Add ParamModeBase and ParamMode, change all parameter modes to inherit from ParamMode

- Type of the extension used to store data is a template parameter
- The extension is automatically unset when the mode is unset
- Handlers inheriting from ParamMode have to provide OnSet() and SerializeParam(); may optionally provide OnUnset()
- Transparently handle the case when OnSet() modifies the mode parameter
- Remove Channel::custom_mode_params map; ask the mode handlers to serialize their parameters instead

1 files changed, 1 insertions, 0 deletions

diff --git a/include/extensible.h b/include/extensible.h
index a0544bba1..0e1afdbdf 100644
--- a/include/extensible.h
+++ b/include/extensible.h
@@ -184,6 +184,7 @@ class CoreExport LocalIntExt : public LocalExtItem
 	std::string serialize(SerializeFormat format, const Extensible* container, void* item) const;
 	intptr_t get(const Extensible* container) const;
 	intptr_t set(Extensible* container, intptr_t value);
+	void unset(Extensible* container) { set(container, 0); }
 	void free(void* item);
 };