public static function setVaryByHeader($actionName, $value) {
        if (!self::canCache($actionName)) { return; }
        self::$settings[$actionName]['varyByHeader'] = $value;
    }
public static function setVaryByHeader($actionName, $value) {
        if (!self::canCache($actionName)) { return; }
        self::$settings[$actionName]['varyByHeader'] = $value;
    }
public static function setVaryByHeader ( $ actionName , $ value ) { if ( ! self :: canCache ( $ actionName ) ) { return ; } self :: $ settings [ $ actionName ] [ 'varyByHeader' ] = $ value ; }
Sets the vary-by-header value.

@param string $actionName Action name.
@param string $value A semicolon-separated list of HTTP headers that are used to vary the output cache.

@return void
Sets the vary - by - header value .