Alternative to query_posts for main loop? [duplicate]

When I added the drawbacks to the Codex, I was mainly thinking of using the ‘request’ filter as an alternative to query_posts().

That filter is only run for the main query, so that solves the problem with ‘pre_get_posts’, which fires for every query.

The downside is that you don’t have access to query flags like is_single() etc.

Here’s one way you could get access to them, without actually doing the SQL queries:

function alter_the_query( $request ) {
    $dummy_query = new WP_Query();  // the query isn't run if we don't pass any query vars
    $dummy_query->parse_query( $request );

    // this is the actual manipulation; do whatever you need here
    if ( $dummy_query->is_home() )
        $request['category_name'] = 'news';

    return $request;
}
add_filter( 'request', 'alter_the_query' );