Allow adding dynamic parameters to every Context

CHANGES.rst

@@ -31,6 +31,7 @@ Unreleased
 -   When generating a command's name from a decorated function's name, the
     suffixes ``_command``, ``_cmd``, ``_group``, and ``_grp`` are removed.
     :issue:`2322`
+-   Add ``dynamic_params`` property to ``Context``. :pr:`2784`
 
 
 Version 8.1.8
@@ -619,7 +620,7 @@ Released 2018-09-25
 -   Wrap ``click.Choice``'s missing message. :issue:`202`, :pr:`1000`
 -   Add native ZSH autocompletion support. :issue:`323`, :pr:`865`
 -   Document that ANSI color info isn't parsed from bytearrays in Python
-    2. :issue:`334`
+    1. :issue:`334`
 -   Document byte-stripping behavior of ``CliRunner``. :issue:`334`,
     :pr:`1010`
 -   Usage errors now hint at the ``--help`` option. :issue:`393`,

src/click/core.py

@@ -226,6 +226,11 @@ class Context:
         value is not set, it defaults to the value from the parent
         context. ``Command.show_default`` overrides this default for the
         specific command.
+    :param dynamic_params: A list of :class:`Parameter` objects that the
+        attached command will use.
+
+    .. versionchanged:: 8.2
+       Added the ``dynamic_params`` parameter.
 
     .. versionchanged:: 8.2
         The ``protected_args`` attribute is deprecated and will be removed in
@@ -278,6 +283,7 @@ def __init__(
         token_normalize_func: t.Callable[[str], str] | None = None,
         color: bool | None = None,
         show_default: bool | None = None,
+        dynamic_params: list[Parameter] | None = None,
     ) -> None:
         #: the parent context or `None` if none exists.
         self.parent = parent
@@ -425,6 +431,12 @@ def __init__(
         #: Show option default values when formatting help text.
         self.show_default: bool | None = show_default
 
+        if dynamic_params is None:
+            dynamic_params = []
+
+        #: Allow for dynamic parameters.
+        self.dynamic_params: list[Parameter] = dynamic_params
+
         self._close_callbacks: list[t.Callable[[], t.Any]] = []
         self._depth = 0
         self._parameter_source: dict[str, ParameterSource] = {}
@@ -951,11 +963,11 @@ def get_usage(self, ctx: Context) -> str:
         return formatter.getvalue().rstrip("\n")
 
     def get_params(self, ctx: Context) -> list[Parameter]:
-        rv = self.params
-        help_option = self.get_help_option(ctx)
+        rv = [*self.params, *ctx.dynamic_params]
 
+        help_option = self.get_help_option(ctx)
         if help_option is not None:
-            rv = [*rv, help_option]
+            rv.append(help_option)
 
         return rv
 

tests/test_commands.py

@@ -409,3 +409,17 @@ def cli():
     assert rv.exit_code == 1
     assert isinstance(rv.exception.__cause__, exc)
     assert rv.exception.__cause__.args == ("catch me!",)
+
+
+def test_dynamic_params(runner):
+    def callback(ctx, p, v):
+        ctx.dynamic_params.append(click.Option([f"--{v}"]))
+        return v
+
+    @click.command()
+    @click.option("--dyn", required=True, is_eager=True, callback=callback)
+    def command(dyn, **kwargs):
+        assert dyn in kwargs
+        assert kwargs[dyn] == "bar"
+
+    runner.invoke(command, ["--dyn", "foo", "--foo", "bar"])