simplify to singular StaticEventHandler

Author: rmorshea

docs/source/core-concepts.rst

@@ -75,20 +75,23 @@ which we can re-render and see what changed:
 .. testcode::
 
     from idom.core.layout import LayoutEvent
+    from idom.testing import StaticEventHandler
 
+    static_handler = StaticEventHandler()
 
     @idom.component
     def ClickCount():
         count, set_count = idom.hooks.use_state(0)
-        return idom.html.button(
-            {"onClick": lambda event: set_count(count + 1)},
-            [f"Click count: {count}"],
-        )
+
+        # we do this in order to capture the event handler's target ID
+        handler = static_handler.use(lambda event: set_count(count + 1))
+
+        return idom.html.button({"onClick": handler}, [f"Click count: {count}"])
 
     async with idom.Layout(ClickCount()) as layout:
         patch_1 = await layout.render()
 
-        fake_event = LayoutEvent(target="/onClick", data=[{}])
+        fake_event = LayoutEvent(target=static_handler.target, data=[{}])
         await layout.dispatch(fake_event)
         patch_2 = await layout.render()
 
@@ -135,7 +138,7 @@ callback that's called by the dispatcher to events it should execute.
 
 
     async def recv():
-        event = LayoutEvent(target="/onClick", data=[{}])
+        event = LayoutEvent(target=static_handler.target, data=[{}])
 
         # We need this so we don't flood the render loop with events.
         # In practice this is never an issue since events won't arrive

src/idom/testing.py

@@ -13,14 +13,12 @@
     Type,
     TypeVar,
     Union,
-    overload,
 )
 from urllib.parse import urlencode, urlunparse
 from weakref import ref
 
 from selenium.webdriver import Chrome
 from selenium.webdriver.remote.webdriver import WebDriver
-from typing_extensions import Literal
 
 from idom.core.events import EventHandler
 from idom.core.hooks import LifeCycleHook, current_hook
@@ -229,52 +227,32 @@ def wrapper(*args: Any, **kwargs: Any) -> Any:
         return wrapper
 
 
-class StaticEventHandlers:
-    """Utility for capturing the target of a static set of event handlers
+class StaticEventHandler:
+    """Utility for capturing the target of one event handler
 
     Example:
         .. code-block::
 
-            static_handlers = StaticEventHandlers("first", "second")
+            static_handler = StaticEventHandler()
 
             @idom.component
-            def MyComponent(key):
+            def MyComponent():
                 state, set_state = idom.hooks.use_state(0)
-                handler = static_handlers.use(key, lambda event: set_state(state + 1))
+                handler = static_handler.use(lambda event: set_state(state + 1))
                 return idom.html.button({"onClick": handler}, "Click me!")
 
-            # gives the target ID for onClick where MyComponent(key="first")
-            first_target = static_handlers.targets["first"]
+            # gives the target ID for onClick where from the last render of MyComponent
+            static_handlers.target
     """
 
-    def __init__(self, *index: Any) -> None:
-        if not index:
-            raise ValueError("Static set of index keys are required")
-        self._handlers: Dict[Any, EventHandler] = {i: EventHandler() for i in index}
-        self.targets: Dict[Any, str] = {i: hex_id(h) for i, h in self._handlers.items()}
+    def __init__(self) -> None:
+        self._handler = EventHandler()
 
-    @overload
-    def use(
-        self,
-        index: Any,
-        function: Literal[None] = ...,
-    ) -> Callable[[Callable[..., Any]], EventHandler]:
-        ...
-
-    @overload
-    def use(self, index: Any, function: Callable[..., Any]) -> EventHandler:
-        ...
-
-    def use(self, index: Any, function: Optional[Callable[..., Any]] = None) -> Any:
-        """Decorator for capturing an event handler function"""
-
-        def setup(function: Callable[..., Any]) -> EventHandler:
-            handler = self._handlers[index]
-            handler.clear()
-            handler.add(function)
-            return handler
-
-        if function is not None:
-            return setup(function)
-        else:
-            return setup
+    @property
+    def target(self) -> str:
+        return hex_id(self._handler)
+
+    def use(self, function: Callable[..., Any]) -> EventHandler:
+        self._handler.clear()
+        self._handler.add(function)
+        return self._handler

tests/test_core/test_dispatcher.py

@@ -10,7 +10,7 @@
     SingleViewDispatcher,
 )
 from idom.core.layout import Layout, LayoutEvent
-from idom.testing import StaticEventHandlers
+from idom.testing import StaticEventHandler
 from tests.general_utils import assert_same_items
 
 
@@ -20,9 +20,9 @@ async def test_shared_state_dispatcher():
     changes_2 = []
 
     event_name = "onEvent"
-    event_handlers = StaticEventHandlers(event_name)
+    event_handler = StaticEventHandler()
 
-    events_to_inject = [LayoutEvent(event_handlers.targets[event_name], [])] * 4
+    events_to_inject = [LayoutEvent(event_handler.target, [])] * 4
 
     async def send_1(patch):
         changes_1.append(patch.changes)
@@ -48,7 +48,7 @@ async def recv_2():
     @idom.component
     def Clickable():
         count, set_count = idom.hooks.use_state(0)
-        handler = event_handlers.use(event_name, lambda: set_count(count + 1))
+        handler = event_handler.use(lambda: set_count(count + 1))
         return idom.html.div({event_name: handler, "count": count})
 
     async with SharedViewDispatcher(Layout(Clickable())) as dispatcher:
@@ -62,7 +62,7 @@ def Clickable():
                 "path": "/eventHandlers",
                 "value": {
                     event_name: {
-                        "target": event_handlers.targets[event_name],
+                        "target": event_handler.target,
                         "preventDefault": False,
                         "stopPropagation": False,
                     }

tests/test_core/test_layout.py

@@ -7,7 +7,7 @@
 import idom
 from idom.core.layout import LayoutEvent, LayoutUpdate
 from idom.core.utils import hex_id
-from idom.testing import HookCatcher, StaticEventHandlers
+from idom.testing import HookCatcher, StaticEventHandler
 from tests.general_utils import assert_same_items
 
 
@@ -287,18 +287,19 @@ def use_toggle(init=False):
 
 async def test_model_key_preserves_callback_identity_for_common_elements():
     called_good_trigger = idom.Ref(False)
-    event_handlers = StaticEventHandlers("good", "bad")
+    good_handler = StaticEventHandler()
+    bad_handler = StaticEventHandler()
 
     @idom.component
     def MyComponent():
         reverse_children, set_reverse_children = use_toggle()
 
-        @event_handlers.use("good")
+        @good_handler.use
         def good_trigger():
             called_good_trigger.current = True
             set_reverse_children()
 
-        @event_handlers.use("bad")
+        @bad_handler.use
         def bad_trigger():
             raise ValueError("Called bad trigger")
 
@@ -317,7 +318,7 @@ def bad_trigger():
     async with idom.Layout(MyComponent()) as layout:
         await layout.render()
         for i in range(3):
-            event = LayoutEvent(event_handlers.targets["good"], [])
+            event = LayoutEvent(good_handler.target, [])
             await layout.dispatch(event)
 
             assert called_good_trigger.current
@@ -329,7 +330,8 @@ def bad_trigger():
 
 async def test_model_key_preserves_callback_identity_for_components():
     called_good_trigger = idom.Ref(False)
-    event_handlers = StaticEventHandlers("good", "bad")
+    good_handler = StaticEventHandler()
+    bad_handler = StaticEventHandler()
 
     @idom.component
     def RootComponent():
@@ -346,14 +348,14 @@ def RootComponent():
     def Trigger(set_reverse_children, key):
         if key == "good":
 
-            @event_handlers.use("good")
+            @good_handler.use
             def callback():
                 called_good_trigger.current = True
                 set_reverse_children()
 
         else:
 
-            @event_handlers.use("bad")
+            @bad_handler.use
             def callback():
                 raise ValueError("Called bad trigger")
 
@@ -362,7 +364,7 @@ def callback():
     async with idom.Layout(RootComponent()) as layout:
         await layout.render()
         for _ in range(3):
-            event = LayoutEvent(event_handlers.targets["good"], [])
+            event = LayoutEvent(good_handler.target, [])
             await layout.dispatch(event)
 
             assert called_good_trigger.current