Allow pickling simple instances of caches.

[ncalexan]

This is not particularly robust, but it handles (and tests) the simplest
examples. In general, pickle does not handle lambda functions, so this
is about the best that can be done. It's worth noting that this uses
a non-default pickle protocol: the regular one fails due to slots
with no getstate implementation. This non-default protocol is
specified with dumps(cache, -1): the -1 means "latest".

For a more robust pickling solution, try the dill module.

[tkem]

Thanks, I wasn't aware of that, since I never used pickle myself.
Now, before I look into this any further, the unit tests (even more thanks for providing those) seem to fail on Python 3; could you please have a look what's wrong there?

[tkem]

Please correct me if I'm wrong, but AFAICS, for the Cache base class, reverting to v1.0.0 with a non-lambda one function may also handle this for the simple case.

[tkem]

As for pickling the Cache base class, please also take a look at 7bc51c6.

[tkem]

@ncalexan: you still there?

[ncalexan]

@tkmem: thanks for pushing this over the line.

On Thu, Jun 18, 2015 at 10:27 AM, Thomas Kemmer notifications@github.com
wrote:

Closed #40 #40 via 385ace8
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[tkem]

You're welcome ;-) Hope you don't mind that I didn't use your initial implementation, but this matched some refactorings regarding getsizeof/missing and the excessive use of lambdas I wanted to do anyway... And so I learned a little about pickling along the way, too.

[ncalexan]

On Thu, Jun 18, 2015 at 11:46 AM, Thomas Kemmer notifications@github.com
wrote:

You're welcome ;-) Hope you don't mind that I didn't use your initial
implementation, but this matched some refactorings regarding getsizeof/
missing and the excessive use of lambdas I wanted to do anyway... And so
I learned a little about pickling along the way, too.

Not at all. I ended up using pylru since it was easier to pickle, so I'm
just glad a patch landed for next time.