1.2.1059. Scalar Or Object Property

Property shouldn’t use both object and scalar syntaxes. When a property may be an object, it is recommended to implement the Null Object pattern : instead of checking if the property is scalar, make it always object.

<?php

class x {
    public $display = 'echo';

    function foo($string) {
        if (is_string($this->display)) {
            echo $this->string;
        } elseif ($this->display instanceof myDisplayInterface) {
            $display->display();
        } else {
            print "Error when displaying\n";
        }
    }
}

interface myDisplayInterface {
    public function display($string); // does the display in its own way
}

class nullDisplay implements myDisplayInterface {
    // implements myDisplayInterface but does nothing
    public function display($string) {}
}

class x2 {
    public $display = null;

    public function __construct() {
        $this->display = new nullDisplay();
    }

    function foo($string) {
        // Keep the check, as $display is public, and may get wrong values
        if ($this->display instanceof myDisplayInterface) {
            $display->display();
        } else {
            print "Error when displaying\n";
        }
    }
}

// Simple class for echo
class echoDisplay implements myDisplayInterface {
    // implements myDisplayInterface but does nothing
    public function display($string) {
        echo $string;
    }
}

?>

See also Null Object Pattern and The Null Object Pattern.

1.2.1059.1. Suggestions

• Only use one type of syntax with your properties.

1.2.1059.2. Specs

Short name	Classes/ScalarOrObjectProperty
Rulesets	All, Analyze
Exakat since	0.12.3
PHP Version	All
Severity	Minor
Time To Fix	Slow (1 hour)
Precision	High
Features	object, scalar-typehint
Examples	SugarCrm
Available in	Entreprise Edition, Exakat Cloud