get attribute from class not working php 7

php variables reference global-variables php-7

PHP Snippet 1:

$baz = $this->table->{$quux['field']}

PHP Snippet 2:

$baz = ($this->table->$quux)['field']

PHP Snippet 3:

$baz = $this->table->{$quux['field']}

PHP Snippet 4:

`Expression: $foo->$bar['baz']  PHP 5: $foo->{$bar['baz']} PHP7: ($foo->$bar)['baz']`