"not something is defined" vs "something is not defined"

Question

Is there a difference between the notation not something is defined vs something is not defined. To me it looks like the same behavior but maybe I miss something here.

Answer 1

No, the compiled result is the same. Guess it's just a preference

Snippet

{% if not something is defined %}

{% endif %}

-----------------------------------------

{% if something is not defined %}

{% endif %}

Compiled result

    protected function doDisplay(array $context, array $blocks = [])
    {
        $macros = $this->macros;
        // line 1
        if ( !array_key_exists("something", $context)) {
            // line 2
            echo "
";
        }
        // line 4
        echo "
-----------------------------------------

";
        // line 7
        if ( !array_key_exists("something", $context)) {
            // line 8
            echo "
";
        }
    }

demo