Comments on: The Const Nazi

By: Noel

Noel — Wed, 21 Jul 2010 21:09:06 +0000

That’s because I’m a const nazi, not a privacy nazi!

By: Reg

Reg — Wed, 21 Jul 2010 21:07:47 +0000

You are a “const nazi” while not using classes at all? What a strange combination… I think declaring variables as private is much more important than const.

By: Bill DeVoe

Bill DeVoe — Tue, 20 Jul 2010 18:28:28 +0000

Loved this and I was very encouraged that you’re using const. It’s an easy concept, but readily overlooked in computer science classes. Most students never get exposed to it in school and only some shops actively encourage its use. It is, however, so important that it’s item 3 in “Effective C++”.
Thanks for making the case and encouraging folks to use const where possible. Great advice!

By: Noel

Noel — Tue, 20 Jul 2010 14:48:50 +0000

Right now the only reason for me not to add const in the value function parameters is because I can’t copy/paste between cpp and header file (or I can, but I bring all the ugly consts along with it). It might sound silly, but minimizing extra busy work is a big deal for me. I hate having to duplicate function signatures in the header and cpp files, so I’m not about to start modifying them.

At some points in the past we had scripts to parse files and generate information or documentation or whatever. If the function declaraction and definition didn’t match exactly, it would get all confused.

By: mg

mg — Tue, 20 Jul 2010 14:39:19 +0000

MyObj const * const obj = Manager.GetObject( uuid );

const MyObj * const obj = Manager.GetObject( uuid );

const MyObj * obj = Manager.GetObject( uuid );

By: Seanba

Seanba — Mon, 19 Jul 2010 03:20:25 +0000

Hi Noel, love the video – but then again I’m another Const Nazi.

“You could actually put the const only in the function definition and it will work…”

This is my preferred method.

“… but at that point the declaration and the definition are different”

There’s probably some finer points on that but I catch your drift.

“… so you can’t copy and paste them or use other automated tools or scripts.”

Just out of curiosity what kind of automated tools or scripts are you talking about here. I get you can’t copy and paste the function signature between the defintion and declaration (which is over little concern to me) but what other tools/methodologies are undone by having const value types in the function defintion?

Great post, btw. Had a good laugh.

By: Knowing .NET » Blog Archive » Twitter Weekly Updates for 2010-07-18

Knowing .NET » Blog Archive » Twitter Weekly Updates for 2010-07-18 — Mon, 19 Jul 2010 02:00:21 +0000

[...] hates undisciplined C developers http://gamesfromwithin.com/the-const-nazi [...]

By: Frederic

Frederic — Sat, 17 Jul 2010 04:58:57 +0000

I did a search for “const” in my current C# prototype out of curiosity: I really don’t use it much at all, except for things that are seriously written in stone (such as a cube having “const int vertexCount = 8;” vertices).

The readonly keyword is useful when creating immutable structs.

By: Noel

Noel — Fri, 16 Jul 2010 23:15:23 +0000

@Jim, I think it’s only a pain to make something const-correct if you’re retrofitting it as an afterthought. If you find yourself changing something from const to non-const and having to propagate that, it probably means it’s a very serious data flow change (and the compiler “helps” you along to find where your assumptions are now wrong).

@Ivan Asset, Yes, I completely agree that it’s a pain having to have duplicate const/non-const functions sometimes. I wish there was an easy way around that (first one to mention templates or macros gets banned from posting anymore ;-b

By: ivanassen

ivanassen — Fri, 16 Jul 2010 23:03:51 +0000

What Jim Tilander said.

What leaves a bad taste in my mouth is when I have to duplicate methods (or const_cast, which is equally disgusting) to satisfy the inner Hitler. E.g. two world query functions, one of them returning const pointers to objects in range, the other returning mutable pointers.

By: obfuscatd

obfuscatd — Fri, 16 Jul 2010 20:07:13 +0000

You’re missing the const Type &var = TemporaryGenerator(…) case

http://herbsutter.spaces.live.com/blog/cns!2D4327CC297151BB!378.entry

By: Loup Vaillant

Loup Vaillant — Fri, 16 Jul 2010 15:22:41 +0000

If I may, you could also try to cut the root of the problem: the assignment statement itself: http://www.loup-vaillant.fr/tutorials/avoid-assignment

Doesn’t work very well in C++, but as soon as you have a Garbage Collector, nearly everything can be `const`.

By: Dominik Grabiec

Dominik Grabiec — Fri, 16 Jul 2010 05:09:05 +0000

Well if you changed all variables to be const by default you’d be making C/C++ into a more functional type language. Since in general variables in a functional language – if they exist at all – are a write-once read-many thing. You essentially bind a value to a name, which is what you’re doing with making the local variables const. Coincidentally also what you’re doing when making functions const, and function parameters const.

By: Christer Ericson

Christer Ericson — Fri, 16 Jul 2010 03:37:27 +0000

consts are from hell!

By: Jim Tilander

Jim Tilander — Fri, 16 Jul 2010 03:19:50 +0000

I think both me and Charles can attest to many days spent going down the rabbit hole, chasing the const correctness pipe dream. “Hm, this one thing could be const. Ops, couple of compile errors. Let me fix those. Hm, some more compile errors. Sigh, let me fix those. Ahhhrrg! I did nothing today but fix const in the codebase. What was I doing again?”

But I gotta agree, it gives me some kind of OCD satisfaction to fix them. Wonder if there is a trophy somewhere?