each_line

/*
 *  call-seq:
 *     ios.each(sep_string=$/)      {|line| block }  => ios
 *     ios.each_line(sep_string=$/) {|line| block }  => ios
 *  
 *  Executes the block for every line in <em>ios</em>, where lines are
 *  separated by <i>sep_string</i>. <em>ios</em> must be opened for
 *  reading or an <code>IOError</code> will be raised.
 *     
 *     f = File.new("testfile")
 *     f.each {|line| puts "#{f.lineno}: #{line}" }
 *     
 *  <em>produces:</em>
 *     
 *     1: This is line one
 *     2: This is line two
 *     3: This is line three
 *     4: And so on...
 */

static VALUE
rb_io_each_line(argc, argv, io)
    int argc;
    VALUE *argv;
    VALUE io;
{
    VALUE str;
    VALUE rs;

    RETURN_ENUMERATOR(io, argc, argv);
    if (argc == 0) {
        rs = rb_rs;
    }
    else {
        rb_scan_args(argc, argv, "1", &rs);
        if (!NIL_P(rs)) StringValue(rs);
    }
    while (!NIL_P(str = rb_io_getline(rs, io))) {
        rb_yield(str);
    }
    return io;
}