# `GeoGenius.Context`
[🔗](https://github.com/agoodway/geo_genius/blob/main/lib/geo_genius/context.ex#L1)

Runtime dependencies for one GeoGenius operation.

# `t`

```elixir
@type t() :: %GeoGenius.Context{
  cache: module() | nil,
  command: module() | nil,
  downloader: module() | nil,
  notifier: module() | nil,
  prefix: String.t(),
  repo: module(),
  runner: module() | nil,
  store: module()
}
```

# `adapter`

```elixir
@spec adapter(t(), atom()) :: module()
```

The module serving one adapter role for this operation.

A context built through `new/1` carries its adapters. A context assembled as
a struct literal carries nil, and falls back to the same resolution `new/1`
used, so a caller that built one by hand still gets a working adapter rather
than a `nil` module and an `UndefinedFunctionError` several phases in.

`:runner` always routes through `Runner.configured/1`, even when this
context already carries an explicit module for it: that is the only place
an explicit runner is validated -- checked for `Code.ensure_loaded?/1` and
every `GeoGenius.Runner` callback -- and a lookup that returned early on a
non-nil field would skip that check on the one path a host actually calls,
`Context.new(runner: SomeModule) |> Context.adapter(:runner)`. The other
adapters have no such validation step, so they keep the cheap early return:
a context already carrying one never spends a second lookup on it.

# `new`

```elixir
@spec new(keyword()) :: t()
```

Builds a context from explicit options over package configuration.

The application environment describes exactly one host. A VM serving several
hosts passes `:repo` and `:prefix` on every call instead.

`:runner` carries only what `opts` explicitly gave -- never `nil` coalesced
against `config :geo_genius, :runner` here, and never validated here. Both
of those happen once, in `Runner.configured/1`, the only place they need to
live: `adapter/2` routes every `:runner` lookup through it below, whether
this context ends up carrying an explicit module or `nil`.

---

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