Config sections don't cascade

[Martin Morrison]

When a plugin (bar) requests its config in a given context (room: foo), it should be returned the aggregate of the config from the following sections, in priority order (i.e. a given config item in an earlier section overrides the same config item in any later section):

plugin : bar : room : foo
room : foo : plugin : bar
plugin : bar : room : *
room : * : plugin : bar
plugin : bar
plugin : * : room : foo
room : foo : plugin : *
plugin : *

Similarly, if the core needs any configuration within a given context (room: foo), it should similarly use the following precedence:

room : foo
room : *
Setup

(this latter applies to, e.g. the "plugins" configuration item)

This should all be abstracted by the configparser module.

[Ben Hutchings (ben-hutchings)]

The configparser module does this to some extent, with the config:

[foo:bar]
var = 0
[foo|far:bar]
var = 2
[*:bar|baz]
var=7
[foo:*]
var = 4
[foo|far:*]
var=5
[foo:bar|baz]
var = 1
[*:bar]
var = 6
[foo|far:bar|baz]
var = 3
[*:*]
var=8

parser.get("foo", "bar", "var", return_all=True)
returns [0,1,2,3,4,5,6,7]

Some sections in usermanagement's read_config file could be changed from:
config = conf.get("room", name, key), which returns only the most relevant result
to something like

def combine(dct, new):
   dct.update(new)
   return dct

config = reduce(combine, reversed(conf.get(..., return_all=True)), {})

Which would combine results from all possibly relevant sections of the config file.

Alternatively there could be an extra kwarg in get that would do this.

[ChrisD (gingerchris)]

To add a bit more context:

This isn't specific to config items with the same name (as per Ben's comment above), this is also meant for items with different names e.g.:

[foo:bar]
exactly_specified = so
[foo|far:bar]
lvl1_or = long
[*:bar|baz]
lvl1_star_lvl2_or = and
[foo:*]
lvl2_star_wc = thanks
[foo|far:*]
lvl1_2_lvl2_star = for
[foo:bar|baz]
lvl2_or = all
[*:bar]
lvl1_star = the
[foo|far:bar|baz]
lvl1_lvl2_or = fish
[*:*]
everything = fish
exactly_specified = wrong

parser.get("foo","bar") should return a dict containing all the above config items and the value of exactly_sepcified should be "so" not "wrong".