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bDS2/lib/bds/desktop/ui_locale.ex

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3.0 KiB
Elixir

defmodule BDS.Desktop.UILocale do
@moduledoc """
Per-render UI locale binding for the desktop LiveView shell.
The shell renders the UI in the user's selected language, which can differ
from the OS locale and from the project's `mainLanguage`. Phoenix HEEx
templates call `translated/1,2` helpers without an explicit locale, so we
bind the active locale once per `render/1` and the helpers read it back.
This module encapsulates that binding so call sites do not touch the raw
process dictionary directly. Use `with_locale/2` around any render or
component that needs a locale binding; use `current/0` to read it.
## Invariant
Every code path that evaluates HEEx templates containing `translated/1,2`
calls **must** call `UILocale.put/1` before template evaluation:
* `ShellLive.render/1` — sets locale at the top of every LiveView render.
* `SidebarComponents.sidebar_content/1` — sets locale before the function
component's HEEx (runs in the same process, may be called outside
the parent render cycle via `send_update`).
* `MenuBar.mount/1` and `MenuBar.handle_info({:set_ui_locale, _})` — set
locale in the separate menu-bar process which has its own render cycle.
Violating this invariant causes `current/0` to return a stale or `nil`
locale, producing untranslated UI text.
Direct use of `Process.put(:bds_ui_locale, _)` or
`Process.get(:bds_ui_locale)` is forbidden outside this module.
"""
@key :bds_ui_locale
@typedoc "A normalized UI locale code such as `\"en\"` or `\"de\"`."
@type locale :: String.t() | nil
@doc """
Bind `locale` for any subsequent reads of `current/0` in this process.
Used at LiveView render boundaries. The binding persists past the call
(mirroring per-process locale state) so that lazily evaluated child
components see the active locale. Each render boundary overwrites it.
"""
@spec put(locale()) :: :ok
def put(locale) do
Process.put(@key, locale)
BDS.Gettext.put_locale(locale)
:ok
end
@doc """
Set the UI locale for the duration of `fun`, then restore the prior value.
Safe under exceptions: the prior binding is restored in an `after` clause.
Use this for short-lived non-LiveView contexts (background tasks, scripts)
where eager evaluation guarantees the binding is consumed before `fun`
returns. Do not use around LiveView `render/1` because the returned
`Phoenix.LiveView.Rendered` struct evaluates its dynamic parts lazily.
"""
@spec with_locale(locale(), (-> result)) :: result when result: var
def with_locale(locale, fun) when is_function(fun, 0) do
previous = Process.get(@key)
Process.put(@key, locale)
try do
fun.()
after
restore(previous)
end
end
@doc """
Read the active UI locale binding for this process, or `nil` when unset.
"""
@spec current() :: locale()
def current, do: Process.get(@key)
defp restore(nil), do: Process.delete(@key)
defp restore(value), do: Process.put(@key, value)
end