88 lines
4.0 KiB
Markdown
88 lines
4.0 KiB
Markdown
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# Operators
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## Basic
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Various basic operators can be applied directly to variable values.
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## Examples
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```smarty
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{$foo + 1}
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{$foo * $bar}
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{$foo->bar - $bar[1] * $baz->foo->bar() -3 * 7}
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{if ($foo + $bar.test % $baz * 134232 + 10 + $b + 10)}
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...
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{/if}
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{$foo = $foo + $bar}
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```
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> **Note**
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>
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> Although Smarty can handle some very complex expressions and syntax,
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> it is a good rule of thumb to keep the template syntax minimal and
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> focused on presentation. If you find your template syntax getting too
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> complex, it may be a good idea to move the bits that do not deal
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> explicitly with presentation to PHP by way of plugins or modifiers.
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## List
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The following is a list of recognized operators, which must be
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separated from surrounding elements by spaces. Note that items listed in
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\[brackets\] are optional. PHP equivalents are shown where applicable.
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| Operator | Alternates | Syntax Example | Meaning | PHP Equivalent |
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|--------------------|------------|----------------------|--------------------------------|--------------------|
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| == | eq | $a eq $b | equals | == |
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| != | ne, neq | $a neq $b | not equals | != |
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| > | gt | $a gt $b | greater than | > |
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| < | lt | $a lt $b | less than | < |
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| >= | gte, ge | $a ge $b | greater than or equal | >= |
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| <= | lte, le | $a le $b | less than or equal | <= |
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| === | | $a === 0 | check for identity | === |
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| ! | not | not $a | negation (unary) | ! |
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| % | mod | $a mod $b | modulo | % |
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| is \[not\] div by | | $a is not div by 4 | divisible by | $a % $b == 0 |
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| is \[not\] even | | $a is not even | \[not\] an even number (unary) | $a % 2 == 0 |
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| is \[not\] even by | | $a is not even by $b | grouping level \[not\] even | ($a / $b) % 2 == 0 |
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| is \[not\] odd | | $a is not odd | \[not\] an odd number (unary) | $a % 2 != 0 |
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| is \[not\] odd by | | $a is not odd by $b | \[not\] an odd grouping | ($a / $b) % 2 != 0 |
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| is in | | $a is in $b | exists in array | in_array($a, $b) |
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| is \[not\] in | | $a is not in $b | does not exist in array | !in_array($a, $b) |
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## Ternary
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You can use the `?:` (or ternary) operator to test one expression and present the value
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of the second or third expression, based on the result of the test.
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In other words:
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```smarty
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{$test ? "OK" : "FAIL"}
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```
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will result in OK if `$test` is set to true, and in FAIL otherwise.
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There is also a shorthand `?:` operator:
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```smarty
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{$myVar ?: "empty"}
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```
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will result in 'empty' if `$myVar` is not set or set to something that evaluates to false, such as an empty string.
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If `$myVar` is set to something that evaluates to true, the value of `$myVar` is returned. So, the following will
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return 'hello':
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```smarty
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{$myVar="hello"}
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{$myVar ?: "empty"}
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```
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## Testing for null
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If "something that evaluates to false" is to broad a test for you, you can use the `??` (or null coalescing) operator
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to trigger only if the tested value is undefined or set to null.
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```smarty
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{$myVar ?? "empty"}
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```
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will result in 'empty' if `$myVar` is not set or set to null.
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If `$myVar` is set to something that evaluates to anything else, the value of `$myVar` is returned. So, the following will
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return an empty string (''):
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```smarty
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{$myVar=""}
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{$myVar ?: "this is not shown"}
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```
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