wordlimit.py

def limit(s, max):
    """ Limit string s to x characters respecting space boundaries

    >>> limit('cat dog', 3);
    'cat'
    >>> limit('cat', 3);
    'cat'
    >>> limit('cat ', 4);
    'cat'
    >>> limit('cat dog', 5);
    'cat'
    >>> limit('cat dog bird', 10);
    'cat dog'
    >>> limit('cat', 9);
    'cat'
    """
    
    if len(s) <= max:
        return s
    for i in range(max-1, 0, -1):
        if s[i] == ' ':
            max = i
            break
    # max b/c slice is exclusive at the end
    return s[:max]