public function appendFilter(string $filtername, int $read_write, $params = null)
    {
        $res = @stream_filter_append($this->stream, $filtername, $read_write, $params);
        if (is_resource($res)) {
            $this->filters[$filtername][] = $res;
            return;
        }

        throw new Exception(sprintf('unable to locate filter `%s`', $filtername));
    }
public function appendFilter(string $filtername, int $read_write, $params = null)
    {
        $res = @stream_filter_append($this->stream, $filtername, $read_write, $params);
        if (is_resource($res)) {
            $this->filters[$filtername][] = $res;
            return;
        }

        throw new Exception(sprintf('unable to locate filter `%s`', $filtername));
    }
public function appendFilter ( string $ filtername , int $ read_write , $ params = null ) { $ res = @ stream_filter_append ( $ this -> stream , $ filtername , $ read_write , $ params ) ; if ( is_resource ( $ res ) ) { $ this -> filters [ $ filtername ] [ ] = $ res ; return ; } throw new Exception ( sprintf ( 'unable to locate filter `%s`' , $ filtername ) ) ; }
append a filter.

@see http://php.net/manual/en/function.stream-filter-append.php

@param  null|mixed $params
@throws Exception  if the filter can not be appended
append a filter .