Drafter.Widget.Callback (drafter v0.3.2)

Wraps atom event names or functions into closures for widget callback wiring.

wrap_0/1, wrap_1/1, and wrap_2/1 each accept nil, a bare function of the matching arity, or an atom name. When given an atom, the returned closure dispatches the event to the app loop as {:app_event, name, data} when no modal screen is active, or as {:tui_event, {:app_callback, name, data}} when a modal is on top.

Anything that is neither nil nor a function of the matching arity is treated as a name, including a function of the wrong arity.

wrap_0/1, wrap_1/1 and wrap_2/1 capture self() at wrap time, so they must be called from the process that runs the app loop — normally inside a widget's from_component_opts/2. wrap_1_with_pid/2 takes the target pid explicitly for callers that cannot guarantee that.

A dispatching closure returns the message it sent, not the app's reply, because send/2 returns its own message. Widgets that turn a callback result into an action therefore only ever see an {:app_callback, _, _} tuple when the caller supplied a plain function that builds one.

Summary

Functions

wrap_0(f)

Wraps a zero-arity callback option.

wrap_1(f)

Wraps a one-arity callback option.

wrap_1_with_pid(f, session_pid)

Like wrap_1/1, but dispatches to session_pid instead of to self().

wrap_2(f)

Wraps a two-arity callback option.

Functions

wrap_0(f)

@spec wrap_0(nil | (-> any()) | atom()) :: (-> any()) | nil

Wraps a zero-arity callback option.

Returns nil for nil, the function itself for a function of arity 0, and otherwise a new zero-arity closure that dispatches name with nil data to self().

iex> Drafter.Widget.Callback.wrap_0(nil)
nil

iex> f = fn -> :clicked end
iex> Drafter.Widget.Callback.wrap_0(f) == f
true

iex> is_function(Drafter.Widget.Callback.wrap_0(:clicked), 0)
true

wrap_1(f)

@spec wrap_1(nil | (term() -> any()) | atom()) :: (term() -> any()) | nil

Wraps a one-arity callback option.

Returns nil for nil, the function itself for a function of arity 1, and otherwise a new one-arity closure that dispatches name with its argument as the data to self().

iex> Drafter.Widget.Callback.wrap_1(nil)
nil

iex> is_function(Drafter.Widget.Callback.wrap_1(:changed), 1)
true

wrap_1_with_pid(f, session_pid)

@spec wrap_1_with_pid(nil | (term() -> any()) | atom(), pid()) ::
  (term() -> any()) | nil

Like wrap_1/1, but dispatches to session_pid instead of to self().

Use this when the wrapping happens outside the process that runs the app loop.

iex> Drafter.Widget.Callback.wrap_1_with_pid(nil, self())
nil

iex> is_function(Drafter.Widget.Callback.wrap_1_with_pid(:changed, self()), 1)
true

wrap_2(f)

@spec wrap_2(nil | (term(), term() -> any()) | atom()) ::
  (term(), term() -> any()) | nil

Wraps a two-arity callback option.

Returns nil for nil, the function itself for a function of arity 2, and otherwise a new two-arity closure that dispatches name with its two arguments packed into the tuple {a, b} as the data.

iex> Drafter.Widget.Callback.wrap_2(nil)
nil

iex> is_function(Drafter.Widget.Callback.wrap_2(:moved), 2)
true