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All TermControl/TermApp/TermConnection event handlers should be TypedEventHandlers #1104
Description
WinRT design guidelines dictate that event handlers should have two arguments, T and EventArgs. For any class T that produces an event, this ensures that the event handler can identify which instance of T fired the currently-handled event.
The signature for an event handler delegate should consist of two parameters: sender (
IInspectable), and args (some event argument type, for exampleRoutedEventArgs).
Given that we are exposing an internal API, we can specify a more specific T than IInspectable.
C++/WinRT supports this by way of winrt::TypedEventHandler<T, Args...>.
We should move all the TermConnection, TermApp and TermControl event handlers to use TypedEventHandlers.
bonus
We can get rid of DECLARE_EVENT and DEFINE_EVENT, and augment DECLARE_EVENT_WITH_TYPED_HANDLER (and DEFINE...TYPED) to use typename class_type as the sender type, so that we don't need to repeat ourselves:
terminal/src/cascadia/inc/cppwinrt_utils.h
Lines 42 to 47 in 880272c
-#define DECLARE_EVENT_WITH_TYPED_EVENT_HANDLER(name, eventHandler, sender, args) \
+#define DECLARE_EVENT_WITH_TYPED_EVENT_HANDLER(name, eventHandler, args) \
public: \
- winrt::event_token name(Windows::Foundation::TypedEventHandler<sender, args> const& handler); \
+ winrt::event_token name(Windows::Foundation::TypedEventHandler<typename class_type, args> const& handler); \ void name(winrt::event_token const& token) noexcept; \
private: \
- winrt::event<Windows::Foundation::TypedEventHandler<sender, args>> eventHandler;
+ winrt::event<Windows::Foundation::TypedEventHandler<typename class_type, args>> eventHandler;which, when used, becomes:
-DECLARE_EVENT_WITH_TYPED_EVENT_HANDLER(PasteFromClipboard, _clipboardPasteHandlers, TerminalControl::TermControl, TerminalControl::PasteFromClipboardEventArgs);
+DECLARE_EVENT_WITH_TYPED_EVENT_HANDLER(PasteFromClipboard, _clipboardPasteHandlers, TerminalControl::PasteFromClipboardEventArgs);
Activity
Remove the FontSizeChanged event from TermControl (#15867)