Cache Manager - separate concern

[FastNinja]

Two thoughts crossed my mind:

1. I really couldn't find a place where you eliminate/delete images from cache. it looks like it will grow infinitely.
2. I actually need similar caching capabilities for other assets- like documents and even maybe JSON data

These leads me to think that your Cache Manager actually will be helpful as a separate package.
Caching data on a mobile phone is very common practice/concern so I can see it is much more widely used as CachedNetworkImageProvider

Proposal: extract Cache Manager as a separate package. Add ability to eliminate entities. Make it generic so it is not coupled with HttpHeaders or any other concerns.

[renefloor]

About your points

1. Cleaning the cache is indeed my number 1 priority at the moment, but I was thinking about how best to do that. For now I only used this cachemanager for images that I use all the time and that almost never change. This is also the reason that I didn't yet publish it as a separate package.

2. Like we already discussed in Throws exception when content-type is not image #4 it is very well possible to eliminate the header for content type. I will do that for sure when I publish it separately. About HttpHeaders in general, I will keep the check for 'cache-control', but now I download the file every time when it has no information about that, I can change that to never download again or set that to a default length.

[FastNinja]

@renefloor I think my point was nothing to do with header but more to the point that CacheManager sounds like pretty useful package. any data/documents can be cached.
Elimination strategy can be configured or passed as a custom class:

1. for example cache manager can have a size of only 2000 entities and it will remove the most not used one, or the oldest etc..

[renefloor]

Yes I understand, I also think it is very useful as a separate package. Using a count is a good idea. I will probably do that in combination with a maximum age. I will make them both configurable by the user, but I think a default of 2000 items is a bit much.

[renefloor]

I just made the needed changes in separate feature branch. Would like to hear your opinion.
https://github.com/renefloor/flutter_cached_network_image/tree/feature/generic_cache_manager.
I made one commit for the cleaning of the cache: e1711d0
And one to remove the forced check of the image content type: 2d0343c

[FastNinja]

@renefloor looks good, but can be even better.
I created a PR so it easier to discuss
#6

[renefloor]

@FastNinja I just moved the cache manager to its own repo and released a first version of it.
https://github.com/renefloor/flutter_cache_manager

Let's move the discussion there. I already refactored some bit and opened an issue for error reporting. I don't have much time coming period, so if you have any breaking issues, please make a pull request for it.