[ori_b]

You want some sort of design document. Comments are not sufficient to describe the way that the concepts interconnect. They are almost always detail oriented, scattered and do not give the big picture.

Comments embedded in source code are singularly unsuited to giving the sort of interconnection of concepts that allows you to quickly and efficiently understand build a model of the system. They are a poor substitute for real documentation.

Something like this should always be present to describe the overarching structure of the system: ftp://gcc.gnu.org/pub/gcc/summit/2003/GENERIC%20and%20GIMPLE.pdf http://gcc.gnu.org/onlinedocs/gccint/RTL.html

Incidentally, I'm not sure if you're familiar with literate programming. That's where the code is almost an afterthought to the comments. This is an example of a literate program: http://tug.org/texlive/devsrc/Build/source/texk/web2c/tex.we.... You may be familiar with it -- it's tex, the core engine used by LaTeX. Compiled to PDF, the source looks like this: http://eigenstate.org/tmp/tex.pdf.

[flatline3]

Design documents are necessary, but are no replacement for comments. When working in GCC briefly, I found the design documents to not be nearly so valuable as the (few, poor) comments that existed in the code (objc).

[dahvyd]

The problem with comments is that they decay into irrelevance and worse, lies (that chapter of Clean Code will live with me forever). You can't write a unit test to ensure comment correctness, but you can for code correctness. Hence the code is the only reliable source of the truth.

[flatline3]

Comments only decay into irrelevance if lazy developers don't do their job. Circularly, it's developers that don't write comments that claim comments decay into irrelevance.

Imagine that.

[einhverfr]

However, for maintenance programmers to do their job, if the comments mostly describe the code, they have to ignore the comments. Why make the maintenance programmer's job any worse?

Good comments are golden, but bad comments (those that tell you what the code is doing or duplicate coding logic in the comments) are worse than useless because they make it harder to spot and read the good comments.

I think the only thing worse than an uncommented codebase is a codebase full of comments that tell you what the code is trying to do in full detail, every few lines.....

[dahvyd]

I work at a shop where we use comments sparingly if at all. Our primary product has 14m LOC and 400k unit tests. We enjoy over 75% global market share in our extremely lucrative industry. We didn't get where we are today by being "lazy" as you put it. Comments are by very definition a redundancy when the code is perfectly descriptive and self-documenting. Thus developers can get on with their job and be more productive when they don't have to duplicate their efforts for dubious benefit.

[flatline3]

> We didn't get where we are today by being "lazy" as you put it.

The two are hardly correlated.

Have you ever worked with some of the Mac OS X code written by poorer teams? For instance, the security framework? The internals of that code is a disaster at best, and yet, the core OS enjoys tremendous success and market share.

> Thus developers can get on with their job and be more productive when they don't have to duplicate their efforts for dubious benefit.

How do you determine the invariants of your APIs when writing code against a module? I don't trust arguments that boil down to "we're much too important to waste our time documenting, code is perfectly expressive!"

It's not. You're just wasting your time somewhere else, in little tiny increments, every time you have to trace code a few steps down just to figure out what it probably is supposed to do.

Or, sometimes in BIG increments, when somebody new has to learn the code base.

[dahvyd]

> the core OS enjoys tremendous success and market share.

How is that relevant? OSX has at best around 10% global market share? I'm talking market dominance here.

> How do you determine the invariants of your APIs when writing code against a module?

We flick through the well-documented code just as you would largely ignore the code and flick through well-documented comments. Here is a simple example for you:

    public class EntitySynchroniser : IEntitySynchroniser
    {
    	public EntitySynchroniser(BusinessObjectFactory factory, IDirectorySearcher directorySearcher)
    	{
    		Argument.NotNull(factory, "factory");
    		Argument.NotNull(directorySearcher, "directorySearcher");
    		this.factory = factory;
    		this.directorySearcher = directorySearcher;
    	}
    	...

The arguments here are invariant - they must not be null. I don't need a comment that may or may not be written in precisely the same format between 100 developers maintaining the codebase. I simply look for the one call to Argument.NotNull that all developers use in this case. The code is MUCH more readable than if the constructor had a comment explaining that each should not be null, mixed in with explaining what each should do. I can also determine by file searching or through the IDE which methods have these requirements.

If readers want to know what this API is and what it can do they need only look to the interface, or the implementation of it's methods in the class. Each method explains what it does by maintaining the same level of abstraction within the method. Like:

    public void MethodA()
    {
        DoFirstHighLevelThing();
        DoSecondHighLevelThing();
    }

    void DoFirstHighLevelThing()
    {
        // do less high-level things
    }

Each method call would maintain a constant level of abstraction so that the code is easily reused, easily tested and easily maintained.

> You're just wasting your time somewhere else, in little tiny increments, every time you have to trace code a few steps down just to figure out what it probably is supposed to do.

If I needed to figure out why code wasn't working the way it should what's to say a comment would be more forthcoming in explaining the reasons for the defect? Surely if MethodA did "thing A" but was really doing "thing B" the comment would tell me "thing A", therefore I'd be forced to examine the code further anyway, only I'd be hampered by the deceitful comment also? This is the nature of a defect - something that operates outside the documented behaviour of the system or module.

Not to mention that your stated opinion is that comments should explain the inner workings of things so that consumers can be well informed. This has the potential for exponential maintenance as really low level changes are made. Imagine that you change the conditions under which data access-level exceptions are raised. If anything that ever touched your data source explained what happened in exceptional circumstances you'd have to change hundreds or thousands of comments, or face the sort of comment rot I mentioned earlier. This is the real time waster!

> ...when somebody new has to learn the code base.

This is always going to be the case. Comments don't make this task any easier than a well structured codebase. A well structured codebase comes from developers making the conscious decision that any reliance on the crutch of a comment is a failure to write proper self-documenting code. A well-structured self-documenting codebase by definition requires no comments (except for the "why" not the "how", which I fully support doing by the way).