Features are social processes

For a while now I've been thinking about how human languages evolve compared to how computer languages are designed and how that relates to the features of the respective languages. In this post I will ramble at bit about how the meaning of software related terms is defined. I'll also discuss hard and soft features in programming languages and how the community surrounding the language affects, and is affected by, those features.

This is mostly a bunch of ideas and observations that I'm trying to put into words to 1) make me understand them better, and 2) make sure I don't forget them. If you expect a scientific survey, then I'm sorry to disappoint you. Maybe, though, you'll find food for your own thought and ideas.

What's a language?

As I see it, languages (be it the human or programming kind) are mutual agreement between the communicating parts of what a statement means. If everyone have a different opinion of what the following statement means, then it effectively doesn't have any meaning at all since we can't use it to communicate with anyone:

You need wood from a forest to create a fire.

or in computer-speak:

Fire fire = new Fire(forest.getWood());

On the other hand, when we agree upon what this phrase mean, then we can do all kinds of things: discuss its correctness, use it in another context, abstract it to cover more and general cases, write a compiler for it, etc.

For example, the common breed of C compiler accepts a lot of code most C programmers won't. It's the users of the C language that defines the subset of allowed-by-the-compiler-C that is acceptable for us to use. In other words, the C standard can say all it wants; its the C users who in the end defines the (practical) C language. It a bit like if physics would say "Our universe have 11 dimensions. Go use all of them!", but all known users of the universe are three-dimensional beings, thus, the accepted subset of the universe is three-dimensional. Sorry to break it to you, physics, but that's how it is.

Language features are all about what the community around the language make of the language. In a way, language features are just as much a technical aspect of the language as a social aspect of it. Example: is a language feature that's not accepted by the community really a feature, or is it just useless language complexity? More extreme example: a language without users but with extremely powerful features; effectively, does that language have any features at all?

I would also say that anyone aiming to develop a successful programming language (without the backing of a *caugh* Sun huge *caugh* Microsoft corporation) needs to have equally good eye for the technical aspect as well as the social aspect. (S)he needs to understand the social processes involved for getting a community of users who agree (hopefully with the language designer) on how the language should be used. (I think python is good example of such community, by the way).

What about software?

Developing software is also a social process. For example, you get requirements from your customer, you discuss the requirements in order to understand them, and you implement them. Implementing requirement are also a social process: you design the code by discussing it with your colleagues. And what words do you use for doing that?

You use words like object, generic, sort, inheritance, stack, tree, operation, method, message, reuse, client, algorithm, allocation, port, framework, mapping, service, channel, process, decoupled, assumption, resource, provider, input, interface... I could go on forever, but the point is that none of these words really mean anything if we humans don't agree on what they mean. The computer, framework, or programming language has no opinion on what "decouple the client's mapping algorithm from the port allocation" means, but programmers do. It's important it means that same to all programmers involved.

Soft and hard

How does this relate to programming language features? I think there two different kinds of features: hard features that was (deliberately) designed into the language, and soft features that are concepts and idioms that have evolved from using the language.

Hard features are concrete. You can make a list of hard features by reading the language specification. Soft features, on the other hand, are not. They are embedded in the community and to enumerate them you need to vibe with it for a while. Hard features are taught in classes and in books; soft features are learned by hacking, hacking, living and breathing, and some more hacking.

Example: C++ templates. Originally intended to provide better type-safety when writing generic code, like std::vector. The C++ community has then discovered that templates can be used for much, much more (like Boost.Spirit). There are a lot of template code written to implement various kinds of abstract features, e.g., compile-time if, compile-time strings, domain specific languages, etc. The hard feature is "write type-safe generic code". The soft features are "compile-time if", "embedded DSL", and even "it's hard, but you can evaluate everything at compile-time".

The D language took these soft features of C++ templates (e.g., compile-time if, embedded DSL) and integrated them into the core language. Thus, enabled more programmers to use them, because of easier syntax, error messages, compiler support, documentation, etc.

So when a C++ programmer talks about enabling or disabling some piece of code (s)he needs to think about some abstract concept like the enable-if template, while a D programming just thinks "static if". In fact, I don't think the D programmer even thinks "static if" because it's so natural to them, just as the more common "dynamic if" is so natural to all of us. The D programmer probably thinks in entirely other abstract concepts because his/her mind is free from the horrible details of C++ templates meta-programming.

You may argue that our mind is very good at abstracting and that this isn't a problem in practice, but I don't think that's true at all. Example: very few C++ programmer have every done something like an template computing the sinus of an angle, so when they're told to optimize a piece of code doing trigonometry what they'll do is to use some kind of table look-up. A D programmer, on the other hand, will simply slap together a sinus function that can be evaluated statically by the compiler because compile-time evaluation is nothing magic to her/him. (In fact, in D 2.0 match function will automatically be evaluated at compile-time if their arguments are constants).

What I'm saying here is that compile-time evaluation is a (hard) language feature of D but not of C++ (where it is an soft feature). Sure, you can in theory do compile-time evaluation of everything you need in C++ (templates are Turing complete), but not in practice because it's so hard that you actively avoid it. Thus, in most programmers conscious mind, C++ does not have compile-time evaluation. Similarly, you can do object-oriented programming in C, but you probably don't because it's hard and littered with horrible details. Thus, C is in most programmers mind not a object-oriented language. It's possible to do structured programing in Commodore BASIC, but most of us don't think of it like that. Got my point yet? Good.

Ok, so what?

By now you are probably thinking "that's all very interesting, but how is this useful?". Well, I did say that this post was a rambling, didn't I? :)

Seriously though, I don't really think any of this will make you a better software developer, but I think it could be useful if you are developing an tool and there's a community of users around it. Be sure to note what kinds of words the users uses, what features they ignore, what idioms they invent, etc. Integrate the words and idioms into the tool and it's documentation to make the experience for a new user of the application more consistent.

The firge, the door and the fire alarm

Today when I prepared breakfast I realized that the fridge wasn't properly closed. It had been a small opening the whole night. That's not particularly good.

But what's worse is that the fridge did not make any noise indicating that the door was open. In fact, it did the opposite: it turned off the only indication there was that the door wasn't properly closed -- it turned of the light inside the fridge. If that light wasn't turned off it would be easier to spot that the door was open.

Turning the light off would not be a big problem if there was some way the fridge alarmed when the door was open. Let's say making a noise when it had been open for more than 1 minute.

I'm sure that it's a feature that the fridge turns off the light by it self when it has been on for too long. But I can't the use-case when it would be a useful. There must be a timer somewhere that turns off the light. That timer should instead trigger an alarm.

Actually there is an noise-making-device in the fridge. But that only used when the temperature in the fridge is above a certain temperature. That noise-making-devices should be triggered by that timer. Why didn't it?

I don't know.

Recently I've noticed more and more weird design choices in everyday things. Like having the handle of a door be shaped as a pipe when you should push the door, and having the handle be shaped like a flat surface when you should pull the door (think about it, a surface is easy to push and a pipe is easy to pull).

Even worse, I've experienced that fire alarms sounds very very much like the break-in alarm.

It's 2009 and you can't read a forwarded mail

The other day, a college sent me a mail that I simply forwarded from Outlook to my Gmail. Today, when I finally had time to read it I opened it in Gmail. What do you think the mail contains? Nothing, except an attached file called smime.p7m. This file contains the encrypted mail, apparently, so I can't read it.

Oh, please! Come on! Why is a simple thing like this so hard?! Really... seriously, I'm failing to forwardning an e-mail...? Are we really making progress?

Yeah, I know that I should have forwarded it without encryption. But why is this something I need to know about? The mail client should tell me that the receiver won't be able to read the mail... It's freaking 2009! Not 1979!

Who knows... in 3009, perhaps we humans have evolved enough to have figured out and understand this whole send plain stupid text to another person-thingie. It's apparently too advanced to grasp for the current generation of humans.

(I have high hopes for the next-gen humans, though... No, really. I do!)

Contracts? Test-driven? Insight!

The other day I pair-programmed with a new guy at work. He showed my a class and its tests he and another guy had written a few week earlier. I don't recall exactly what the class did, but it was quite simple, hence the tests was short and simple. Overall well written tests if you ask me.

As we looked at the tests we had the following conversation, which afterwards gave me an new insight to an idea I've had a long while: tests are contracts.
He: Most of these tests are for testing that the class logs correctly...
Me: Yes, is that a problem?
He: Well, I know TDD says that you need to write a failing test before you're allowed to write any production code. But isn't testing logging a bit over-kill?
Me: I understand what you mean. What kind of logging is this? Why does the class need to log?
He: We needed it to understand the code. For debugging.
Me: Is the logging needed now? Is there some script that parses these logs, for example?
He: No, it's not needed any more.
Me: In that case I'd say that these tests isn't needed.

I could go even further and say that those tests shouldn't be written at all and should be removed. I actually think that tests like these are more confusing then anything else. I'm not saying those two guys who wrote these tests did anything wrong; they were doing TDD and was doing TDD right. What I'm saying is that, in my opinion, TDD isn't ideal.

Yeah, I hear you're cries: What?! Heresy! Calm down. I'll try to explain.

My opinion is that a class' tests should define what the class has to fulfill to be considered correct. To be precise, with 'correct' I mean 'what makes all things that depend on the class behave correctly'. (I realize that this is an recursive definition of 'correct', but you're a human being so you can handle it. :))

Recall that my pair-programming partner said that the logging wasn't needed any more. This means that we could remove the part of the code that logs and the class would still be correct according to the definition above. However, the class would not pass its tests because of the tests that tests the logging. This means that the class is over-specified. This is bad. The solution? Ditch the logging tests!

And so my fellow pair-programmer did.

I often say that test-methods should be named shouldFoo since it makes you focus on the behavior that is tested instead of the part that is tested (the tested method for example). I'm thinking of extending this tip to nameing test-methods as shouldFooBecauseBar. If this convention was followed, the the test-methods that tests the logging whould be named shouldLogBecauseWeNeedItforDebugging. That name sound a bit silly, doesn't it? That because it is silly to test it!

As I said, a class' tests defines what the class has to fulfill to be correct. In other words, the tests is the contract that the class must fulfill. Having tests that define contracts is much better, I think, than having tests for every little piece of functionality a class have (i.e., TDD). One reason is that it makes it easier to understand how you can change the class without breaking anything.

Now don't get me wrong, TDD is great, really great. But is it perfect? Of course not, that would be very naive to think (not to mention boring: Nothing more to do here, we've find the ideal solution! Now, let's drink tea all day!).

Is contracts ideal? Probably not. It contracts better? Yes, I think so.

Inheritance is overrated

I like the object-oriented way of developing software -- especially if there is some functional flawor in it. In most language it is fairly easy to at least emulate a functional programming language by simply changing the way you think about the problem and the solution.

When I think in an functional way about a problem I have to solve using an object-oriented language, objects become collections of related functions (with this I mean pure function, i.e., they have no side effects). That is, I think about the program as lambdas that is passed around, rather than instances of classes. This may sound like a trivial and superficial difference but it is not.

I have found that if I solve a problem in a functional way, the components of the solution (functions, classes, etc) are less coupled than if I solve it in an object-oriented way. Why is this?

One reason it that an object A is provided with objects B..Z that A needs for doing whatever it needs to do. That is, A only relies on that it gets something that it useful for its purposes, instead on relying on a particular implementation. Another reason is that classes' methods are often pure functions, which decreases coupling because classes does not depend on the state of another class or in which order methods are called.

Enough rambling. Now to the point. The first reason basically says that a functional mind-set results in an structure of has-a relations between objects, instead of the "object-oriented way" is-a. With "is-a" I mean class-inheritance (the extends keyword in Java), which is the strongest way of coupling two classes and the most difficult to reuse, refactor, and understand -- at least for me.

On the other hand, I find interface-inheritance (the implements keyword in Java) very useful and I rely on it dayly.

If find it a bit funny that during the years I have used object-oriented languages, I have not once used inheritance... without regretting it. I'm getting better and better, of course, and during the last year I haven't used inheritance at all... and I'm not regretting it.

Maybe it just me, but I find inheritance overrated.