Comments on: Managing Object Lifetimes in D

By: The Functional Subset of D

The Functional Subset of D — Tue, 20 May 2008 14:07:25 +0000

[...] program it can not be deleted either. Like all functional languages, D features garbage collection (alongside with explicit memory management) [...]

By: The Open-Closure-Close Idiom in D

The Open-Closure-Close Idiom in D — Wed, 13 Feb 2008 13:22:33 +0000

[...] http://www.hans-eric.com Hans-Eric Grönlund on software development « Managing Object Lifetimes in D [...]

By: Hans-Eric

Hans-Eric — Sat, 09 Feb 2008 17:04:40 +0000

Ah, that is important information. Thank you for bringing attention to it.

By: Bradley Smith

Bradley Smith — Sat, 09 Feb 2008 01:40:37 +0000

Not only is the D garbage collector non-deterministic, but you can’t reference members in the destructor. Therefore, your first example may give a runtime error because f may have be collected before the LogFile’s destructor is called.

~this() { f.close; // f should not be used }

When the garbage collector calls a destructor for an object of a class that has members that are references to garbage collected objects, those references are no longer valid. This means that destructors cannot reference sub objects. This is because that the garbage collector does not collect objects in any guaranteed order, so there is no guarantee that any pointers or references to any other garbage collected objects exist when the garbage collector runs the destructor for an object. This rule does not apply to auto objects or objects deleted with the DeleteExpression, as the destructor is not being run by the garbage collector, meaning all references are valid.

The garbage collector is not guaranteed to run the destructor for all unreferenced objects. Furthermore, the order in which the garbage collector calls destructors for unreference objects is not specified.

By: Javi

Javi — Fri, 08 Feb 2008 12:51:05 +0000

Ohhh! What a constructive comment! Bravo!
And how do you know that I don’t use them???
Relax a bit and enjoy life man

By: Hans-Eric

Hans-Eric — Fri, 08 Feb 2008 11:50:04 +0000

Thank you for your nice comment. I too am “trying to pick up the language”.
I’ll keep an eye on your blog as well, especially the low-level stuff, something I haven’t done too much myself.

By: Panio Donev

Panio Donev — Fri, 08 Feb 2008 11:35:36 +0000

Man you are dumb. If you don’t trust the garbage collector, then use C or C++ like everybody else.

By: Hans-Eric

Hans-Eric — Fri, 08 Feb 2008 11:34:45 +0000

Well, I’ve come to realize that I don’t really need a deterministic destruction of objects very often. But when I do need it, the D solution to support both implicit and explicit destruction is really convenient.

Good thing you pointed out scope classes. They are great if you need to make sure the object never escapes the scope it was created in.

By: Hans-Eric

Hans-Eric — Fri, 08 Feb 2008 11:29:20 +0000

Can’t argue with this one

By: komma8.komma1

komma8.komma1 — Fri, 08 Feb 2008 01:29:41 +0000

Thanks for your help - that clarifies things a bit. It’s going to take me a while to get good at memory management again (still not nearly as bad as C++). I was a C guy back in school, but I’ve been doing C#, Java, Perl, and TCL at work for the past 8 years! It’s nice to get back to lower level programming - I’m having a lot of fun with D.