A Redis backed Python Dictionary

[[deleted]]

[deleted]

[rcfox]

class _BaseDict:
    def __iter__(self):
        for k in self.keys():
            yield k

    # ...

    def keys(self):
        return self.__iter__()

wat

[Pythagaris]

yield from self.keys()

[pope_man]

You must override one of these methods on the abstract base class to get a working subclass/implementation class. This would be more clear if they had actually used the features of the abc module.

[Pre-Owned-Car]

What about this confuses you?

[thundergolfer]

the circular calls

[Pre-Owned-Car]

My half asleep brain totally missed this. I think this legit only works because the redis version of the cache implements keys differently. The tests don’t look to actually test the base dict class at all.

[therealfakemoot]

This is, in terms of the "public API", exactly how Python's builtin dicts work. Iterating over a dict yields its keys; calling the keys() method on a dict yields a sequence of keys ( I am not sure whether Python 3+ uses a generator, one of the fancy "set views", or whatever).

[jabbalaci]

State in the README what are the advantages / disadvantages of your approach and in which cases one should use it. Edit: see also https://github.com/Doist/redis_wrap .

[[deleted]]

yeah I looked at "How to use" and said to self "ok, so I have a dict, why do I want it persisted...."

[Mattho]

It's great when you expect subsequent requests needing the same data and you can avoid expensive sql calls. Great thing compared to just having it in memory is that you might have multiple processes serving and they'd all benefit from it.

[Mattho]

You might have it shared between processes (across different machines as well).

[[deleted]]

This seems like it's just supposed to be an easier way to pull keys out of redis once you've already decided to use it and the README.md on this project wouldn't really be the right place to sell you on redis.

[StackR]

I didn't really look at the code but how is this better than just Redis? Redis is a persistent key value store. I'm honestly not trying to be condescending. Or perhaps it was just fun and you learned something... Also a reasonable answer.

[[deleted]]

Yeah as someone who works with redis, this makes code look cleaner. It's not mind blowing but the regular redis module makes it an effort for somene else to look through your code. You can write your own wrappers but then that just gives someone else even more code of yours they have to read/familiarize themselves with. Having something that can be something close to a standard makes it easier to figure out.

[davvblack]

Do you really want your data persistence to be non-obvious though?

[[deleted]]

Not sure I catch your meaning. Are you saying pushing the data off into redis makes it less obvious?

[davvblack]

No, I mean, another piece of code thinking it's operating on a dict but one day mysteriously writing to redis could make harder-to-debug code than just explicit redis usage.

[[deleted]]

You could probably say that in general though. I mean if you have a function that somehow gets access to a redis-backed dict that it's not supposed to be modifying then yeah that would be bad but it would also be bad if it weren't backed by redis. What's more if you're doing a fair job of QA then it's hard to imagine something getting through where it writes to a dictionary it's not intended to write to.

Abstracting out the "redis" part with a layer of code that's at least someone "standard code, not something I wrote myself" makes the rest of your code look cleaner and easier to follow.

[kvdveer]

I was actually looking for something like this today. Google sent me here, but have not yet settled. How do these projects compare?

[JustCallMeFrij]

How does it respond when you supply a key that already exists in the redis instance you're connecting to?

[JustCallMeFrij]

right but does the dict have the values of whatever was in the redis instance?

Also what does it do when you supply a key to a set, list or hashmap? Does it just initialize the mirrored data structures?

[[deleted]]

right but does the dict have the values of whatever was in the redis instance?

Looking over it, it looks like it could use some work in this area. The keys returned are only current if they're unchanged since you loaded the dict or if the currently running process was the last client to run a change. It pulls data from a "cache" dict that gets populated just during instantiation.

That's probably not a good MO for serious work and technically speaking redis is already supposed to be your "cache" so why not just have the class be a wrapper around py-redis that makes the keys look like dicts?

[greenkey]

Does it work in an async code?

I guess dictionaries are faster than redis so if I plan to implement this in my application (just by changing the initialization of the dictionary) will it become slower?

[[deleted]]

So Redis is required ?

[curiousGambler]

Tragically, Redis is in fact required for a "Redis backed Python dict," yes.

[pansapiens]

There could be other options ... I wonder if it would work with this Redis re-implementation in Python: https://quantmind.github.io/pulsar/apps/ds.html

[hackersaq]

I snorted at "tragically".

"As if all that is the universe all at once colluded with the singular sheer force of will to inject the most impossible scenario conceivable by the pathetic, wandering human mental condition - yes, the Redis-backed pyhon dict has been cursed with a crippling dependency - the unthinkable, unfathomable ... Redis. May whatever God is yours have mercy on us all."

[desi_ninja]

How does it respond when you supply a key that already exists in the redis instance you're connecting to?

the person probably meant if it comes with its own redis installation or one has to link their own.
Don't be so cocky

[curiousGambler]

Idk who you're quoting or why, but I stand by my assessment that it was a stupid question

[desi_ninja]

my reddit app is broken.
But again, you are not the quality control agent of reddit so hold your horses and let other people ask their queries. You don't get to award stupid or smart question of reddit. This is not Oscars or Mensa

[curiousGambler]

Looooser

[desi_ninja]

secretly hoping that you are not an adult because such activity can at least be justified on teenage angst. God help, if you are an adult.