Syntax
Syntax refers to the set of rules that defines the structure of valid PHP code.
For example, there is the object syntax, around the -> and :: operators, and the array syntax, around [index] operator.
Syntax must be lintable for a PHP script to be executable. Otherwise, it creates a syntax error. Yet, a lintable syntax does not always mean the code is executable: it may yield an execution error. It is not always obvious which syntax is not executable.
<?php
A = B C; // syntax error, 'C' is not valid.
clone 1; // not a syntax error
$array = ['a' => 1, 'b' => 2, 'c' => 3];
echo $array['a']; // 1
$object = (object) $array;
echo $object->a; // 1
echo $object['a']; // no syntax error, error at execution
//valid syntax
function trumpet($trunk) {
print $trunk;
}
//valid call
trumpet(3);
//invalid call
trumpet([]);
?>