Qt and boost comparison instructions for signals and slots




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No matter how Qt is implemented or how Boost is implemented, no additional classes are required except for the classes that define the signals and slots that must be defined.

Both implementations solve the problem of class explosion. Let's take a look at our previous analysis.

• Two different terms and their respective movements: signals and slots ;

• In a place (signal) can connect 0 or more callback functions (slots) is also many-to-many, one-to-many, many- to-many ;

• The focus is on the connection itself , not the provider or the consumer;

• no need to manually create a new class for a connection ;

• The connection is still type-safe .

These five points are at the heart of the signal slot system, and both Qt and boost have these features.

The following are the differences between the two:

	Boost.signals	Qt Signals and Slots
Signal	A signal is an object. Global, local, or member object	Signal can only be a member function
Call	Emits a signal similar to a function call Any code that has access to the signal object can send a signal.	Emits a signal similar to a function call QT provides a emit keyword to complete this operation Only the owner of the signal can send a signal.
Slot	A slot is any function or function object that can be called	Slots are specially designed member functions
return value	Can I have a return value? , the return value can be used in multiple slots	No return value
Synchronous asynchronous	Synchronous	Synchronous or (direct-attached) person Async (queue)
Thread Safety	Non-thread safe?	Thread-safe, can be used across threads
Signal Disconnect	When and only if the slots are traceable? , the connection is automatically disconnected when the slot is destroyed	When the slot is destroyed, the connection will automatically disconnect (because all slots are traceable)
Type safety	Type safety (compiler Check)	Type safety (run-time check)
Parameter list	Parameter list must be exactly the same	slots can ignore excess parameters in the signal (signal parameters can be more than slots)
	Signal, slot can be a template	Signal, slot cannot be a template
The underlying implementation	Direct implementation of C + +	Implemented by the MOC-generated meta-object (MOC and meta-object systems are directly implemented in C + +)
Introspection	No introspection mechanism	Can be found through introspection Can be called from a meta object The connection can be automatically inferred from the resource file

? is a place of doubt. It's not understood at the moment

Most importantly, the signal slot mechanism of Qt has been deeply embedded into the framework and is an integral part of it. They can be easily created, deleted, and modified using Qt-specific development tools, such as Qtcreator, in a drag-and-drop fashion. They can even be automatically generated dynamically by dynamically loading resource files and by specific named objects. These are not available in boost as a universal repository.

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Qt and boost comparison instructions for signals and slots