Template::Manual::VMetUser(Contributed Perl DocumTemplate::Manual::VMethods(3)NAMETemplate::Manual::VMethods - Virtual Methods
Scalar Virtual Methodschunk(size)
Splits the value into a list of chunks of a certain size.
[% ccard_no = "1234567824683579";
ccard_no.chunk(4).join
%]
Output:
1234 5678 2468 3579
If the size is specified as a negative number then the text will be
chunked from right-to-left. This gives the correct grouping for
numbers, for example.
[% number = 1234567;
number.chunk(-3).join(',')
%]
Output:
1,234,567
collapse
Returns the text with any leading and trailing whitespace removed and
any internal sequences of whitespace converted to a single space
[% text = " The bird\n is the word" %]
[% text.collapse %] # The bird is the word
defined
Returns true if the value is defined.
[% user = get_user(uid) IF uid.defined %]
dquote
Returns the text with any double quote characters escaped with a
backslash prefix. Any newline characters in the text will be replaced
with "\n".
[% quote = 'He said "Oh really?"' %]
[% quote.dquote %] # He said \"Oh really?\"
hash
Return the value as a hash reference containing a single entry with the
key "value" indicating the original scalar value. As with the "list"
virtual method, this is generally used to help massage data into
different formats.
lcfirst
Returns the text with the first letter converted to lower case.
[% word = 'BIRD' %]
[% word.lcfirst %] # bIRD
length
Returns the length of the string representation of the item:
[% IF password.length < 8 %]
Password too short, dumbass!
[% END %]
list
Return the value as a single element list. This can be useful if you
have a variable which may contain a single item or a list and you want
to treat them equally. The "list" method can be called against a list
reference and will simply return the original reference, effectively a
no-op.
[% thing.list.size %] # thing can be a scalar or a list
lower
Returns the text in lower case.
[% word = 'BIRD' %]
[% word.lower %] # bird
match(pattern, global)
Performs a regular expression match on the string using the pattern
passed as an argument. If the pattern matches the string then the
method returns a reference to a list of any strings captured within
parenthesis in the pattern.
[% name = 'Larry Wall' %]
[% matches = name.match('(\w+) (\w+)') %]
[% matches.1 %], [% matches.0 %] # Wall, Larry
If the pattern does not match then the method returns false, rather
than returning an empty list which Perl and the Template Toolkit both
consider to be a true value. This allows you to write expression like
this.
[% "We're not worthy!" IF name.match('Larry Wall') %]
[% IF (matches = name.match('(\w+) (\w+)')) %]
pattern matches: [% matches.join(', ') %]
[% ELSE %]
pattern does not match
[% END %]
Any regex modifiers, like "/s", should be added in the regex using the
"(?s)" syntax. For example, to modify the regex to disregard
whitespace (the "/x" switch), use:
[% re = '(?x)
(\w+)
[ ]
(\w+)
';
matches = name.match(re);
%]
To perform a global search to match the pattern as many times as it
appears in the source string, provide a true value for the "global"
argument following the pattern.
[% text = 'bandanna';
text.match('an+', 1).join(', ) # an, ann
%]
repeat(n)
Repeat the string a specified number of times.
[% name = 'foo' %]
[% name.repeat(3) %] # foofoofoo
replace(search, replace)
Outputs the string with all instances of the first argument (specified
as a Perl regular expression) with the second.
[% name = 'foo, bar & baz' %]
[% name.replace('\W+', '_') %] # foo_bar_baz
You can use $1, $2, etc., to reference captured parts (in parentheses)
in the regular expression. Just be careful to single quote the
replacement string. If you use double quotes then TT will try and
interpolate the variables before passing the string to the "replace"
vmethod.
[% name = 'FooBarBaz' %]
[% name.replace('([A-Z])', ' $1') %] # Foo Bar Baz
remove(pattern)
Outputs the string with all instances of the pattern (specified as a
Perl regular expression) removed.
[% name = 'foo, bar & baz' %]
[% name.remove('\W+') %] # foobarbaz
search(pattern)
Performs a similar function to match but simply returns true if the
string matches the regular expression pattern passed as an argument.
[% name = 'foo bar baz' %]
[% name.search('bar') ? 'bar' : 'no bar' %] # bar
This virtual method is now deprecated in favour of match. Move along
now, there's nothing more to see here.
size
Always returns 1 for scalar values. This method is provided for
consistency with the hash and list size methods.
split(pattern)
Calls Perl's "split()" function to split a string into a list of
strings.
[% FOREACH dir IN mypath.split(':') %]
[% dir %]
[% END %]
substr(offset, length, replacement)
Returns a substring starting at "offset", for "length" characters.
[% str 'foo bar baz wiz waz woz') %]
[% str.substr(4, 3) %] # bar
If "length" is not specified then it returns everything from the
"offset" to the end of the string.
[% str.substr(12) %] # wiz waz woz
If both "length" and "replacement" are specified, then the method
replaces everything from "offset" for "length" characters with
$replacement. The substring removed from the string is then returned.
[% str.substr(0, 11, 'FOO') %] # foo bar baz
[% str %] # FOO wiz waz woz
squote
Returns the text with any single quote characters escaped with a
backslash prefix.
[% tim = "Tim O'Reilly" %]
[% tim.squote %] # Tim O\'Reilly
trim
Returns the text with any leading and trailing whitespace removed.
[% text = ' hello world ' %]
[% text.trim %] # hello world
ucfirst
Returns the text with the first letter converted to upper case.
[% word = 'bird' %]
[% word.ucfirst %] # Bird
upper
Returns the text in upper case.
[% word = 'bird' %]
[% word.upper %] # BIRD
Hash Virtual Methods
keys
Returns a list of keys in the hash. They are not returned in any
particular order, but the order is the same as for the corresponding
values method.
[% FOREACH key IN hash.keys %]
* [% key %]
[% END %]
If you want the keys in sorted order, use the list "sort" method.
[% FOREACH key IN hash.keys.sort %]
* [% key %]
[% END %]
Having got the keys in sorted order, you can then use variable
interpolation to fetch the value. This is shown in the following
example by the use of $key to fetch the item from "hash" whose key is
stored in the "key" variable.
[% FOREACH key IN hash.keys.sort %]
* [% key %] = [% hash.$key %]
[% END %]
Alternately, you can use the "pairs" method to get a list of key/value
pairs in sorted order.
values
Returns a list of the values in the hash. As with the "keys" method,
they are not returned in any particular order, although it is the same
order that the keys are returned in.
[% hash.values.join(', ') %]
items
Returns a list of both the keys and the values expanded into a single
list.
[% hash = {
a = 10
b = 20
};
hash.items.join(', ') # a, 10, b, 20
%]
each
This method currently returns the same thing as the "items" method.
However, please note that this method will change in the next major
version of the Template Toolkit (v3) to return the same thing as the
"pairs" method. This will be done in an effort to make these virtual
method more consistent with each other and how Perl works.
In anticipation of this, we recommend that you stop using "hash.each"
and instead use "hash.items".
pairs
This method returns a list of key/value pairs. They are returned in
sorted order according to the keys.
[% FOREACH pair IN product.pairs %]
* [% pair.key %] is [% pair.value %]
[% END %]
list
Returns the contents of the hash in list form. An argument can be
passed to indicate the desired items required in the list: "keys" to
return a list of the keys (same as "hash.keys"), "values" to return a
list of the values (same as "hash.values"), "each" to return as list of
key and values (same as "hash.each"), or "pairs" to return a list of
key/value pairs (same as "hash.pairs").
[% keys = hash.list('keys') %]
[% values = hash.list('values') %]
[% items = hash.list('each') %]
[% pairs = hash.list('pairs') %]
When called without an argument it currently returns the same thing as
the "pairs" method. However, please note that this method will change
in the next major version of the Template Toolkit (v3) to return a
reference to a list containing the single hash reference (as per the
scalar list method).
In anticipation of this, we recommend that you stop using "hash.list"
and instead use "hash.pairs".
sort, nsort
Return a list of the keys, sorted alphabetically ("sort") or
numerically ("nsort") according to the corresponding values in the
hash.
[% FOREACH n IN phones.sort %]
[% phones.$n %] is [% n %],
[% END %]
import
The "import" method can be called on a hash array to import the
contents of another hash array.
[% hash1 = {
foo = 'Foo'
bar = 'Bar'
}
hash2 = {
wiz = 'Wiz'
woz = 'Woz'
}
%]
[% hash1.import(hash2) %]
[% hash1.wiz %] # Wiz
You can also call the "import()" method by itself to import a hash
array into the current namespace hash.
[% user = { id => 'lwall', name => 'Larry Wall' } %]
[% import(user) %]
[% id %]: [% name %] # lwall: Larry Wall
defined, exists
Returns a true or false value if an item in the hash denoted by the key
passed as an argument is defined or exists, respectively.
[% hash.defined('somekey') ? 'yes' : 'no' %]
[% hash.exists('somekey') ? 'yes' : 'no' %]
When called without any argument, "hash.defined" returns true if the
hash itself is defined (e.g. the same effect as "scalar.defined").
delete
Delete one or more items from the hash.
[% hash.delete('foo', 'bar') %]
size
Returns the number of key/value pairs in the hash.
item
Returns an item from the hash using a key passed as an argument.
[% hash.item('foo') %] # same as hash.foo
List Virtual Methods
first, last
Returns the first/last item in the list. The item is not removed from
the list.
[% results.first %] to [% results.last %]
If either is given a numeric argument "n", they return the first or
last "n" elements:
The first 5 results are [% results.first(5).join(", ") %].
size, max
Returns the size of a list (number of elements) and the maximum index
number (size - 1), respectively.
[% results.size %] search results matched your query
defined
Returns a true or false value if the item in the list denoted by the
argument is defined.
[% list.defined(3) ? 'yes' : 'no' %]
When called without any argument, "list.defined" returns true if the
list itself is defined (e.g. the same effect as "scalar.defined").
reverse
Returns the items of the list in reverse order.
[% FOREACH s IN scores.reverse %]
...
[% END %]
join
Joins the items in the list into a single string, using Perl's "join()"
function.
[% items.join(', ') %]
grep
Returns a list of the items in the list that match a regular expression
pattern.
[% FOREACH directory.files.grep('\.txt$') %]
...
[% END %]
sort, nsort
Returns the items in alpha ("sort") or numerical ("nsort") order.
[% library = books.sort %]
An argument can be provided to specify a search key. Where an item in
the list is a hash reference, the search key will be used to retrieve a
value from the hash which will then be used as the comparison value.
Where an item is an object which implements a method of that name, the
method will be called to return a comparison value.
[% library = books.sort('author') %]
In the example, the "books" list can contains hash references with an
"author" key or objects with an "author" method.
You can also specify multiple sort keys.
[% library = books.sort('author', 'title') %]
In this case the books will be sorted primarily by author. If two or
more books have authors with the same name then they will be sorted by
title.
unshift(item), push(item)
The "push()" method adds an item or items to the end of list.
[% mylist.push(foo) %]
[% mylist.push(foo, bar) %]
The "unshift()" method adds an item or items to the start of a list.
[% mylist.unshift(foo) %]
[% mylist.push(foo, bar) %]
shift, pop
Removes the first/last item from the list and returns it.
[% first = mylist.shift %]
[% last = mylist.pop %]
unique
Returns a list of the unique elements in a list, in the same order as
in the list itself.
[% mylist = [ 1, 2, 3, 2, 3, 4, 1, 4, 3, 4, 5 ] %]
[% numbers = mylist.unique %]
While this can be explicitly sorted, it is not required that the list
be sorted before the unique elements are pulled out (unlike the Unix
command line utility).
[% numbers = mylist.unique.sort %]
import
Appends the contents of one or more other lists to the end of the
current list.
[% one = [ 1 2 3 ];
two = [ 4 5 6 ];
three = [ 7 8 9 ];
one.import(two, three);
one.join(', ); # 1, 2, 3, 4, 5, 6, 7, 8, 9
%]
merge
Returns a list composed of zero or more other lists:
[% list_one = [ 1 2 3 ];
list_two = [ 4 5 6 ];
list_three = [ 7 8 9 ];
list_four = list_one.merge(list_two, list_three);
%]
The original lists are not modified.
slice(from, to)
Returns a slice of items in the list between the bounds passed as
arguments. If the second argument, "to", isn't specified, then it
defaults to the last item in the list. The original list is not
modified.
[% first_three = list.slice(0,2) %]
[% last_three = list.slice(-3, -1) %]
splice(offset, length, list)
Behaves just like Perl's "splice()" function allowing you to
selectively remove and/or replace elements in a list. It removes
"length" items from the list, starting at "offset" and replaces them
with the items in "list".
[% play_game = [ 'play', 'scrabble' ];
ping_pong = [ 'ping', 'pong' ];
redundant = play_game.splice(1, 1, ping_pong);
redundant.join; # scrabble
play_game.join; # play ping pong
%]
The method returns a list of the items removed by the splice. You can
use the "CALL" directive to ignore the output if you're not planning to
do anything with it.
[% CALL play_game.splice(1, 1, ping_pong) %]
As well as providing a reference to a list of replacement values, you
can pass in a list of items.
[% CALL list.splice(-1, 0, 'foo', 'bar') %]
Be careful about passing just one item in as a replacement value. If
it is a reference to a list then the contents of the list will be used.
If it's not a list, then it will be treated as a single value. You can
use square brackets around a single item if you need to be explicit:
[% # push a single item, an_item
CALL list.splice(-1, 0, an_item);
# push the items from another_list
CALL list.splice(-1, 0, another_list);
# push a reference to another_list
CALL list.splice(-1, 0, [ another_list ]);
%]
hash
Returns a reference to a hash array comprised of the elements in the
list. The even-numbered elements (0, 2, 4, etc) become the keys and
the odd-numbered elements (1, 3, 5, etc) the values.
[% list = ['pi', 3.14, 'e', 2.718] %]
[% hash = list.hash %]
[% hash.pi %] # 3.14
[% hash.e %] # 2.718
If a numerical argument is provided then the hash returned will have
keys generated for each item starting at the number specified.
[% list = ['beer', 'peanuts'] %]
[% hash = list.hash(1) %]
[% hash.1 %] # beer
[% hash.2 %] # peanuts
Automagic Promotion of Scalar to List for Virtual Methods
In addition to the scalar virtual methods listed in the previous
section, you can also call any list virtual method against a scalar.
The item will be automagically promoted to a single element list and
the appropriate list virtual method will be called.
One particular benefit of this comes when calling subroutines or object
methods that return a list of items, rather than the preferred
reference to a list of items. In this case, the Template Toolkit
automatically folds the items returned into a list.
The upshot is that you can continue to use existing Perl modules or
code that returns lists of items, without having to refactor it just to
keep the Template Toolkit happy (by returning references to list).
"Class::DBI" module is just one example of a particularly useful module
which returns values this way.
If only a single item is returned from a subroutine then the Template
Toolkit assumes it meant to return a single item (rather than a list of
1 item) and leaves it well alone, returning the single value as it is.
If you're executing a database query, for example, you might get 1 item
returned, or perhaps many items which are then folded into a list.
The "FOREACH" directive will happily accept either a list or a single
item which it will treat as a list. So it's safe to write directives
like this, where we assume that the "something" variable is bound to a
subroutine which may return one or more items:
[% FOREACH item IN something %]
...
[% END %]
The automagic promotion of scalars to single item lists means that you
can also use list virtual methods safely, even if you only get one item
returned. For example:
[% something.first %]
[% something.join %]
[% something.reverse.join(', ') %]
Note that this is very much a last-ditch behaviour. If the single item
return is an object with a "first" method, for example, then that will
be called, as expected, in preference to the list virtual method.
Defining Custom Virtual Methods
You can define your own virtual methods for scalars, lists and hash
arrays. The Template::Stash package variables $SCALAR_OPS, $LIST_OPS
and $HASH_OPS are references to hash arrays that define these virtual
methods. "HASH_OPS" and "LIST_OPS" methods are subroutines that accept
a hash/list reference as the first item. "SCALAR_OPS" are subroutines
that accept a scalar value as the first item. Any other arguments
specified when the method is called will be passed to the subroutine.
# load Template::Stash to make method tables visible
use Template::Stash;
# define list method to return new list of odd numbers only
$Template::Stash::LIST_OPS->{ odd } = sub {
my $list = shift;
return [ grep { $_ % 2 } @$list ];
};
Example template:
[% primes = [ 2, 3, 5, 7, 9 ] %]
[% primes.odd.join(', ') %] # 3, 5, 7, 9
TODO: document the define_vmethod() method which makes this even easier
perl v5.14.3 2012-02-07 Template::Manual::VMethods(3)
