> Most of the languages that have finally clauses also have destructors.

Hm, is that true? I know of finally from Java, JavaScript, C# and Python, and none of them have proper destructors. I mean some of them have object finalizers which can be used to clean up resources whenever the garbage collector comes around to collect the object, but those are not remotely similar to destructors which typically run deterministically at the end of a scope. Python's 'with' syntax comes to mind, but that's very different from C++ and Rust style destructors since you have to explicitly ask the language to clean up resources with special syntax.

Which languages am I missing which have both try..finally and destructors?

▲ brewmarche an hour ago | parent | next [-]

In C# the closest analogue to a C++ destructor would probably be a `using` block. You’d have to remember to write `using` in front of it, but there are static analysers for this. It gets translated to a `try`–`finally` block under the hood, which calls `Dispose` in `finally`.

    using (var foo = new Foo())
    {
    }
    // foo.Dispose() gets called here, even if there is an exception

Or, to avoid nesting:

    using var foo = new Foo(); // same but scoped to closest current scope

These also is `await using` in case the cleanup is async (`await foo.DisposeAsync()`)

I think Java has something similar called try with resources.

▲ jchw 2 hours ago | parent | prev | next [-]

I don't view finalizers and destructors as different concepts. The notion only matters if you actually need cleanup behavior to be deterministic rather than just eventual, or you are dealing with something like thread locals. (Historically, C# even simply called them destructors.)

	▲	mort96 an hour ago \| parent \| next [-]
		There's a huge difference in programming model. You can rely on C++ or Rust destructors to free GPU memory, close sockets, free memory owned through an opaque pointer obtained through FFI, implement reference counting, etc. I've had the displeasure of fixing a Go code base where finalizers were actively used to free opaque C memory and GPU memory. The Go garbage collector obviously didn't consider it high priority to free these 8-byte objects which just wrap a pointer, because it didn't know that the objects were keeping tens of megabytes of C or GPU memory alive. I had to touch so much code to explicitly call Destroy methods in defer blocks to avoid running out of memory.
	▲	adrianN an hour ago \| parent \| prev \| next [-]
		Sometimes „eventually“ is „At the end of the process“. For many resources this is not acceptable.
	▲	rramadass an hour ago \| parent \| prev [-]
		> I don't view finalizers and destructors as different concepts. They are fundamentally different concepts. See Destructors, Finalizers, and Synchronization by Hans Boehm - https://dl.acm.org/doi/10.1145/604131.604153

▲ dist-epoch 2 hours ago | parent | prev [-]

Technically CPython has deterministic destructors, __del__ always gets called immediately when ref count goes to zero, but it's just an implementation detail, not a language spec thing.