1Template::Alloy::TT(3)User Contributed Perl DocumentationTemplate::Alloy::TT(3)
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6 Template::Alloy::TT - Template::Toolkit role
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9 The Template::Alloy::TT role provides the syntax and the interface for
10 Template::Toolkit version 1, 2, and 3. It also brings many of the
11 features from the various templating systems.
12 And it is fast.
14 See the Template::Alloy documentation for configuration and other
16 parameters.
17
19 Alloy uses the same base template syntax and configuration items as
20 TT2, but the internals of Alloy were written from scratch.
21 Additionally much of the planned TT3 syntax is supported as well as
22 most of that of HTML::Template::Expr. The following is a list of some
23 of the ways that the configuration and syntax of Alloy are different
24 from that of TT2. Note: items that are planned to work in TT3 are
25 marked with (TT3).
26 · Numerical hash keys work
28 [% a = {1 => 2} %]
30 · Quoted hash key interpolation is fine
32 [% a = {"$foo" => 1} %]
34 · Multiple ranges in same constructor
36 [% a = [1..10, 21..30] %]
38 · Constructor types can call virtual methods. (TT3)
40 [% a = [1..10].reverse %]
42 [% "$foo".length %]
44 [% 123.length %] # = 3
46 [% 123.4.length %] # = 5
48 [% -123.4.length %] # = -5 ("." binds more tightly than "-")
50 [% (a ~ b).length %]
52 [% "hi".repeat(3) %] # = hihihi
54 [% {a => b}.size %] # = 1
56 · The "${" and "}" variable interpolators can contain expressions,
58 not just variables.
59 [% [0..10].${ 1 + 2 } %] # = 4
61 [% {ab => 'AB'}.${ 'a' ~ 'b' } %] # = AB
63 [% color = qw/Red Blue/; FOR [1..4] ; color.${ loop.index % color.size } ; END %]
65 # = RedBlueRedBlue
66 · You can use regular expression quoting.
68 [% "foo".match( /(F\w+)/i ).0 %] # = foo
70 · Tags can be nested.
72 [% f = "[% (1 + 2) %]" %][% f|eval %] # = 3
74 · Arrays can be accessed with non-integer numbers.
76 [% [0..10].${ 2.3 } %] # = 3
78 · Reserved names are less reserved. (TT3)
80 [% GET GET %] # gets the variable named "GET"
82 [% GET $GET %] # gets the variable who's name is stored in "GET"
84 · Filters and SCALAR_OPS are interchangeable. (TT3)
86 [% a | length %]
88 [% b . lower %]
90 · Pipe "|" can be used anywhere dot "." can be and means to call the
92 virtual method. (TT3)
93 [% a = {size => "foo"} %][% a.size %] # = foo
95 [% a = {size => "foo"} %][% a|size %] # = 1 (size of hash)
97 · Pipe "|" and "." can be mixed. (TT3)
99 [% "aa" | repeat(2) . length %] # = 4
101 · Added V2PIPE configuration item
103 Restores the behavior of the pipe operator to be compatible with
105 TT2.
106 With V2PIPE = 1
108 [% PROCESS a | repeat(2) %] # = value of block or file a repeated twice
110 With V2PIPE = 0 (default)
112 [% PROCESS a | repeat(2) %] # = process block or file named a ~ a
114 · Added V2EQUALS configuration item
116 Allows for turning off TT2 "==" behavior. Defaults to 1 in TT
118 syntaxes and to 0 in HT syntaxes.
119 [% CONFIG V2EQUALS => 1 %][% ('7' == '7.0') || 0 %]
121 [% CONFIG V2EQUALS => 0 %][% ('7' == '7.0') || 0 %]
122 Prints
124 0
126 1
127 · Added AUTO_EVAL configuration item.
129 Default false. If true, will automatically call eval filter on
131 double quoted strings.
132 · Added SHOW_UNDEFINED_INTERP configuration item.
134 Default false. If true, will leave in place interpolated values
136 that weren't defined. You can then use the Velocity notation $!foo
137 to not show these values.
138 · Added Virtual Object Namespaces. (TT3)
140 The Text, List, and Hash types give direct access to virtual
142 methods.
143 [% a = "foobar" %][% Text.length(a) %] # = 6
145 [% a = [1 .. 10] %][% List.size(a) %] # = 10
147 [% a = {a=>"A", b=>"B"} ; Hash.size(a) %] = 2
149 [% foo = {a => 1, b => 2}
151 | Hash.keys
152 | List.join(", ") %] # = a, b
153 · Added "fmt" scalar, list, and hash virtual methods.
155 [% list.fmt("%s", ", ") %]
157 [% hash.fmt("%s => %s", "\n") %]
159 · Added missing HTML::Template::Expr vmethods
161 The following vmethods were added - they correspond to the perl
163 functions of the same name.
164 abs
166 atan2
167 cos
168 exp
169 hex
170 lc
171 log
172 oct
173 sin
174 sprintf
175 sqrt
176 srand
177 uc
178 · Allow all Scalar vmethods to behave as top level functions.
180 [% sprintf("%d %d", 7, 8) %] # = "7 8"
182 The following are equivalent in Alloy:
184 [% "abc".length %]
186 [% length("abc") %]
187 This feature may be disabling by setting the VMETHOD_FUNCTIONS
189 configuration item to 0.
190 This is similar to how HTML::Template::Expr operates, but now you
192 can use this functionality in TT templates as well.
193 · Whitespace is less meaningful. (TT3)
195 [% 2-1 %] # = 1 (fails in TT2)
197 · Added pow operator.
199 [% 2 ** 3 %] [% 2 pow 3 %] # = 8 8
201 · Added string comparison operators (gt ge lt le cmp)
203 [% IF "a" lt "b" %]a is less[% END %]
205 · Added numeric comparison operator (<=>)
207 This can be used to make up for the fact that TT2 made == the same
209 as eq (which will hopefully change - use eq when you mean eq).
210 [% IF ! (a <=> b) %]a == b[% END %]
212 [% IF (a <=> b) %]a != b[% END %]
214 · Added self modifiers (+=, -=, *=, /=, %=, **=, ~=). (TT3)
216 [% a = 2; a *= 3 ; a %] # = 6
218 [% a = 2; (a *= 3) ; a %] # = 66
219 · Added pre and post increment and decrement (++ --). (TT3)
221 [% ++a ; ++a %] # = 12
223 [% a-- ; a-- %] # = 0-1
224 · Added qw// contructor. (TT3)
226 [% a = qw(a b c); a.1 %] # = b
228 [% qw/a b c/.2 %] # = c
230 · Added regex contructor. (TT3)
232 [% "FOO".match(/(foo)/i).0 %] # = FOO
234 [% a = /(foo)/i; "FOO".match(a).0 %] # = FOO
236 · Allow for scientific notation. (TT3)
238 [% a = 1.2e-20 %]
240 [% 123.fmt('%.3e') %] # = 1.230e+02
242 · Allow for hexadecimal input. (TT3)
244 [% a = 0xff0000 %][% a %] # = 16711680
246 [% a = 0xff2 / 0xd; a.fmt('%x') %] # = 13a
248 · FOREACH variables can be nested.
250 [% FOREACH f.b = [1..10] ; f.b ; END %]
252 Note that nested variables are subject to scoping issues. f.b will
254 not be reset to its value before the FOREACH.
255 · Post operative directives can be nested. (TT3)
257 Andy Wardley calls this side-by-side effect notation.
259 [% one IF two IF three %]
261 same as
263 [% IF three %][% IF two %][% one %][% END %][% END %]
265 [% a = [[1..3], [5..7]] %][% i FOREACH i = j FOREACH j = a %] # = 123567
268 · Semi-colons on directives in the same tag are optional. (TT3)
270 [% SET a = 1
272 GET a
273 %]
274 [% FOREACH i = [1 .. 10]
276 i
277 END %]
278 Note: a semi-colon is still required in front of any block
280 directive that can be used as a post-operative directive.
281 [% 1 IF 0
283 2 %] # prints 2
284 [% 1; IF 0
286 2
287 END %] # prints 1
288 Note2: This behavior can be disabled by setting the SEMICOLONS
290 configuration item to a true value. If SEMICOLONS is true, then a
291 SEMICOLON must be set after any directive that isn't followed by a
292 post-operative directive.
293 · CATCH blocks can be empty.
295 TT2 requires them to contain something.
297 · Added a DUMP directive.
299 Used for Data::Dumper'ing the passed variable or expression.
301 [% DUMP a.a %]
303 · Added CONFIG directive.
305 [% CONFIG
307 ANYCASE => 1
308 PRE_CHOMP => '-'
309 %]
310 · Configuration options can use lowercase names instead of the all
312 uppercase names that TT2 uses.
313 my $t = Template::Alloy->new({
315 anycase => 1,
316 interpolate => 1,
317 });
318 · Added LOOP directive (works the same as LOOP in HTML::Template.
320 [%- var = [{key => 'a'}, {key => 'b'}] %]
322 [%- LOOP var %]
323 ([% key %])
324 [%- END %]
325 Prints
327 (a)
329 (b)
330 · Alloy can parse HTML::Template and HTML::Template::Expr documents
332 as well as TT2 and TT3 documents.
333 · Added SYNTAX configuration. The SYNTAX configuration can be used
335 to change what template syntax will be used for parsing included
336 templates or eval'ed strings.
337 [% CONFIG SYNTAX => 'hte' %]
339 [% var = '<TMPL_VAR EXPR="sprintf('%s', 'hello world')">' %]
340 [% var | eval %]
341 · Added @() and $() and CALL_CONTEXT. Template::Toolkit uses a
343 \concept that Alloy refers to as "smart" context. All function
344 calls or method calls of variables in Template::Toolkit are made in
345 list context. If one item is in the list, it is returned. If two
346 or more items are returned - it returns an arrayref. This "does
347 the right thing" most of the time - but can cause confusion in some
348 cases and is difficult to work around without writing wrappers for
349 the functions or methods in Perl.
350 Alloy has introduced the CALL_CONTEXT configuration item which
352 defaults to "smart," but can also be set to "list" or "item." List
353 context will always return an arrayref from called functions and
354 methods and will call in list context. Item context will always
355 call in item (scalar) context and will return one item.
356 The @() and $() operators allow for functions embedded inside to
358 use list and item context (respectively). They are modeled after
359 the corresponding Perl 6 context specifiers. See the
360 Template::Alloy::Operators perldoc and CALL_CONTEXT configuration
361 documentation for more information.
362 [% array = @( this.get_rows ) %]
364 [% item = $( this.get_something ) %]
366 · Added ->() MACRO operator.
368 The ->() operator behaves similarly to the MACRO directive, but can
370 be used to pass functions to map, grep, and sort vmethods.
371 [% MACRO foo(n) BLOCK %]Say [% n %][% END %]
373 [% foo = ->(n){ "Say $n" } %]
374 [% [0..10].grep(->(this % 2)).join %] prints 3 5 7 9
376 [% ['a' .. 'c'].map(->(a){ a.upper }).join %] prints A B C
377 [% [1,2,3].sort(->(a,b){ b <=> a }).join %] prints 3 2 1
378 · The RETURN directive can take a variable or expression as a return
380 value. Their are also "return" list, item, and hash vmethods.
381 Return will also return from an enclosing MACRO.
382 [% a = ->(n){ [1..n].return } %]
384 · Alloy does not generate Perl code.
386 It generates an "opcode" tree. The opcode tree is an arrayref of
388 scalars and array refs nested as deeply as possible. This "simple"
389 structure could be shared TT implementations in other languages via
390 JSON or YAML. You can optionally enable generating Perl code by
391 setting COMPILE_PERL = 1.
392 · Alloy uses storable for its compiled templates.
394 If EVAL_PERL is off, Alloy will not eval_string on ANY piece of
396 information.
397 · There is eval_filter and MACRO recursion protection
399 You can control the nested nature of eval_filter and MACRO
401 recursion using the MAX_EVAL_RECURSE and MAX_MACRO_RECURSE
402 configuration items.
403 · There is no context.
405 Alloy provides a context object that mimics the Template::Context
407 interface for use by some TT filters, eval perl blocks, views, and
408 plugins.
409 · There is no provider.
411 Alloy uses the load_template method to get and cache templates.
413 · There is no parser/grammar.
415 Alloy has its own built-in recursive regex based parser and grammar
417 system.
418 Alloy can actually be substituted in place of the native
420 Template::Parser and Template::Grammar in TT by using the
421 Template::Parser::Alloy module. This module uses the output of
422 parse_tree to generate a TT style compiled perl document.
423 · The DEBUG directive is more limited.
425 It only understands DEBUG_DIRS (8) and DEBUG_UNDEF (2).
427 · Alloy has better line information
429 When debug dirs is on, directives on different lines separated by
431 colons show the line they are on rather than a general line range.
432 Parse errors actually know what line and character they occurred
434 at.
435
437 LOAD_TEMPLATES
438 Template::Alloy has its own mechanism for loading and storing
439 compiled templates. TT would use a Template::Provider that would
440 return a Template::Document. The closest thing in Template::Alloy
441 is the load_template method. There is no immediate plan to support
442 the TT behavior.
443 LOAD_PLUGINS
445 Template::Alloy uses its own mechanism for loading plugins. TT
446 would use a Template::Plugins object to load plugins requested via
447 the USE directive. The functionality for doing this in
448 Template::Alloy is contained in the list_plugins method and the
449 play_USE method. There is no immediate plan to support the TT
450 behavior.
451 Full support is offered for the PLUGINS and LOAD_PERL configuration
453 items.
454 Also note that Template::Alloy only has native support for the
456 Iterator plugin. Any of the other plugins requested will need to
457 provided by installing Template::Toolkit or the appropriate plugin
458 module.
459 LOAD_FILTERS
461 Template::Alloy uses its own mechanism for loading filters. TT
462 would use the Template::Filters object to load filters requested
463 via the FILTER directive. The functionality for doing this in
464 Template::Alloy is contained in the list_filters method and the
465 play_expr method.
466 Full support is offered for the FILTERS configuration item.
468 TOLERANT
470 This option is used by the LOAD_TEMPLATES and LOAD_PLUGINS options
471 and is not applicable in Template::Alloy.
472 SERVICE
474 Template::Alloy has no concept of service (theoretically the
475 Template::Alloy is the "service").
476 CONTEXT
478 Template::Alloy provides its own pseudo context object to plugins,
479 filters, and perl blocks. The Template::Alloy model doesn't really
480 allow for a separate context. Template::Alloy IS the context.
481 PARSER
483 Template::Alloy has its own built in parser. The closest
484 similarity is the parse_tree method. The output of parse_tree is
485 an optree that is later run by execute_tree. Alloy provides a
486 backend to the Template::Parser::Alloy module which can be used to
487 replace the default parser when using the standard
488 Template::Toolkit library.
489 GRAMMAR
491 Template::Alloy maintains its own grammar. The grammar is defined
492 in the parse_tree method and the callbacks listed in the global
493 $Template::Alloy::Parse::DIRECTIVES hashref.
494
496 Paul Seamons <paul@seamons.com>
497
499 This module may be distributed under the same terms as Perl itself.
500perl v5.32.1 2021-03-23 Template::Alloy::TT(3)