Such addition is great. But there is something even better - destructors in C++. Anyone who writes C should consider using C++ instead, where destructors provide a more convenient way for resources freeing.

▲

alextingle 2 hours ago | parent | next [-]

C++ destructors are implicit, while defer is explicit.

You can just look at the code in front of you to see what defer is doing. With destructors, you need to know what type you have (not always easy to tell), then find its destructor, and all the destructors of its parent classes, to work out what's going to happen.

Sure, if the situation arises frequently, it's nice to be able to design a type that "just works" in C++. But if you need to clean up reliably in just this one place, C++ destructors are a very clunky solution.

▲

Panzerschrek an hour ago | parent [-]

Implicitness of destructors isn't a problem, it's an advantage - it makes code shorter. Freeing resources in an explicit way creates too much boilerplate and is bug-prone.

> With destructors, you need to know what type you have (not always easy to tell), then find its destructor, and all the destructors of its parent classes, to work out what's going to happen

Isn't it a code quality issue? It should be clear from class name/description what can happen in its destructor. And if it's not clear, it's not that relevant.

	▲	L-4 40 minutes ago \| parent [-]
		> Implicitness of destructors isn't a problem It's absolutely a problem. Classically, you spend most of your time reading and debugging code, not writing it. When there's an issue pertaining to RAII, it is hidden away, potentially requiring looking at many subclasses etc.

▲

flohofwoe an hour ago | parent | prev | next [-]

Desctructors are only comparable when you build an OnScopeExit class which calls a user-provided lambda in its destructor which then does the cleanup work - so it's more like a workaround to build a defer feature using C++ features.

The classical case of 'one destructor per class' would require to design the entire code base around classes which comes with plenty of downsides.

> Anyone who writes C should consider using C++ instead

Nah thanks, been there, done that. Switching back to C from C++ about 9 years ago was one of my better decisions in life ;)

▲

amluto 2 hours ago | parent | prev | next [-]

I think destructors are different, not better. A destructor can’t automatically handle the case where something doesn’t need to be cleaned up on an early return until something else occurs. Also, destructors are a lot of boilerplate for a one-off cleanup.

	▲	Panzerschrek an hour ago \| parent [-]
		> A destructor can’t automatically handle the case where something doesn’t need to be cleaned up on an early return It can. An object with destructor doing clean-up should be created only after such clean-up is needed. In case of a file, for example, a file object should be created at file opening, so that it can close the file in its destructor.

▲

mathisfun123 2 hours ago | parent | prev | next [-]

i write C++ every day (i actually like it...) but absolutely no one is going to switch from C to C++ just for dtors.

	▲	flohofwoe 25 minutes ago \| parent \| next [-]
		> but absolutely no one is going to switch from C to C++ just for dtors The decision would be easier if the C subset in C++ would be compatible with modern C standards instead of being a non-standard dialect of C stuck in ca. 1995.
	▲	kibwen an hour ago \| parent \| prev \| next [-]
		No, RAII is one of the primary improvements of C++ over C, and one of the most ubiquitous features that is allowed in "light" subsets of C++.
	▲	Pay08 2 hours ago \| parent \| prev [-]
		Weren't dtors the reason GCC made the switch?

▲

Someone 2 hours ago | parent | prev [-]

For the cases where a destructor isn’t readily available, you can write a defer class that runs a lambda passed to its constructor in its destructor, can’t you?

Would be a bit clunky, but that can (¿somewhat?) be hidden in a macro, if desired.