CherryPy Caching

I just tried turning on CherryPy web caching, this is one of the few things which receives only very cursory treatment in Sylvain Hellegouarch's  excellent book, 'CherryPy Essentials'. I managed by incorporating the 

conf = {'/':{'tools.caching.on':True}}

line in my code, however I was dismayed to discover that once on, I couldn't form a request would not get the cached result. Neither 'Cache-Control:max-age=0' nor 'Pragma: no-cache' would do it. Looking into the code (I'm using v. 3.1.1), I found the caching.py tool and indeed saw it pays pretty much no attention to the http request headers except (bizarrely, I think) the 'Vary' header. I've inserted a few lines into caching.py to fix this and submitted a trac bug, so we'll see whether this changes. The code lines are reproduced here:

#some people still use Pragma : no-cache to demand a fresh resource

        pragma_no_cache=False

        pragma_header=request.headers.get('Pragma')

        if pragma_header:

            pragma_values=[header.strip() for header in pragma_header.split(',')]

            for this_value in pragma_values:

                if 'no-cache' in this_value:

                    pragma_no_cache=True

                    break

        #added by shaun, look at cache-control

        max_acceptable_age=MemoryCache.delay

        age_seconds=int(response.time - create_time)

        cache_control_header=request.headers.get('Cache-Control')

        if cache_control_header:

            #split string on commas to get the multiple words

            cache_control_values=[header.strip() for header in cache_control_header.split(',')]

            #look for max-age

            for this_value in cache_control_values:

                if ('max-age' in this_value) and ('=' in this_value):

                    age_pair=[age.strip() for age in this_value.split('=')]

                    if age_pair[1].isdigit():

                      max_acceptable_age=int(age_pair[1])

                    break

                  

        #return if the cache is older than the acceptable age

        if (age_seconds > max_acceptable_age) or pragma_no_cache:

            request.cached = False

            request.cacheable = True

            return False

            

        # Add the required Age header

        response.headers["Age"] = str(age_seconds)