# `Plushie.DSL.Buildable`
[🔗](https://github.com/plushie-ui/plushie-elixir/blob/v0.6.0/lib/plushie/dsl/buildable.ex#L1)

Behaviour for types that participate in the Plushie DSL block-form pattern.

Any struct whose values can be constructed via do-block declarations in
the DSL should implement this behaviour. The DSL block interpreter uses
these callbacks to:

- Validate field names at compile time (`__field_keys__/0`)
- Resolve nested struct types for recursive do-blocks (`__field_types__/0`)
- Construct the struct from keyword options at runtime (`from_opts/1`)

## Example

    defmodule MyType do
      @behaviour Plushie.DSL.Buildable

      defstruct [:name, :size]

      @impl true
      def from_opts(opts), do: %__MODULE__{name: opts[:name], size: opts[:size]}

      @impl true
      def __field_keys__, do: ~w(name size)a

      @impl true
      def __field_types__, do: %{}
    end

# `__field_keys__`

```elixir
@callback __field_keys__() :: [atom()]
```

Returns the list of valid field name atoms for this struct.

# `__field_types__`

```elixir
@callback __field_types__() :: %{required(atom()) => module()}
```

Returns a map of field names to struct modules for nested do-block resolution.

# `from_opts`

```elixir
@callback from_opts(opts :: keyword()) :: term()
```

Constructs the struct from a keyword list. Should validate unknown keys.

---

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