[Feature] Allow TTL to be zero

[eatnumber1]

It would be convenient if bkt supported BKT_TTL=0 (and when zero, did not cache anything). That way, I can write scripts where bkt is opt-in by adding the line export BKT_TTL=${BKT_TTL:-0} to my script, then using bkt throughout.

Today, it's an assertion error.

[dimo414]

I understand the motivation but I don't love using BKT_TTL as the mechanism. Notably, it wouldn't work for any calls that pass --ttl on the command line so as a user you can't be certain the script is fully disabling caching without reading the code.

Personally, I'd abstract away bkt and BKT_TTL and have the caller configure caching using args / flags / env vars that the script defines instead. You could check for --disable-caching or whatever and define a noop bkt function.

I realize this is a bit more boilerplate for the script author, so I could possibly be convinced of the value of a BKT_NOOP / --noop argument, but I don't think the TTL is the right mechanism to use as a proxy for this noop behavior. It's possible I'd even make TTL an optional flag in the future (#27) which would likely be at odds with this behavior.