File cache for images
Fredrik Lundh
fredrik at pythonware.com
Mon Sep 20 02:04:34 EDT 2004
"me at here.there.nowhere" wrote:
> I'm looking for a way to cache some modified images as files (in a python
> program ofcourse). The scenario would look like this:
>
> getmodifiedimage(filename):
> is it in cache?
> is the cache up to date (not older than file)
> if not, modify filename and store in cache
> (keyed by filename + modification)
> return modified image
>
> I'm looking for prior-art before inventing it myself :)
I'm not sure what "modify filename" means, but a straightforward
solution is not that much longer than your pseudocode:
def getmodifiedimage(filename, cache={}):
try:
image, mtime = cache[filename]
if mtime < os.path.getmtime(filename):
raise KeyError
except KeyError:
image = open(filename, "rb").read() # or something
cache[filename] = image, os.path.getmtime(filename)
return image
</F>
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