with a
747 start and end markers with the same name. A chunk start marker is
748 C<[%START name%]> and the end marker for that chunk is C<[%END
749 name%]>. C<name> is a C<\w+> Perl word which is the name of this
750 chunk. The whitespace between C<START/END> and C<name> is required and
751 there is optional whitespace before C<START/END> and after the
752 C<name>. C<START/END> are case insensitive but the C<name>'s case is
753 kept. C<name> must match in the C<START/END> pair and it used as a key
754 in a hash data rendering. Chunks are the primary way to markup
755 templates for structures (sets of tokens), nesting (hashes of hashes),
756 repeats (array references) and callbacks to user code. Chunks are only
757 parsed out during hash data rendering so see Hash Data for more.
759 The body of text between the C<START/END> markups is grabbed with a
760 C<.+?> regular expression with the /s option enabled so it will match
761 all characters. By default it will be a non-greedy grab but you can
762 change that in the constructor by enabling the C<greedy_chunk> option.
772 =head1 RENDERING RULES
774 Template::Simple has a short list of rendering rules and they are easy
775 to understand. There are two types of renderings, include rendering
776 and chunk rendering. In the C<render> method, the template is an
777 unnamed top level chunk of text and it first gets its C<INCLUDE>
778 markups rendered. The text then undergoes a chunk rendering and a
779 scalar reference to that rendered template is returned to the caller.
781 =head2 Include Rendering
783 Include rendering is performed one time on a top level template. When
784 it is done the template is ready for chunk rendering. Any markup of
785 the form C<[%INCLUDE name]%> will be replaced by the text found in the
786 template C<name>. The template name is looked up in the object's
787 template cache and if it is found there its text is used as the
790 If a template is not found in the cache, it will be searched for in
791 the list of directories in the C<include_paths> option. The file name
792 will be a directory in that list appended with the template name and
793 the C<.tmpl> suffix. The first template file found will be read in and
794 stored in the cache. Its path is also saved and those will be returned
795 in the C<get_dependencies> method. See the C<add_templates> and
796 C<delete_templates> methods and the C<include_paths> option.
798 Rendered include text can contain more C<INCLUDE> markups and they
799 will also be rendered. The include rendering phase ends where there
800 are no more C<INCLUDE> found.
802 =head2 Chunk Rendering
804 A chunk is the text found between C<START> and C<END> markups and it
805 gets its named from the C<START> markup. The top level template is
806 considered an unamed chunk and also gets chunk rendered.
808 The data for a chunk determines how it will be rendered. The data can
809 be a scalar or scalar reference or an array, hash or code
810 reference. Since chunks can contain nested chunks, rendering will
811 recurse down the data tree as it renders the chunks. Each of these
812 renderings are explained below. Also see the IDIOMS and BEST PRACTICES
813 section for examples and used of these renderings.
815 =head2 Scalar Data Rendering
817 If the current data for a chunk is a scalar or scalar reference, the
818 chunk's text in the templated is replaced by the scalar's value. This
819 can be used to overwrite one default section of text with from the
822 =head2 Code Data Rendering
824 If the current data for a chunk is a code reference (also called
825 anonymous sub) then the code reference is called and it is passed a
826 scalar reference to the that chunk's text. The code must return a
827 scalar or a scalar reference and its value replaces the chunk's text
828 in the template. If the code returns any other type of data it is a
829 fatal error. Code rendering is how you can do custom renderings and
830 plugins. A key idiom is to use closures as the data in code renderings
831 and keep the required outside data in the closure.
833 =head2 Array Data Rendering
835 If the current data for a chunk is an array reference do a full chunk
836 rendering for each value in the array. It will replace the original
837 chunk text with the joined list of rendered chunks. This is how you do
838 repeated sections in Template::Simple and why there is no need for any
839 loop markups. Note that this means that rendering a chunk with $data
840 and [ $data ] will do the exact same thing. A value of an empty array
841 C<[]> will cause the chunk to be replaced by the empty string.
843 =head2 Hash Data Rendering
845 If the current data for a chunk is a hash reference then two phases of
846 rendering happen, nested chunk rendering and token rendering. First
847 nested chunks are parsed of of this chunk along with their names. Each
848 parsed out chunk is rendered based on the value in the current hash
849 with the nested chunk's name as the key.
851 If a value is not found (undefined), then the nested chunk is replaced
852 by the empty string. Otherwise the nested chunk is rendered according
853 to the type of its data (see chunk rendering) and it is replaced by
856 Chunk name and token lookup in the hash data is case sensitive (see
857 the TODO for cased lookups).
859 Note that to keep a plain text chunk or to just have the all of its
860 markups (chunks and tokens) be deleted just pass in an empty hash
861 reference C<{}> as the data for the chunk. It will be rendered but all
862 markups will be replaced by the empty string.
864 =head2 Token Rendering
866 The second phase is token rendering. Markups of the form [%token%] are
867 replaced by the value of the hash element with the token as the
868 key. If a token's value is not defined it is replaced by the empty
869 string. This means if a token key is missing in the hash or its value
870 is undefined or its value is the empty string, the [%token%] markup
871 will be deleted in the rendering.
873 =head1 IDIOMS and BEST PRACTICES
875 With all template systems there are better ways to do things and
876 Template::Simple is no different. This section will show some ways to
877 handle typical template needs while using only the 4 markups in this
882 This conditional idiom can be when building a fresh data tree or
883 modifying an existing one.
885 $href->{$chunk_name} = $keep_chunk ? {} : '' ;
887 If you are building a fresh data tree you can use this idiom to do a
890 $href->{$chunk_name} = {} if $keep_chunk ;
892 To handle an if/else conditional use two chunks, with the else chunk's
893 name prefixed with NOT_ (or use any name munging you want). Then you
894 set the data for either the true chunk (just the plain name) or the
895 false trunk with the NOT_ name. You can use a different name for the
896 else chunk if you want but keeping the names of the if/else chunks
897 related is a good idea. Here are two ways to set the if/else data. The
898 first one uses the same data for both the if and else chunks and the
899 second one uses different data so the it uses the full if/else code
902 $href->{ ($boolean ? '' : 'NOT_') . $chunk_name} = $data
905 $href->{ $chunk_name} = $true_data ;
907 $href->{ "NOT_$chunk_name" } = $false_data ;
910 NOTE TO ALPHA USERS: i am also thinking that a non-existing key or
911 undefined hash value should leave the chunk as is. then you would need
912 to explicitly replace a chunk with the empty string if you wanted it
913 deleted. It does affect the list of styles idiom. Any thoughts on
914 this change of behavior? Since this hasn't been released it is the
917 =head2 Chunked Includes
919 One of the benefits of using include templates is the ability to share
920 and reuse existing work. But if an included template has a top level
921 named chunk, then that name would also be the same everywhere where
922 this template is included. If a template included another template in
923 multiple places, its data tree would use the same name for each and
924 not allow unique data to be rendered for each include. A better way is
925 to have the current template wrap an include markup in a named chunk
926 markup. Then the data tree could use unique names for each included
927 template. Here is how it would look:
929 [%START foo_prime%][%INCLUDE foo%][%START foo_prime%]
931 [%START foo_second%][%INCLUDE foo%][%START foo_second%]
933 See the TODO section for some ideas on how to make this even more high level.
935 =head2 Repeated Sections
937 If you looked at the markup of Template::Simple you have noticed that
938 there is no loop or repeat construct. That is because there is no need
939 for one. Any chunk can be rendered in a loop just by having its
940 rendering data be an anonymous array. The renderer will loop over each
941 element of the array and do a fresh rendering of the chunk with this
942 data. A join (on '') of the list of renderings replaces the original
943 chunk and you have a repeated chunk.
945 =head2 A List of Mixed Styles
947 One formating style is to have a list of sections each which can have
948 its own style or content. Template::Simple can do this very easily
949 with just a 2 level nested chunk and an array of data for
950 rendering. The outer chunk includes (or contains) each of the desired
951 styles in any order. It looks like this:
953 [%START para_styles%]
955 [%INCLUDE para_style_main%]
958 [%INCLUDE para_style_sub%]
960 [%START footer_style%]
961 [%INCLUDE para_style_footer%]
965 The other part to make this work is in the data tree. The data for
966 para_styles should be a list of hashes. Each hash contains the data
967 for one pargraph style which is keyed by the style's chunk name. Since
968 the other styles's chunk names are not hash they are deleted. Only the
969 style which has its name as a key in the hash is rendered. The data
970 tree would look something like this:
974 main_style => $main_data,
977 sub_style => $sub_data,
980 sub_style => $other_sub_data,
983 footer_style => $footer_data,
989 The test scripts use a common test driver module in t/common.pl. It is
990 passed a list of hashes, each of which has the data for one test. A
991 test can create a ne Template::Simple object or use the one from the
992 previous test. The template source, the data tree and the expected
993 results are also important keys. See the test scripts for examples of
994 how to write tests using this common driver.
1000 This is the name of the test and is used by Test::More
1004 This is a hash ref of the options passed to the Template::Simple
1005 constructor. The object is not built if the C<keep_obj> key is set.
1009 If set, this will make this test keep the Template::Simple object from
1010 the previous test and not build a new one.
1014 This is the template to render for this test. If not set, the test
1015 driver will use the template from the previous test. This is useful to
1016 run a series of test variants with the same template.
1020 This is the data tree for the rendering of the template.
1024 This is the text that is expected after the rendering.
1028 If set, this test is skipped.
1034 Even though this template system is simple, that doesn't mean it can't
1035 be extended in many ways. Here are some features and designs that
1036 would be good extensions which add useful functionality without adding
1037 too much complexity.
1039 =head2 Compiled Templates
1041 A commonly performed optimization in template modules is to precompile
1042 (really preparse) templates into a internal form that will render
1043 faster. Precompiling is slower than rendering from the original
1044 template which means you won't want to do it for each rendering. This
1045 means it has a downside that you lose out when you want to render
1046 using templates which change often. Template::Simple makes it very
1047 easy to precompile as it already has the regexes to parse out the
1048 markup. So instead of calling subs to do actual rendering, a
1049 precompiler would call subs to generate a compiled rendering tree.
1050 The rendering tree can then be run or processes with rendering data
1051 passed to it. You can think of a precompiled template as having all
1052 the nested chunks be replaced by nested code that does the same
1053 rendering. It can still do the dynamic rendering of the data but it
1054 saves the time of parsing the template souice. There are three
1055 possible internal formats for the precompiled template:
1061 This precompiler will generate source code that can be stored and/or
1062 eval'ed. The eval'ed top level sub can then be called and passed the
1065 =item Closure call tree
1067 The internal format can be a nested set of closures. Each closure would contain
1068 private data such as fixed text parts of the original template, lists
1069 of other closures to run, etc. It is trivial to write a basic closure
1070 generator which will make build this tree a simple task.
1072 =item Code ref call tree
1074 This format is a Perl data tree where the nodes have a code reference
1075 and its args (which can be nested instances of the same
1076 nodes). Instead of executing this directly, you will need a small
1077 interpreter to execute all the code refs as it runs through the tree.
1079 This would make for a challenging project to any intermediate Perl
1080 hacker. It just involves knowing recursion, data trees and code refs.
1081 Contact me if you are interested in doing this.
1085 =head2 Cased Hash Lookups
1087 One possible option is to allow hash renderings to always use upper or
1088 lower cased keys in their lookups.
1090 =head2 Render tokens before includes and chunks
1092 Currently tokens are rendered after includes and chunks. If tokens
1093 were rendered in a pass before the others, the include and chunk names
1094 could be dynamically set. This would make it harder to precompile
1095 templates as too much would be dynamic, i.e. you won't know what the
1096 fixed text to parse out is since anything can be included at render
1097 time. But the extra flexibility of changing the include and chunk
1098 names would be interesting. It could be done easily and enabled by an
1103 There are two different potential areas in Template::Simple that could
1104 use plugins. The first is with the rendering of chunkas and
1105 dispatching based on the data type. This dispatch table can easily be
1106 replaced by loaded modules which offer a different way to
1107 render. These include the precompiled renderers mentioned above. The
1108 other area is with code references as the data type. By defining a
1109 closure (or a closure making) API you can create different code refs
1110 for the rendering data. The range of plugins is endless some of the
1111 major template modules have noticed. One idea is to make a closure
1112 which contains a different Template::Simple object than the current
1113 one. This will allow rendering of a nested chunk with different rules
1114 than the current chunk being rendered.
1116 =head2 Data Escaping
1118 Some templaters have options to properly escape data for some types of
1119 text files such as html. this can be done with some variant of the
1120 _render_hash routine which also does the scalar rendering (which is
1121 where data is rendered). The rendering scalars code could be factored
1122 out into a set of subs one of which is used based on any escaping
1125 =head2 Data Tree is an Object
1127 This is a concept I don't like but it was requested so it goes into
1128 the TODO file. Currently C<render> can only be passed a regular
1129 (unblessed) ref (or a scalar) for its data tree. Passing in an object
1130 would break encapsulation and force the object layout to be a hash
1131 tree that matches the layout of the template. I doubt that most
1132 objects will want to be organized to match a template. I have two
1133 ideas, one is that you add a method to that object that builds up a
1134 proper (unblessed) data tree to pass to C<render>. The other is by
1135 subclassing C<Template::Simple> and overriding C<render> with a sub
1136 that does take an object hash and it can unbless it or build a proper
1137 data tree and then call C<render> in SUPER::. A quick solution is to
1138 use C<reftype> (from Scalar::Utils) instead of C<ref> to allow object
1139 hashes to be passed in.
1141 =head2 Includes and Closure Synergy
1143 By pairing up an include template along with code that can generate
1144 the appropriate data tree for its rendering, you can create a higher
1145 level template framework (the synergy). Additional code can be
1146 associated with them that will handle input processing and
1147 verification for the templates (e.g. web forms) that need it. A key to
1148 this will be making all the closures for the data tree. This can be
1149 greatly simplified by using a closure maker sub that can create all
1150 the required closures.
1152 =head2 Metafields and UI Generation
1154 Taking the synergy up to a much higher level is the concept of meta
1155 knowledge of fields which can generate templates, output processing
1156 (data tree generation), input processing, DB backing and more. If you
1157 want to discuss such grandiose wacky application schemes in a long
1158 rambling mind bending conversation, please contact me.
1160 =head2 More Examples and Idioms
1162 As I convert several scripts over to this module (they all used the
1163 hack version), I will add them to an examples section or possibly put
1164 them in another (pod only) module. Similarly the Idioms section needs
1165 rendering and could be also put into a pod module. One goal requested
1166 by an early alpha tester is to keep the primary docs as simple as the
1167 markup itself. This means moving all the extra stuff (and plenty of
1168 that) into other pod modules. All the pod modules would be in the same
1169 cpan tarball so you get all the docs and examples when you install
1174 Uri Guttman, C<< <uri at sysarch.com> >>
1178 Please report any bugs or feature requests to
1179 C<bug-template-simple at rt.cpan.org>, or through the web interface at
1180 L<http://rt.cpan.org/NoAuth/ReportBug.html?Queue=Template-Simple>.
1181 I will be notified, and then you'll automatically be notified of progress on
1182 your bug as I make changes.
1186 You can find documentation for this module with the perldoc command.
1188 perldoc Template::Simple
1190 You can also look for information at:
1194 =item * RT: CPAN's request tracker
1196 L<http://rt.cpan.org/NoAuth/Bugs.html?Dist=Template-Simple>
1200 L<http://search.cpan.org/dist/Template-Simple>
1204 =head1 ACKNOWLEDGEMENTS
1206 I wish to thank Turbo10 for their support in developing this module.
1208 =head1 COPYRIGHT & LICENSE
1210 Copyright 2006 Uri Guttman, all rights reserved.
1212 This program is free software; you can redistribute it and/or modify it
1213 under the same terms as Perl itself.
1218 find templates and tests
1226 delete_templates test
1234 slurp dependency in makefile.pl