65     void Clear(void) { mHandler = nullptr; }  in Clear()
75         mHandler = aHandler;  in Set()
85     bool IsSet(void) const { return (mHandler != nullptr); }  in IsSet()
92     HandlerType GetHandler(void) const { return mHandler; }  in GetHandler()
112         return (mHandler == aHandler) && (mContext == aContext);  in Matches()
125         return Matches(aOtherCallback.mHandler, aOtherCallback.mContext);  in operator ==()
130         : mHandler(nullptr)  in CallbackBase()
135     HandlerType mHandler;  member in ot::CallbackBase
166     using CallbackBase<HandlerType>::mHandler;
190         return mHandler(static_cast<Args &&>(aArgs)..., mContext);  in Invoke()
205         if (mHandler != nullptr)  in InvokeIfSet()
233     using CallbackBase<HandlerType>::mHandler;
245         return mHandler(mContext, static_cast<Args &&>(aArgs)...);  in Invoke()
253         if (mHandler != nullptr)  in InvokeIfSet()