Decide preferred method for configurations

[danibishop]

Current version uses a dictionary for datasource configuration and some classes for specific configurations (cache config and per-query config).

Default behavior is enough for basic access but we need to discuss how do we want it to look when specific cases appear. Is the current system a good policy? Do we want something more relaxed (i.e. dictionaries)? More restrictive (i.e. classes)? Parameter based (i.e. **kwargs)?

[josemazo]

And what about regular paramters for common configuration, like cache and write_query, and use a dict like extra_params?

[danibishop]

As discussed on 2019.01.30, usual parameters will be passed directly in each method parameters and the rest (less common) will be wrapped in dictionaries.

[danibishop]

I created a nice class for transparent configuration management. Now, we have a common get_config(key) for caches, datasorces or any class in the future.

It has a default mechanism; when you create a new datasource class (sqlite, for example), you can define a _default_configuration class attribute. The keys there are interpreted as the only ones that can be used and, if no specific one is overwritten, the default value is used.