# `Mob.AppConfig`
[🔗](https://github.com/genericjam/mob/blob/master/lib/mob/app_config.ex#L1)

Puts the project's `config/*.exs` into the application environment on device.

A Mob app boots from a custom BEAM entry (`<app>:start()`), not a release,
so nothing reads `config/config.exs` on the phone and `Application.get_env/2`
returns `nil` for everything that isn't `compile_env`. mob_dev closes that
gap at build time: it evaluates `config/config.exs` (and `config/runtime.exs`,
**on the build host**) for the build's Mix env and target, and ships the
result as a generated `:mob_app_config` module next to the app's own BEAMs.
`Mob.App.start/0` calls `load/0` before anything else reads the environment.

The values are put with `persistent: true`, so a later `Application.load/1`
of the same app (starting a plugin's OTP application loads it) does not
replace them with the defaults in its `.app` file.

## `:logger`

The `:logger` application is already running when the config arrives (the
device entry starts it before `Mob.App.start/0`), so its settings that
are read once at startup can't take effect. Applied:

  * `:level`, through `Logger.configure/1`, so the running Logger's primary
    level changes. An invalid level is logged and skipped.
  * `:translator_inspect_opts`, which Logger reads from the environment
    each time it's used.

Not applied, because Logger reads them only when it starts:
`:default_handler`, `:default_formatter`, `:handle_otp_reports`,
`:handle_sasl_reports`, `:translators`, `:backends`, and `:truncate` /
`:utc_log` for the default handler's formatter. The `:compile_time_*` keys
are compile-time only. Logger output on device goes through
`Mob.NativeLogger` anyway.

# `load`

```elixir
@spec load(module()) :: :ok | :none | {:error, term()}
```

Applies the generated config module, if there is one.

Returns `:ok` once applied, `:none` when the module isn't present (an app
built by an older mob_dev, or a host test), and `{:error, reason}` when it
can't be applied. Never raises: a broken config must not stop the app from
booting, so the failure is logged and the app runs with what it has.

---

*Consult [api-reference.md](api-reference.md) for complete listing*