1HTML::Template(3)     User Contributed Perl Documentation    HTML::Template(3)
2
3
4

NAME

6       HTML::Template - Perl module to use HTML-like templating language
7

SYNOPSIS

9       First you make a template - this is just a normal HTML file with a few
10       extra tags, the simplest being "<TMPL_VAR>"
11
12       For example, test.tmpl:
13
14           <html>
15           <head><title>Test Template</title></head>
16           <body>
17           My Home Directory is <TMPL_VAR NAME=HOME>
18           <p>
19           My Path is set to <TMPL_VAR NAME=PATH>
20           </body>
21           </html>
22
23       Now you can use it in a small CGI program:
24
25           #!/usr/bin/perl -w
26           use HTML::Template;
27
28           # open the html template
29           my $template = HTML::Template->new(filename => 'test.tmpl');
30
31           # fill in some parameters
32           $template->param(HOME => $ENV{HOME});
33           $template->param(PATH => $ENV{PATH});
34
35           # send the obligatory Content-Type and print the template output
36           print "Content-Type: text/html\n\n", $template->output;
37
38       If all is well in the universe this should show something like this in
39       your browser when visiting the CGI:
40
41           My Home Directory is /home/some/directory
42           My Path is set to /bin;/usr/bin
43

DESCRIPTION

45       This module attempts to make using HTML templates simple and natural.
46       It extends standard HTML with a few new HTML-esque tags - "<TMPL_VAR>"
47       "<TMPL_LOOP>", "<TMPL_INCLUDE>", "<TMPL_IF>", "<TMPL_ELSE>" and
48       "<TMPL_UNLESS>".  The file written with HTML and these new tags is
49       called a template.  It is usually saved separate from your script -
50       possibly even created by someone else!  Using this module you fill in
51       the values for the variables, loops and branches declared in the
52       template.  This allows you to separate design - the HTML - from the
53       data, which you generate in the Perl script.
54
55       This module is licensed under the same terms as Perl. See the LICENSE
56       section below for more details.
57

TUTORIAL

59       If you're new to HTML::Template, I suggest you start with the
60       introductory article available on Perl Monks:
61
62           http://www.perlmonks.org/?node_id=65642
63

FAQ

65       Please see HTML::Template::FAQ
66

MOTIVATION

68       It is true that there are a number of packages out there to do HTML
69       templates.  On the one hand you have things like HTML::Embperl which
70       allows you freely mix Perl with HTML.  On the other hand lie home-grown
71       variable substitution solutions.  Hopefully the module can find a place
72       between the two.
73
74       One advantage of this module over a full HTML::Embperl-esque solution
75       is that it enforces an important divide - design and programming.  By
76       limiting the programmer to just using simple variables and loops in the
77       HTML, the template remains accessible to designers and other non-perl
78       people.  The use of HTML-esque syntax goes further to make the format
79       understandable to others.  In the future this similarity could be used
80       to extend existing HTML editors/analyzers to support HTML::Template.
81
82       An advantage of this module over home-grown tag-replacement schemes is
83       the support for loops.  In my work I am often called on to produce
84       tables of data in html.  Producing them using simplistic HTML templates
85       results in programs containing lots of HTML since the HTML itself
86       cannot represent loops.  The introduction of loop statements in the
87       HTML simplifies this situation considerably.  The designer can layout a
88       single row and the programmer can fill it in as many times as necessary
89       - all they must agree on is the parameter names.
90
91       For all that, I think the best thing about this module is that it does
92       just one thing and it does it quickly and carefully.  It doesn't try to
93       replace Perl and HTML, it just augments them to interact a little
94       better.  And it's pretty fast.
95

THE TAGS

97   TMPL_VAR
98           <TMPL_VAR NAME="PARAMETER_NAME">
99
100       The "<TMPL_VAR>" tag is very simple.  For each "<TMPL_VAR>" tag in the
101       template you call:
102
103           $template->param(PARAMETER_NAME => "VALUE")
104
105       When the template is output the "<TMPL_VAR>" is replaced with the VALUE
106       text you specified.  If you don't set a parameter it just gets skipped
107       in the output.
108
109       You can also specify the value of the parameter as a code reference in
110       order to have "lazy" variables. These sub routines will only be
111       referenced if the variables are used. See "LAZY VALUES" for more
112       information.
113
114       Attributes
115
116       The following "attributes" can also be specified in template var tags:
117
118       ·   escape
119
120           This allows you to escape the value before it's put into the
121           output.
122
123           This is useful when you want to use a TMPL_VAR in a context where
124           those characters would cause trouble. For example:
125
126              <input name=param type=text value="<TMPL_VAR PARAM>">
127
128           If you called "param()" with a value like "sam"my" you'll get in
129           trouble with HTML's idea of a double-quote.  On the other hand, if
130           you use "escape=html", like this:
131
132              <input name=param type=text value="<TMPL_VAR PARAM ESCAPE=HTML>">
133
134           You'll get what you wanted no matter what value happens to be
135           passed in for param.
136
137           The following escape values are supported:
138
139           ·   html
140
141               Replaces the following characters with their HTML entity
142               equivalent: "&", """, "'", "<", ">"
143
144           ·   js
145
146               Escapes (with a backslash) the following characters: "\", "'",
147               """, "\n", "\r"
148
149           ·   url
150
151               URL escapes any ASCII characters except for letters, numbers,
152               "_", "." and "-".
153
154           ·   none
155
156               Performs no escaping. This is the default, but it's useful to
157               be able to explicitly turn off escaping if you are using the
158               "default_escape" option.
159
160       ·   default
161
162           With this attribute you can assign a default value to a variable.
163           For example, this will output "the devil gave me a taco" if the
164           "who" variable is not set.
165
166               <TMPL_VAR WHO DEFAULT="the devil"> gave me a taco.
167
168   TMPL_LOOP
169           <TMPL_LOOP NAME="LOOP_NAME"> ... </TMPL_LOOP>
170
171       The "<TMPL_LOOP>" tag is a bit more complicated than "<TMPL_VAR>".  The
172       "<TMPL_LOOP>" tag allows you to delimit a section of text and give it a
173       name.  Inside this named loop you place "<TMPL_VAR>"s.  Now you pass to
174       "param()" a list (an array ref) of parameter assignments (hash refs)
175       for this loop.  The loop iterates over the list and produces output
176       from the text block for each pass.  Unset parameters are skipped.
177       Here's an example:
178
179       In the template:
180
181          <TMPL_LOOP NAME=EMPLOYEE_INFO>
182             Name: <TMPL_VAR NAME=NAME> <br>
183             Job:  <TMPL_VAR NAME=JOB>  <p>
184          </TMPL_LOOP>
185
186       In your Perl code:
187
188           $template->param(
189               EMPLOYEE_INFO => [{name => 'Sam', job => 'programmer'}, {name => 'Steve', job => 'soda jerk'}]
190           );
191           print $template->output();
192
193       The output is:
194
195           Name: Sam
196           Job: programmer
197
198           Name: Steve
199           Job: soda jerk
200
201       As you can see above the "<TMPL_LOOP>" takes a list of variable
202       assignments and then iterates over the loop body producing output.
203
204       Often you'll want to generate a "<TMPL_LOOP>"'s contents
205       programmatically.  Here's an example of how this can be done (many
206       other ways are possible!):
207
208           # a couple of arrays of data to put in a loop:
209           my @words     = qw(I Am Cool);
210           my @numbers   = qw(1 2 3);
211           my @loop_data = ();              # initialize an array to hold your loop
212
213           while (@words and @numbers) {
214               my %row_data;      # get a fresh hash for the row data
215
216               # fill in this row
217               $row_data{WORD}   = shift @words;
218               $row_data{NUMBER} = shift @numbers;
219
220               # the crucial step - push a reference to this row into the loop!
221               push(@loop_data, \%row_data);
222           }
223
224           # finally, assign the loop data to the loop param, again with a reference:
225           $template->param(THIS_LOOP => \@loop_data);
226
227       The above example would work with a template like:
228
229           <TMPL_LOOP NAME="THIS_LOOP">
230             Word: <TMPL_VAR NAME="WORD">
231             Number: <TMPL_VAR NAME="NUMBER">
232
233           </TMPL_LOOP>
234
235       It would produce output like:
236
237           Word: I
238           Number: 1
239
240           Word: Am
241           Number: 2
242
243           Word: Cool
244           Number: 3
245
246       "<TMPL_LOOP>"s within "<TMPL_LOOP>"s are fine and work as you would
247       expect.  If the syntax for the "param()" call has you stumped, here's
248       an example of a param call with one nested loop:
249
250           $template->param(
251               LOOP => [
252                   {
253                       name      => 'Bobby',
254                       nicknames => [{name => 'the big bad wolf'}, {name => 'He-Man'}],
255                   },
256               ],
257           );
258
259       Basically, each "<TMPL_LOOP>" gets an array reference.  Inside the
260       array are any number of hash references.  These hashes contain the
261       name=>value pairs for a single pass over the loop template.
262
263       Inside a "<TMPL_LOOP>", the only variables that are usable are the ones
264       from the "<TMPL_LOOP>".  The variables in the outer blocks are not
265       visible within a template loop.  For the computer-science geeks among
266       you, a "<TMPL_LOOP>" introduces a new scope much like a perl subroutine
267       call.  If you want your variables to be global you can use
268       "global_vars" option to "new()" described below.
269
270   TMPL_INCLUDE
271           <TMPL_INCLUDE NAME="filename.tmpl">
272
273       This tag includes a template directly into the current template at the
274       point where the tag is found.  The included template contents are used
275       exactly as if its contents were physically included in the master
276       template.
277
278       The file specified can be an absolute path (beginning with a '/' under
279       Unix, for example).  If it isn't absolute, the path to the enclosing
280       file is tried first.  After that the path in the environment variable
281       "HTML_TEMPLATE_ROOT" is tried, if it exists.  Next, the "path" option
282       is consulted, first as-is and then with "HTML_TEMPLATE_ROOT" prepended
283       if available.  As a final attempt, the filename is passed to "open()"
284       directly.  See below for more information on "HTML_TEMPLATE_ROOT" and
285       the "path" option to "new()".
286
287       As a protection against infinitely recursive includes, an arbitrary
288       limit of 10 levels deep is imposed.  You can alter this limit with the
289       "max_includes" option.  See the entry for the "max_includes" option
290       below for more details.
291
292   TMPL_IF
293           <TMPL_IF NAME="PARAMETER_NAME"> ... </TMPL_IF>
294
295       The "<TMPL_IF>" tag allows you to include or not include a block of the
296       template based on the value of a given parameter name.  If the
297       parameter is given a value that is true for Perl - like '1' - then the
298       block is included in the output.  If it is not defined, or given a
299       false value - like '0' - then it is skipped.  The parameters are
300       specified the same way as with "<TMPL_VAR>".
301
302       Example Template:
303
304           <TMPL_IF NAME="BOOL">
305             Some text that only gets displayed if BOOL is true!
306           </TMPL_IF>
307
308       Now if you call "$template->param(BOOL => 1)" then the above block will
309       be included by output.
310
311       "<TMPL_IF> </TMPL_IF>" blocks can include any valid HTML::Template
312       construct - "VAR"s and "LOOP"s and other "IF"/"ELSE" blocks.  Note,
313       however, that intersecting a "<TMPL_IF>" and a "<TMPL_LOOP>" is
314       invalid.
315
316           Not going to work:
317           <TMPL_IF BOOL>
318             <TMPL_LOOP SOME_LOOP>
319           </TMPL_IF>
320             </TMPL_LOOP>
321
322       If the name of a "<TMPL_LOOP>" is used in a "<TMPL_IF>", the "IF" block
323       will output if the loop has at least one row.  Example:
324
325           <TMPL_IF LOOP_ONE>
326             This will output if the loop is not empty.
327           </TMPL_IF>
328
329           <TMPL_LOOP LOOP_ONE>
330             ....
331           </TMPL_LOOP>
332
333       WARNING: Much of the benefit of HTML::Template is in decoupling your
334       Perl and HTML.  If you introduce numerous cases where you have
335       "TMPL_IF"s and matching Perl "if"s, you will create a maintenance
336       problem in keeping the two synchronized.  I suggest you adopt the
337       practice of only using "TMPL_IF" if you can do so without requiring a
338       matching "if" in your Perl code.
339
340   TMPL_ELSE
341           <TMPL_IF NAME="PARAMETER_NAME"> ... <TMPL_ELSE> ... </TMPL_IF>
342
343       You can include an alternate block in your "<TMPL_IF>" block by using
344       "<TMPL_ELSE>".  NOTE: You still end the block with "</TMPL_IF>", not
345       "</TMPL_ELSE>"!
346
347          Example:
348           <TMPL_IF BOOL>
349             Some text that is included only if BOOL is true
350           <TMPL_ELSE>
351             Some text that is included only if BOOL is false
352           </TMPL_IF>
353
354   TMPL_UNLESS
355           <TMPL_UNLESS NAME="PARAMETER_NAME"> ... </TMPL_UNLESS>
356
357       This tag is the opposite of "<TMPL_IF>".  The block is output if the
358       "PARAMETER_NAME" is set false or not defined.  You can use
359       "<TMPL_ELSE>" with "<TMPL_UNLESS>" just as you can with "<TMPL_IF>".
360
361           Example:
362           <TMPL_UNLESS BOOL>
363             Some text that is output only if BOOL is FALSE.
364           <TMPL_ELSE>
365             Some text that is output only if BOOL is TRUE.
366           </TMPL_UNLESS>
367
368       If the name of a "<TMPL_LOOP>" is used in a "<TMPL_UNLESS>", the
369       "<UNLESS>" block output if the loop has zero rows.
370
371           <TMPL_UNLESS LOOP_ONE>
372             This will output if the loop is empty.
373           </TMPL_UNLESS>
374
375           <TMPL_LOOP LOOP_ONE>
376             ....
377           </TMPL_LOOP>
378
379   NOTES
380       HTML::Template's tags are meant to mimic normal HTML tags.  However,
381       they are allowed to "break the rules".  Something like:
382
383           <img src="<TMPL_VAR IMAGE_SRC>">
384
385       is not really valid HTML, but it is a perfectly valid use and will work
386       as planned.
387
388       The "NAME=" in the tag is optional, although for extensibility's sake I
389       recommend using it.  Example - "<TMPL_LOOP LOOP_NAME>" is acceptable.
390
391       If you're a fanatic about valid HTML and would like your templates to
392       conform to valid HTML syntax, you may optionally type template tags in
393       the form of HTML comments. This may be of use to HTML authors who would
394       like to validate their templates' HTML syntax prior to HTML::Template
395       processing, or who use DTD-savvy editing tools.
396
397         <!-- TMPL_VAR NAME=PARAM1 -->
398
399       In order to realize a dramatic savings in bandwidth, the standard (non-
400       comment) tags will be used throughout this documentation.
401

METHODS

403   new
404       Call "new()" to create a new Template object:
405
406           my $template = HTML::Template->new(
407               filename => 'file.tmpl',
408               option   => 'value',
409           );
410
411       You must call "new()" with at least one "name =" value> pair specifying
412       how to access the template text.  You can use "filename => 'file.tmpl'"
413       to specify a filename to be opened as the template.  Alternately you
414       can use:
415
416           my $t = HTML::Template->new(
417               scalarref => $ref_to_template_text,
418               option    => 'value',
419           );
420
421       and
422
423           my $t = HTML::Template->new(
424               arrayref => $ref_to_array_of_lines,
425               option   => 'value',
426           );
427
428       These initialize the template from in-memory resources.  In almost
429       every case you'll want to use the filename parameter.  If you're
430       worried about all the disk access from reading a template file just use
431       mod_perl and the cache option detailed below.
432
433       You can also read the template from an already opened filehandle,
434       either traditionally as a glob or as a FileHandle:
435
436           my $t = HTML::Template->new(filehandle => *FH, option => 'value');
437
438       The four "new()" calling methods can also be accessed as below, if you
439       prefer.
440
441           my $t = HTML::Template->new_file('file.tmpl', option => 'value');
442
443           my $t = HTML::Template->new_scalar_ref($ref_to_template_text, option => 'value');
444
445           my $t = HTML::Template->new_array_ref($ref_to_array_of_lines, option => 'value');
446
447           my $t = HTML::Template->new_filehandle($fh, option => 'value');
448
449       And as a final option, for those that might prefer it, you can call new
450       as:
451
452           my $t = HTML::Template->new(
453               type   => 'filename',
454               source => 'file.tmpl',
455           );
456
457       Which works for all three of the source types.
458
459       If the environment variable "HTML_TEMPLATE_ROOT" is set and your
460       filename doesn't begin with "/", then the path will be relative to the
461       value of c<HTML_TEMPLATE_ROOT>.
462
463       Example - if the environment variable "HTML_TEMPLATE_ROOT" is set to
464       /home/sam and I call "HTML::Template->new()" with filename set to
465       "sam.tmpl", HTML::Template will try to open /home/sam/sam.tmpl to
466       access the template file.  You can also affect the search path for
467       files with the "path" option to "new()" - see below for more
468       information.
469
470       You can modify the Template object's behavior with "new()". The options
471       are available:
472
473       Error Detection Options
474
475       ·   die_on_bad_params
476
477           If set to 0 the module will let you call:
478
479               $template->param(param_name => 'value')
480
481           even if 'param_name' doesn't exist in the template body.  Defaults
482           to 1.
483
484       ·   force_untaint
485
486           If set to 1 the module will not allow you to set unescaped
487           parameters with tainted values. If set to 2 you will have to
488           untaint all parameters, including ones with the escape attribute.
489           This option makes sure you untaint everything so you don't
490           accidentally introduce e.g. cross-site-scripting (XSS)
491           vulnerabilities. Requires taint mode. Defaults to 0.
492
493       ·   strict - if set to 0 the module will allow things that look like
494           they might be TMPL_* tags to get by without dieing.  Example:
495
496               <TMPL_HUH NAME=ZUH>
497
498           Would normally cause an error, but if you call new with "strict =>
499           0" HTML::Template will ignore it.  Defaults to 1.
500
501       ·   vanguard_compatibility_mode
502
503           If set to 1 the module will expect to see "<TMPL_VAR>"s that look
504           like "%NAME%" in addition to the standard syntax.  Also sets
505           "die_on_bad_params =" 0>.  If you're not at Vanguard Media trying
506           to use an old format template don't worry about this one.  Defaults
507           to 0.
508
509       Caching Options
510
511       ·   cache
512
513           If set to 1 the module will cache in memory the parsed templates
514           based on the filename parameter, the modification date of the file
515           and the options passed to "new()". This only applies to templates
516           opened with the filename parameter specified, not scalarref or
517           arrayref templates.  Caching also looks at the modification times
518           of any files included using "<TMPL_INCLUDE>" tags, but again, only
519           if the template is opened with filename parameter.
520
521           This is mainly of use in a persistent environment like
522           Apache/mod_perl.  It has absolutely no benefit in a normal CGI
523           environment since the script is unloaded from memory after every
524           request.  For a cache that does work for a non-persistent
525           environment see the "shared_cache" option below.
526
527           My simplistic testing shows that using cache yields a 90%
528           performance increase under mod_perl.  Cache defaults to 0.
529
530       ·   shared_cache
531
532           If set to 1 the module will store its cache in shared memory using
533           the IPC::SharedCache module (available from CPAN).  The effect of
534           this will be to maintain a single shared copy of each parsed
535           template for all instances of HTML::Template on the same machine to
536           use.  This can be a significant reduction in memory usage in an
537           environment with a single machine but multiple servers.  As an
538           example, on one of our systems we use 4MB of template cache and
539           maintain 25 httpd processes - shared_cache results in saving almost
540           100MB!  Of course, some reduction in speed versus normal caching is
541           to be expected.  Another difference between normal caching and
542           shared_cache is that shared_cache will work in a non-persistent
543           environment (like normal CGI) - normal caching is only useful in a
544           persistent environment like Apache/mod_perl.
545
546           By default HTML::Template uses the IPC key 'TMPL' as a shared root
547           segment (0x4c504d54 in hex), but this can be changed by setting the
548           "ipc_key" "new()" parameter to another 4-character or integer key.
549           Other options can be used to affect the shared memory cache
550           correspond to IPC::SharedCache options - "ipc_mode",
551           "ipc_segment_size" and "ipc_max_size".  See IPC::SharedCache for a
552           description of how these work - in most cases you shouldn't need to
553           change them from the defaults.
554
555           For more information about the shared memory cache system used by
556           HTML::Template see IPC::SharedCache.
557
558       ·   double_cache
559
560           If set to 1 the module will use a combination of "shared_cache" and
561           normal cache mode for the best possible caching.  Of course, it
562           also uses the most memory of all the cache modes.  All the same
563           ipc_* options that work with "shared_cache" apply to "double_cache"
564           as well. Defaults to 0.
565
566       ·   blind_cache
567
568           If set to 1 the module behaves exactly as with normal caching but
569           does not check to see if the file has changed on each request.
570           This option should be used with caution, but could be of use on
571           high-load servers.  My tests show "blind_cache" performing only 1
572           to 2 percent faster than cache under mod_perl.
573
574           NOTE: Combining this option with shared_cache can result in stale
575           templates stuck permanently in shared memory!
576
577       ·   file_cache
578
579           If set to 1 the module will store its cache in a file using the
580           Storable module.  It uses no additional memory, and my simplistic
581           testing shows that it yields a 50% performance advantage.  Like
582           "shared_cache", it will work in a non-persistent environments (like
583           CGI). Default is 0.
584
585           If you set this option you must set the "file_cache_dir" option.
586           See below for details.
587
588           NOTE: Storable uses "flock()" to ensure safe access to cache files.
589           Using "file_cache" on a system or filesystem (like NFS) without
590           "flock()" support is dangerous.
591
592       ·   file_cache_dir
593
594           Sets the directory where the module will store the cache files if
595           "file_cache" is enabled.  Your script will need write permissions
596           to this directory.  You'll also need to make sure the sufficient
597           space is available to store the cache files.
598
599       ·   file_cache_dir_mode
600
601           Sets the file mode for newly created "file_cache" directories and
602           subdirectories.  Defaults to "0700" for security but this may be
603           inconvenient if you do not have access to the account running the
604           webserver.
605
606       ·   double_file_cache
607
608           If set to 1 the module will use a combination of "file_cache" and
609           normal "cache" mode for the best possible caching.  The
610           file_cache_* options that work with file_cache apply to
611           "double_file_cache" as well.  Defaults to 0.
612
613       ·   cache_lazy_vars
614
615           The option tells HTML::Template to cache the values returned from
616           code references used for "TMPL_VAR"s. See "LAZY VALUES" for
617           details.
618
619       ·   cache_lazy_loops
620
621           The option tells HTML::Template to cache the values returned from
622           code references used for "TMPL_LOOP"s. See "LAZY VALUES" for
623           details.
624
625       Filesystem Options
626
627       ·   path
628
629           You can set this variable with a list of paths to search for files
630           specified with the "filename" option to "new()" and for files
631           included with the "<TMPL_INCLUDE>" tag.  This list is only
632           consulted when the filename is relative.  The "HTML_TEMPLATE_ROOT"
633           environment variable is always tried first if it exists.  Also, if
634           "HTML_TEMPLATE_ROOT" is set then an attempt will be made to prepend
635           "HTML_TEMPLATE_ROOT" onto paths in the path array.  In the case of
636           a "<TMPL_INCLUDE>" file, the path to the including file is also
637           tried before path is consulted.
638
639           Example:
640
641               my $template = HTML::Template->new(
642                   filename => 'file.tmpl',
643                   path     => ['/path/to/templates', '/alternate/path'],
644               );
645
646           NOTE: the paths in the path list must be expressed as UNIX paths,
647           separated by the forward-slash character ('/').
648
649       ·   search_path_on_include
650
651           If set to a true value the module will search from the top of the
652           array of paths specified by the path option on every
653           "<TMPL_INCLUDE>" and use the first matching template found.  The
654           normal behavior is to look only in the current directory for a
655           template to include.  Defaults to 0.
656
657       ·   utf8
658
659           Setting this to true tells HTML::Template to treat your template
660           files as UTF-8 encoded.  This will apply to any file's passed to
661           "new()" or any included files. It won't do anything special to
662           scalars templates passed to "new()" since you should be doing the
663           encoding on those yourself.
664
665               my $template = HTML::Template->new(
666                   filename => 'umlauts_are_awesome.tmpl',
667                   utf8     => 1,
668               );
669
670           Most templates are either ASCII (the default) or UTF-8 encoded
671           Unicode. But if you need some other encoding other than these 2,
672           look at the "open_mode" option.
673
674           NOTE: The "utf8" and "open_mode" options cannot be used at the same
675           time.
676
677       ·   open_mode
678
679           You can set this option to an opening mode with which all template
680           files will be opened.
681
682           For example, if you want to use a template that is UTF-16 encoded
683           unicode:
684
685               my $template = HTML::Template->new(
686                   filename  => 'file.tmpl',
687                   open_mode => '<:encoding(UTF-16)',
688               );
689
690           That way you can force a different encoding (than the default ASCII
691           or UTF-8), CR/LF properties etc. on the template files. See PerlIO
692           for details.
693
694           NOTE: this only works in perl 5.7.1 and above.
695
696           NOTE: you have to supply an opening mode that actually permits
697           reading from the file handle.
698
699           NOTE: The "utf8" and "open_mode" options cannot be used at the same
700           time.
701
702       Debugging Options
703
704       ·   debug
705
706           If set to 1 the module will write random debugging information to
707           STDERR.  Defaults to 0.
708
709       ·   stack_debug
710
711           If set to 1 the module will use Data::Dumper to print out the
712           contents of the parse_stack to STDERR.  Defaults to 0.
713
714       ·   cache_debug
715
716           If set to 1 the module will send information on cache loads, hits
717           and misses to STDERR.  Defaults to 0.
718
719       ·   shared_cache_debug
720
721           If set to 1 the module will turn on the debug option in
722           IPC::SharedCache. Defaults to 0.
723
724       ·   memory_debug
725
726           If set to 1 the module will send information on cache memory usage
727           to STDERR.  Requires the GTop module.  Defaults to 0.
728
729       Miscellaneous Options
730
731       ·   associate
732
733           This option allows you to inherit the parameter values from other
734           objects.  The only requirement for the other object is that it have
735           a "param()" method that works like HTML::Template's "param()".  A
736           good candidate would be a CGI query object. Example:
737
738               my $query    = CGI->new;
739               my $template = HTML::Template->new(
740                   filename  => 'template.tmpl',
741                   associate => $query,
742               );
743
744           Now, "$template->output()" will act as though
745
746               $template->param(form_field => $cgi->param('form_field'));
747
748           had been specified for each key/value pair that would be provided
749           by the "$cgi->param()" method.  Parameters you set directly take
750           precedence over associated parameters.
751
752           You can specify multiple objects to associate by passing an
753           anonymous array to the associate option.  They are searched for
754           parameters in the order they appear:
755
756               my $template = HTML::Template->new(
757                   filename  => 'template.tmpl',
758                   associate => [$query, $other_obj],
759               );
760
761           NOTE: The parameter names are matched in a case-insensitive manner.
762           If you have two parameters in a CGI object like 'NAME' and 'Name'
763           one will be chosen randomly by associate.  This behavior can be
764           changed by the "case_sensitive" option.
765
766       ·   case_sensitive
767
768           Setting this option to true causes HTML::Template to treat template
769           variable names case-sensitively.  The following example would only
770           set one parameter without the "case_sensitive" option:
771
772               my $template = HTML::Template->new(
773                   filename       => 'template.tmpl',
774                   case_sensitive => 1
775               );
776               $template->param(
777                   FieldA => 'foo',
778                   fIELDa => 'bar',
779               );
780
781           This option defaults to off.
782
783           NOTE: with "case_sensitive" and "loop_context_vars" the special
784           loop variables are available in lower-case only.
785
786       ·   loop_context_vars
787
788           When this parameter is set to true (it is false by default) extra
789           variables that depend on the loop's context are made available
790           inside a loop. These are:
791
792           ·   __first__
793
794               Value that is true for the first iteration of the loop and
795               false every other time.
796
797           ·   __last__
798
799               Value that is true for the last iteration of the loop and false
800               every other time.
801
802           ·   __inner__
803
804               Value that is true for the every iteration of the loop except
805               for the first and last.
806
807           ·   __outer__
808
809               Value that is true for the first and last iterations of the
810               loop.
811
812           ·   __odd__
813
814               Value that is true for the every odd iteration of the loop.
815
816           ·   __even__
817
818               Value that is true for the every even iteration of the loop.
819
820           ·   __counter__
821
822               An integer (starting from 1) whose value increments for each
823               iteration of the loop.
824
825           ·   __index__
826
827               An integer (starting from 0) whose value increments for each
828               iteration of the loop.
829
830           Just like any other "TMPL_VAR"s these variables can be used in
831           "<TMPL_IF>", "<TMPL_UNLESS>" and "<TMPL_ELSE>" to control how a
832           loop is output.
833
834           Example:
835
836               <TMPL_LOOP NAME="FOO">
837                 <TMPL_IF NAME="__first__">
838                   This only outputs on the first pass.
839                 </TMPL_IF>
840
841                 <TMPL_IF NAME="__odd__">
842                   This outputs every other pass, on the odd passes.
843                 </TMPL_IF>
844
845                 <TMPL_UNLESS NAME="__odd__">
846                   This outputs every other pass, on the even passes.
847                 </TMPL_UNLESS>
848
849                 <TMPL_IF NAME="__inner__">
850                   This outputs on passes that are neither first nor last.
851                 </TMPL_IF>
852
853                 This is pass number <TMPL_VAR NAME="__counter__">.
854
855                 <TMPL_IF NAME="__last__">
856                   This only outputs on the last pass.
857                 </TMPL_IF>
858               </TMPL_LOOP>
859
860           One use of this feature is to provide a "separator" similar in
861           effect to the perl function "join()".  Example:
862
863               <TMPL_LOOP FRUIT>
864                 <TMPL_IF __last__> and </TMPL_IF>
865                 <TMPL_VAR KIND><TMPL_UNLESS __last__>, <TMPL_ELSE>.</TMPL_UNLESS>
866               </TMPL_LOOP>
867
868           Would output something like:
869
870             Apples, Oranges, Brains, Toes, and Kiwi.
871
872           Given an appropriate "param()" call, of course. NOTE: A loop with
873           only a single pass will get both "__first__" and "__last__" set to
874           true, but not "__inner__".
875
876       ·   no_includes
877
878           Set this option to 1 to disallow the "<TMPL_INCLUDE>" tag in the
879           template file.  This can be used to make opening untrusted
880           templates slightly less dangerous.  Defaults to 0.
881
882       ·   max_includes
883
884           Set this variable to determine the maximum depth that includes can
885           reach.  Set to 10 by default.  Including files to a depth greater
886           than this value causes an error message to be displayed.  Set to 0
887           to disable this protection.
888
889       ·   die_on_missing_include
890
891           If true, then HTML::Template will die if it can't find a file for a
892           "<TMPL_INCLUDE>". This defaults to true.
893
894       ·   global_vars
895
896           Normally variables declared outside a loop are not available inside
897           a loop.  This option makes "<TMPL_VAR>"s like global variables in
898           Perl - they have unlimited scope.  This option also affects
899           "<TMPL_IF>" and "<TMPL_UNLESS>".
900
901           Example:
902
903               This is a normal variable: <TMPL_VAR NORMAL>.<P>
904
905               <TMPL_LOOP NAME=FROOT_LOOP>
906                 Here it is inside the loop: <TMPL_VAR NORMAL><P>
907               </TMPL_LOOP>
908
909           Normally this wouldn't work as expected, since "<TMPL_VAR
910           NORMAL>"'s value outside the loop is not available inside the loop.
911
912           The global_vars option also allows you to access the values of an
913           enclosing loop within an inner loop.  For example, in this loop the
914           inner loop will have access to the value of "OUTER_VAR" in the
915           correct iteration:
916
917               <TMPL_LOOP OUTER_LOOP>
918                 OUTER: <TMPL_VAR OUTER_VAR>
919                   <TMPL_LOOP INNER_LOOP>
920                      INNER: <TMPL_VAR INNER_VAR>
921                      INSIDE OUT: <TMPL_VAR OUTER_VAR>
922                   </TMPL_LOOP>
923               </TMPL_LOOP>
924
925           One side-effect of "global_vars" is that variables you set with
926           "param()" that might otherwise be ignored when "die_on_bad_params"
927           is off will stick around.  This is necessary to allow inner loops
928           to access values set for outer loops that don't directly use the
929           value.
930
931           NOTE: "global_vars" is not "global_loops" (which does not exist).
932           That means that loops you declare at one scope are not available
933           inside other loops even when "global_vars" is on.
934
935       ·   filter
936
937           This option allows you to specify a filter for your template files.
938           A filter is a subroutine that will be called after HTML::Template
939           reads your template file but before it starts parsing template
940           tags.
941
942           In the most simple usage, you simply assign a code reference to the
943           filter parameter.  This subroutine will receive a single argument -
944           a reference to a string containing the template file text.  Here is
945           an example that accepts templates with tags that look like
946           "!!!ZAP_VAR FOO!!!" and transforms them into HTML::Template tags:
947
948               my $filter = sub {
949                   my $text_ref = shift;
950                   $$text_ref =~ s/!!!ZAP_(.*?)!!!/<TMPL_$1>/g;
951               };
952
953               # open zap.tmpl using the above filter
954               my $template = HTML::Template->new(
955                   filename => 'zap.tmpl',
956                   filter   => $filter,
957               );
958
959           More complicated usages are possible.  You can request that your
960           filter receives the template text as an array of lines rather than
961           as a single scalar.  To do that you need to specify your filter
962           using a hash-ref.  In this form you specify the filter using the
963           "sub" key and the desired argument format using the "format" key.
964           The available formats are "scalar" and "array".  Using the "array"
965           format will incur a performance penalty but may be more convenient
966           in some situations.
967
968               my $template = HTML::Template->new(
969                   filename => 'zap.tmpl',
970                   filter   => {
971                       sub    => $filter,
972                       format => 'array',
973                   }
974               );
975
976           You may also have multiple filters.  This allows simple filters to
977           be combined for more elaborate functionality.  To do this you
978           specify an array of filters.  The filters are applied in the order
979           they are specified.
980
981               my $template = HTML::Template->new(
982                   filename => 'zap.tmpl',
983                   filter   => [
984                       {
985                           sub    => \&decompress,
986                           format => 'scalar',
987                       },
988                       {
989                           sub    => \&remove_spaces,
990                           format => 'array',
991                       },
992                   ]
993               );
994
995           The specified filters will be called for any "TMPL_INCLUDE"ed files
996           just as they are for the main template file.
997
998       ·   default_escape
999
1000           Set this parameter to a valid escape type (see the "escape" option)
1001           and HTML::Template will apply the specified escaping to all
1002           variables unless they declare a different escape in the template.
1003
1004   config
1005       A package method that is used to set/get the global default
1006       configuration options.  For instance, if you want to set the "utf8"
1007       flag to always be on for every template loaded by this process you
1008       would do:
1009
1010           HTML::Template->config(utf8 => 1);
1011
1012       Or if you wanted to check if the "utf8" flag was on or not, you could
1013       do:
1014
1015           my %config = HTML::Template->config;
1016           if( $config{utf8} ) {
1017               ...
1018           }
1019
1020       Any configuration options that are valid for "new()" are acceptable to
1021       be passed to this method.
1022
1023   param
1024       "param()" can be called in a number of ways
1025
1026       1 - To return a list of parameters in the template :
1027               my @parameter_names = $self->param();
1028
1029       2 - To return the value set to a param :
1030               my $value = $self->param('PARAM');
1031
1032       3 - To set the value of a parameter :
1033               # For simple TMPL_VARs:
1034               $self->param(PARAM => 'value');
1035
1036               # with a subroutine reference that gets called to get the value
1037               # of the scalar.  The sub will receive the template object as a
1038               # parameter.
1039               $self->param(PARAM => sub { return 'value' });
1040
1041               # And TMPL_LOOPs:
1042               $self->param(LOOP_PARAM => [{PARAM => VALUE_FOR_FIRST_PASS}, {PARAM => VALUE_FOR_SECOND_PASS}]);
1043
1044       4 - To set the value of a number of parameters :
1045               # For simple TMPL_VARs:
1046               $self->param(
1047                   PARAM  => 'value',
1048                   PARAM2 => 'value'
1049               );
1050
1051               # And with some TMPL_LOOPs:
1052               $self->param(
1053                   PARAM              => 'value',
1054                   PARAM2             => 'value',
1055                   LOOP_PARAM         => [{PARAM => VALUE_FOR_FIRST_PASS}, {PARAM => VALUE_FOR_SECOND_PASS}],
1056                   ANOTHER_LOOP_PARAM => [{PARAM => VALUE_FOR_FIRST_PASS}, {PARAM => VALUE_FOR_SECOND_PASS}],
1057               );
1058
1059       5 - To set the value of a number of parameters using a hash-ref :
1060               $self->param(
1061                   {
1062                       PARAM              => 'value',
1063                       PARAM2             => 'value',
1064                       LOOP_PARAM         => [{PARAM => VALUE_FOR_FIRST_PASS}, {PARAM => VALUE_FOR_SECOND_PASS}],
1065                       ANOTHER_LOOP_PARAM => [{PARAM => VALUE_FOR_FIRST_PASS}, {PARAM => VALUE_FOR_SECOND_PASS}],
1066                   }
1067               );
1068
1069           An error occurs if you try to set a value that is tainted if the
1070           "force_untaint" option is set.
1071
1072   clear_params
1073       Sets all the parameters to undef. Useful internally, if nowhere else!
1074
1075   output
1076       "output()" returns the final result of the template.  In most
1077       situations you'll want to print this, like:
1078
1079           print $template->output();
1080
1081       When output is called each occurrence of "<TMPL_VAR NAME=name>" is
1082       replaced with the value assigned to "name" via "param()".  If a named
1083       parameter is unset it is simply replaced with ''.  "<TMPL_LOOP>"s are
1084       evaluated once per parameter set, accumulating output on each pass.
1085
1086       Calling "output()" is guaranteed not to change the state of the
1087       HTML::Template object, in case you were wondering.  This property is
1088       mostly important for the internal implementation of loops.
1089
1090       You may optionally supply a filehandle to print to automatically as the
1091       template is generated.  This may improve performance and lower memory
1092       consumption.  Example:
1093
1094           $template->output(print_to => *STDOUT);
1095
1096       The return value is undefined when using the "print_to" option.
1097
1098   query
1099       This method allow you to get information about the template structure.
1100       It can be called in a number of ways.  The simplest usage of query is
1101       simply to check whether a parameter name exists in the template, using
1102       the "name" option:
1103
1104           if ($template->query(name => 'foo')) {
1105               # do something if a variable of any type named FOO is in the template
1106           }
1107
1108       This same usage returns the type of the parameter.  The type is the
1109       same as the tag minus the leading 'TMPL_'.  So, for example, a
1110       "TMPL_VAR" parameter returns 'VAR' from "query()".
1111
1112           if ($template->query(name => 'foo') eq 'VAR') {
1113               # do something if FOO exists and is a TMPL_VAR
1114           }
1115
1116       Note that the variables associated with "TMPL_IF"s and "TMPL_UNLESS"s
1117       will be identified as 'VAR' unless they are also used in a "TMPL_LOOP",
1118       in which case they will return 'LOOP'.
1119
1120       "query()" also allows you to get a list of parameters inside a loop
1121       (and inside loops inside loops).  Example loop:
1122
1123           <TMPL_LOOP NAME="EXAMPLE_LOOP">
1124             <TMPL_VAR NAME="BEE">
1125             <TMPL_VAR NAME="BOP">
1126             <TMPL_LOOP NAME="EXAMPLE_INNER_LOOP">
1127               <TMPL_VAR NAME="INNER_BEE">
1128               <TMPL_VAR NAME="INNER_BOP">
1129             </TMPL_LOOP>
1130           </TMPL_LOOP>
1131
1132       And some query calls:
1133
1134           # returns 'LOOP'
1135           $type = $template->query(name => 'EXAMPLE_LOOP');
1136
1137           # returns ('bop', 'bee', 'example_inner_loop')
1138           @param_names = $template->query(loop => 'EXAMPLE_LOOP');
1139
1140           # both return 'VAR'
1141           $type = $template->query(name => ['EXAMPLE_LOOP', 'BEE']);
1142           $type = $template->query(name => ['EXAMPLE_LOOP', 'BOP']);
1143
1144           # and this one returns 'LOOP'
1145           $type = $template->query(name => ['EXAMPLE_LOOP', 'EXAMPLE_INNER_LOOP']);
1146
1147           # and finally, this returns ('inner_bee', 'inner_bop')
1148           @inner_param_names = $template->query(loop => ['EXAMPLE_LOOP', 'EXAMPLE_INNER_LOOP']);
1149
1150           # for non existent parameter names you get undef this returns undef.
1151           $type = $template->query(name => 'DWEAZLE_ZAPPA');
1152
1153           # calling loop on a non-loop parameter name will cause an error. This dies:
1154           $type = $template->query(loop => 'DWEAZLE_ZAPPA');
1155
1156       As you can see above the "loop" option returns a list of parameter
1157       names and both "name" and "loop" take array refs in order to refer to
1158       parameters inside loops.  It is an error to use "loop" with a parameter
1159       that is not a loop.
1160
1161       Note that all the names are returned in lowercase and the types are
1162       uppercase.
1163
1164       Just like "param()", "query()" with no arguments returns all the
1165       parameter names in the template at the top level.
1166

LAZY VALUES

1168       As mentioned above, both "TMPL_VAR" and "TMPL_LOOP" values can be code
1169       references.  These code references are only executed if the variable or
1170       loop is used in the template.  This is extremely useful if you want to
1171       make a variable available to template designers but it can be expensive
1172       to calculate, so you only want to do so if you have to.
1173
1174       Maybe an example will help to illustrate. Let's say you have a template
1175       like this:
1176
1177           <tmpl_if we_care>
1178             <tmpl_if life_universe_and_everything>
1179           </tmpl_if>
1180
1181       If "life_universe_and_everything" is expensive to calculate we can wrap
1182       it's calculation in a code reference and HTML::Template will only
1183       execute that code if "we_care" is also true.
1184
1185           $tmpl->param(life_universe_and_everything => sub { calculate_42() });
1186
1187       Your code reference will be given a single argument, the HTML::Template
1188       object in use. In the above example, if we wanted "calculate_42()" to
1189       have this object we'd do something like this:
1190
1191           $tmpl->param(life_universe_and_everything => sub { calculate_42(shift) });
1192
1193       This same approach can be used for "TMPL_LOOP"s too:
1194
1195           <tmpl_if we_care>
1196             <tmpl_loop needles_in_haystack>
1197               Found <tmpl_var __counter>!
1198             </tmpl_loop>
1199           </tmpl_if>
1200
1201       And in your Perl code:
1202
1203           $tmpl->param(needles_in_haystack => sub { find_needles() });
1204
1205       The only difference in the "TMPL_LOOP" case is that the subroutine
1206       needs to return a reference to an ARRAY, not just a scalar value.
1207
1208   Multiple Calls
1209       It's important to recognize that while this feature is designed to save
1210       processing time when things aren't needed, if you're not careful it can
1211       actually increase the number of times you perform your calculation.
1212       HTML::Template calls your code reference each time it seems your loop
1213       in the template, this includes the times that you might use the loop in
1214       a conditional ("TMPL_IF" or "TMPL_UNLESS"). For instance:
1215
1216           <tmpl_if we care>
1217             <tmpl_if needles_in_haystack>
1218                 <tmpl_loop needles_in_haystack>
1219                   Found <tmpl_var __counter>!
1220                 </tmpl_loop>
1221             <tmpl_else>
1222               No needles found!
1223             </tmpl_if>
1224           </tmpl_if>
1225
1226       This will actually call "find_needles()" twice which will be even worse
1227       than you had before.  One way to work around this is to cache the
1228       return value yourself:
1229
1230           my $needles;
1231           $tmpl->param(needles_in_haystack => sub { defined $needles ? $needles : $needles = find_needles() });
1232

BUGS

1234       I am aware of no bugs - if you find one, join the mailing list and tell
1235       us about it.  You can join the HTML::Template mailing-list by visiting:
1236
1237           http://lists.sourceforge.net/lists/listinfo/html-template-users
1238
1239       Of course, you can still email me directly ("sam@tregar.com") with
1240       bugs, but I reserve the right to forward bug reports to the mailing
1241       list.
1242
1243       When submitting bug reports, be sure to include full details, including
1244       the VERSION of the module, a test script and a test template
1245       demonstrating the problem!
1246
1247       If you're feeling really adventurous, HTML::Template has a publically
1248       available Git repository.  See below for more information in the PUBLIC
1249       GIT REPOSITORY section.
1250

CREDITS

1252       This module was the brain child of my boss, Jesse Erlbaum
1253       ("jesse@vm.com") at Vanguard Media (http://vm.com) .  The most original
1254       idea in this module - the "<TMPL_LOOP>" - was entirely his.
1255
1256       Fixes, Bug Reports, Optimizations and Ideas have been generously
1257       provided by:
1258
1259       ·   Richard Chen
1260
1261       ·   Mike Blazer
1262
1263       ·   Adriano Nagelschmidt Rodrigues
1264
1265       ·   Andrej Mikus
1266
1267       ·   Ilya Obshadko
1268
1269       ·   Kevin Puetz
1270
1271       ·   Steve Reppucci
1272
1273       ·   Richard Dice
1274
1275       ·   Tom Hukins
1276
1277       ·   Eric Zylberstejn
1278
1279       ·   David Glasser
1280
1281       ·   Peter Marelas
1282
1283       ·   James William Carlson
1284
1285       ·   Frank D. Cringle
1286
1287       ·   Winfried Koenig
1288
1289       ·   Matthew Wickline
1290
1291       ·   Doug Steinwand
1292
1293       ·   Drew Taylor
1294
1295       ·   Tobias Brox
1296
1297       ·   Michael Lloyd
1298
1299       ·   Simran Gambhir
1300
1301       ·   Chris Houser <chouser@bluweb.com>
1302
1303       ·   Larry Moore
1304
1305       ·   Todd Larason
1306
1307       ·   Jody Biggs
1308
1309       ·   T.J. Mather
1310
1311       ·   Martin Schroth
1312
1313       ·   Dave Wolfe
1314
1315       ·   uchum
1316
1317       ·   Kawai Takanori
1318
1319       ·   Peter Guelich
1320
1321       ·   Chris Nokleberg
1322
1323       ·   Ralph Corderoy
1324
1325       ·   William Ward
1326
1327       ·   Ade Olonoh
1328
1329       ·   Mark Stosberg
1330
1331       ·   Lance Thomas
1332
1333       ·   Roland Giersig
1334
1335       ·   Jere Julian
1336
1337       ·   Peter Leonard
1338
1339       ·   Kenny Smith
1340
1341       ·   Sean P. Scanlon
1342
1343       ·   Martin Pfeffer
1344
1345       ·   David Ferrance
1346
1347       ·   Gyepi Sam
1348
1349       ·   Darren Chamberlain
1350
1351       ·   Paul Baker
1352
1353       ·   Gabor Szabo
1354
1355       ·   Craig Manley
1356
1357       ·   Richard Fein
1358
1359       ·   The Phalanx Project
1360
1361       ·   Sven Neuhaus
1362
1363       ·   Michael Peters
1364
1365       ·   Jan Dubois
1366
1367       ·   Moritz Lenz
1368
1369       Thanks!
1370

WEBSITE

1372       You can find information about HTML::Template and other related modules
1373       at:
1374
1375          http://html-template.sourceforge.net
1376

PUBLIC GIT REPOSITORY

1378       HTML::Template now has a publicly accessible Git repository provided by
1379       GitHub (github.com).  You can access it by going to
1380       https://github.com/mpeters/html-template.  Give it a try!
1381

AUTHOR

1383       Sam Tregar, "sam@tregar.com"
1384

CO-MAINTAINER

1386       Michael Peters, "mpeters@plusthree.com"
1387

LICENSE

1389         HTML::Template : A module for using HTML Templates with Perl
1390         Copyright (C) 2000-2011 Sam Tregar (sam@tregar.com)
1391
1392         This module is free software; you can redistribute it and/or modify it
1393         under the same terms as Perl itself, which means using either:
1394
1395         a) the GNU General Public License as published by the Free Software
1396         Foundation; either version 1, or (at your option) any later version,
1397
1398         or
1399
1400         b) the "Artistic License" which comes with this module.
1401
1402         This program is distributed in the hope that it will be useful,
1403         but WITHOUT ANY WARRANTY; without even the implied warranty of
1404         MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See either
1405         the GNU General Public License or the Artistic License for more details.
1406
1407         You should have received a copy of the Artistic License with this
1408         module.  If not, I'll be glad to provide one.
1409
1410         You should have received a copy of the GNU General Public License
1411         along with this program. If not, write to the Free Software
1412         Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307
1413         USA
1414
1415
1416
1417perl v5.28.1                      2017-05-18                 HTML::Template(3)
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