close insightsengineering/coredev-tasks#502
#69

I tried to use `logger::log_messages()` (and similar functions for
warnings and errors) but I have encounter following problems:
- this is logging into the global logger namespace whereas we want
particular (package) namespace instead - created an issue
- I cloned logger locally and fixed / enhanced the above but then I
realized that the (global) message / warning / stop calls from the
outside of a package will also log to that package logger namespace. In
other words, these are _global_ handlers for all the warnings and not
only warnings created inside `teal` e.g.
```
r$> warning(1)
[WARN] 2024-01-26 15:58:17.0061 pid:83248 token:[] teal 1
Warning message:
1
```

Therefore I have decided to implement own register handlers mechanism. I
initially started doing this separately inside each package but then I
realised that it's not so DRY and decided to extend core `teal.logger`
functionality.

This is not a reprex as I modified `teal` and `teal.slice` namespaces in
a following way:
- added `register_handlers(<pkg>)` in both packages
- For debugging: added following definitions:
  - `teal.slice`:
    - `teal_s_message` calling `message()`
    - `teal_s_warning` calling `warning()`
    - `teal_s_stop` calling `stop()`
  - in `teal`:
    - `teal_message` calling `message()`
    - `teal_warning` calling `warning()`
    - `teal_stop` calling `stop()`
- `teal_message_nested` calling `teal_s_message()` (so as to simulate
`teal` calling `teal.slice`)
    - `teal_warning_nested` calling `teal_s_warning()`
    - `teal_stop_nested` calling `teal_s_stop()`

The outcome:

```
r$> devtools::load_all("teal.logger")
r$> devtools::load_all("teal.slice")
r$> devtools::load_all("teal")

r$> message(1)
1
r$> teal_message(1)
[INFO] 2024-01-26 15:57:40.8901 pid:83248 token:[] teal 1
1
r$> teal_s_message(1)
[INFO] 2024-01-26 15:57:42.1464 pid:83248 token:[] teal.slice 1
1
r$> teal_message_nested(1)
[INFO] 2024-01-26 15:57:50.9231 pid:83248 token:[] teal 1
[INFO] 2024-01-26 15:57:50.9257 pid:83248 token:[] teal.slice 1
1

r$> warning(2)
Warning message:
2 
r$> teal_s_warning(2)
[WARN] 2024-01-26 15:58:17.0061 pid:83248 token:[] teal.slice In ‘teal_s_warning(2)’: 2
Warning message:
In teal_s_warning(2) : 2
r$> teal_warning(2)
[WARN] 2024-01-26 15:58:18.4165 pid:83248 token:[] teal In ‘teal_warning(2)’: 2
Warning message:
In teal_warning(2) : 2
r$> teal_warning_nested(2)
[WARN] 2024-01-26 15:58:20.8666 pid:83248 token:[] teal In ‘teal.slice:::teal_s_warning(message)’: 2
[WARN] 2024-01-26 15:58:20.8685 pid:83248 token:[] teal.slice In ‘teal.slice:::teal_s_warning(message)’: 2
Warning message:
In teal.slice:::teal_s_warning(message) : 2

r$> stop(3)
Error: 3
r$> teal_s_stop(3)
[ERROR] 2024-01-26 15:58:32.9558 pid:83248 token:[] teal.slice In ‘teal_s_stop(3)’: 3
Error in teal_s_stop(3) : 3
r$> teal_stop(3)
[ERROR] 2024-01-26 15:58:33.5246 pid:83248 token:[] teal In ‘teal_stop(3)’: 3
Error in teal_stop(3) : 3
r$> teal_stop_nested(3)
[ERROR] 2024-01-26 15:58:34.0213 pid:83248 token:[] teal In ‘teal.slice:::teal_s_stop(message)’: 3
[ERROR] 2024-01-26 15:58:34.0226 pid:83248 token:[] teal.slice In ‘teal.slice:::teal_s_stop(message)’: 3
Error in teal.slice:::teal_s_stop(message) : 3
```

Interpretation (where "m/w/s" stands for "message / warning / stop"):
- global m/w/s is not impacted - we only capture m/w/s called from
inside the package
- capturing m/w/s in the appropriate logger namespace - see it as a part
of logger produced string - second last part
- the case of nested calls looks odd at the very first glance but I
think it's correct. Each (package) logger instance might have its own
log threshold, appender function, layout etc. It's expected to have
duplicated logs for each of the registered package namespace found on
the stack of calls. I'm interested in hearing your thoughts on this


PRs:

- [ ] insightsengineering/teal#1081
- [ ] insightsengineering/teal.goshawk#258
- [ ]
insightsengineering/teal.modules.clinical#1010
- [ ]
insightsengineering/teal.modules.general#628
- [ ]
insightsengineering/teal.modules.hermes#354
- [ ] insightsengineering/teal.osprey#252
- [ ] insightsengineering/teal.slice#551
- [ ] insightsengineering/teal.transform#175

(I'll keep them as draft as this is conflicting with release plans
because teal.logger would have to be released first)

TODO: tests - however I'm not yet sure how to make them "clean"

---------

Signed-off-by: Pawel Rucki <[email protected]>
Co-authored-by: Dawid Kałędkowski <[email protected]>