Values and literals #

The expression parser (lib/eztemplate/classes/eztemplateelementparser.php) knows six kinds of literal values. This page lists them with the exact rules of the parser and shows each on a development installation. get_type (from eZTemplateTypeOperator) prints the PHP type of a value, so it is used here to show what a literal becomes.

Contents #

1. Strings
2. Numbers
3. Booleans
4. Arrays and hashes
5. Identifiers
6. Null
7. Truthiness
8. Related pages

Strings #

A string is written in single or double quotes. The two are the same: neither interpolates variables, so "Hello $name" prints the dollar sign and the name literally. Join strings with concat.

unescapeCharacters() knows these escapes, in both kinds of quotes:

Inside a tag, a } in a string must be written \}, or the tag ends there (see Lexical structure).

{def $name = 'World'}
[{'Hello $name'}] [{"Hello $name"}] [{concat( 'Hello ', $name )}]
[{'It\'s'}] [{"say \"hi\""}] [{'tab:\t:'}] [{'back\\slash'}] [{'unknown \q stays'}]
[{'line one\nline two'}]

Output:

[Hello $name] [Hello $name] [Hello World]
[It's] [say "hi"] [tab:	:] [back\slash] [unknown \q stays]
[line one
line two]

Numbers #

A number is a run of digits with an optional leading - and at most one . followed by digits. Without a dot it is an integer, with one it is a float (numericEndPos()). A dot must be followed by a digit: 1. is the number 1 followed by a parser error (shown at the end of this section). Floats are printed by PHP, so 1.50 prints 1.5.

Strings from content or requests stay strings until an operator converts them; int and float do it explicitly. div returns an integer when the division has no remainder and a float otherwise.

[{42}] [{-7}] [{3.14}] [{0.5}] [{1.50}]
[{42|get_type}] [{3.14|get_type}] [{'42'|get_type}] [{'42'|int|get_type}]
[{10|div( 4 )}] [{10|div( 5 )|get_type}]

Output:

[42] [-7] [3.14] [0.5] [1.5]
[integer] [double] [string[2]] [integer]
[2.5] [integer]

A dot without a digit after it:

[{1.|get_type}]

Output:

[1]

Logged by the template engine:

ERROR : parser error @ tl-values/07-number-dot.tpl:1[2]
Extra characters found in expression, they will be ignored.
.|get_type' (1)

Booleans #

There is no true or false keyword: true() and false() are operators of eZTemplateLogicOperator that return the PHP booleans. Printed, true becomes 1 and false the empty string, as in PHP.

[{true()}] [{false()}] [{true()|get_type}] [{false()|get_type}]
[{if 0}0 is true{else}0 is false{/if}] [{if '0'}'0' is true{else}'0' is false{/if}] [{if ''}empty is true{else}empty is false{/if}] [{if array()}empty array is true{else}empty array is false{/if}]

Output:

[1] [] [boolean[true]] [boolean[false]]
[0 is false] ['0' is false] [empty is false] [empty array is false]

Arrays and hashes #

array( ... ) builds a list with keys 0, 1, 2 and hash( key, value, ... ) a map from pairs. Both come from eZTemplateArrayOperator, so they are operators like any other and can be nested, piped and passed as parameters. Elements are read with a dot or with brackets: $list.1, $map.red, $deep['count'].

{def $list = array( 'a', 'b', 'c' )
     $map  = hash( 'red', '#f00', 'green', '#0f0' )
     $deep = hash( 'sizes', array( 'S', 'M', 'L' ), 'count', 3 )}
[{$list|count}] [{$list.1}] [{$list|implode( '-' )}]
[{$map.red}] {foreach $map as $k => $v}[{$k}={$v}]{/foreach}
[{$deep.sizes.2}] [{$deep['count']}]
[{array()|count}] [{$list|get_type}] [{$map|get_type}]

Output:

[3] [b] [a-b-c]
[#f00] [red=#f00][green=#0f0][L] [3]
[0] [array[3]] [array[2]]

get_type adds the number of elements for arrays and the length for strings, which makes it useful when debugging.

Identifiers #

A bare word that is not followed by ( is an identifier, and its value is the word itself. Some operators and functions use identifiers where other languages would use quoted keywords, for example attribute( show, 2 ) or sequence array( odd, even ):

[{1|choose( zero, one, two )}] [{array( red, green )|implode( '+' )}]

Output:

[one] [red+green]

The characters allowed in identifiers and variable names are letters, digits, _ and - (identifierEndPosition()). A dash is part of the name, so $my-var is one variable, not a subtraction.

Null #

There is no null literal. null exists, but it is a test from eZTemplateLogicOperator that is true when its input is null, not a value. Null values arrive from PHP, for example from a fetch that finds nothing; test them with is_null or is_set, and replace a missing variable with first_set:

{def $empty = fetch( 'content', 'node', hash( 'node_id', 999999999 ) )}
[{$empty|get_type}] [{if $empty|is_null}is null{/if}] [{if is_set( $empty )}is set{else}not set{/if}] [{first_set( $missing, 'default' )}]

Output:

[null] [is null] [not set] [default]

Truthiness #

Conditions use PHP truthiness. 0, '0', the empty string, an empty array, false() and null are false; everything else, including an array that holds a 0, is true. The values tested in this loop are 0, 1, '', 'x', '0', array(), array( 0 ), false() and true():

{foreach array( 0, 1, '', 'x', '0', array(), array( 0 ), false(), true() ) as $v}[{if $v}T{else}F{/if}]{/foreach}

Output:

[F][T][F][T][F][F][T][F][T]

Related pages #

• Previous: Lexical structure
• Next: Variables in depth
• TPL syntax basics
• Array operators
• The type operators
• Free documentation: this page is free to copy, translate and improve under the GNU FDL 1.3.