Functions are good. Short methods are good. Reusability is good. Properly naming your functions is good. Separation of concerns is good.

Complaining about a couple of extra carriage returns and a few extra characters to properly name the method is insanity.

Hammering these dogmas harder doesn't make them any truer, it just creates a feeling that you know what you're doing in a "If the English language was good enough for Jesus Christ then it's good enough for the state of Texas" kind of way. We have almost no empirically verified knowledge about software development. One of the few things we do know (sort of—the studies are old and shaky) is that code size is a predictor of error rates. Think that's relevant?

As Clojure, F#, Haskell and friends show, it's better to have 100 functions working on one datastructure, then having ten functions for ten datastructures.

Relevant link: http://www.slideshare.net/gvwilson/bits-of-evidence-2338367

[1] http://www.cs.yale.edu/quotes.html

What makes those languages more friendly towards smaller functions has to do with how easy it is to create a new function in those languages. Creating a function in C/C++ for instance, is a pain becouse of the boilerplate involved (header files...).

In the OP's example, he's imposing named functions on himself when he doesn't actually need to. For some reason he also declares functions within the same scope that he calls it, which just makes it cluttered in my oppinion. He would probably be alot more happy with promises.

As many as needed.

> If I add a dozen, is that better?

If your programs path needs to do 12 things, then yes. Each function should do one thing. If in documenting your function, you use the word and, that's a safe bet that you are actually writing two functions as one.

> Short methods are good—have any evidence for that? I don't think you do, because such evidence as there is points in the opposite direction (look it up in Code Complete)

Unless there is another reference I missed, Code Completes reference referred to no more than a screen's height, which at that time was ~ 25 lines. Assuming not every line is a line of code performing some action, I'd still consider that a small function.

> It's proper to name functions properly? I agree! What's "properly"?

That's hard to answer, which is why so much has been written on it. Couple that with community idiosyncrasies (like Obj-C naming vs Java), you have a lot of "proper" ways to define functions. Within the realm of the community standards, I subscribe to the thought that the method names should tend to be verb oriented. Talk about actions, or perform an action. After all, functions do something.

> We have almost no empirically verified knowledge about software development.

Well, there is quite a lot. Much of it's older (in the history of software).

> One of the few things we do know (sort of—the studies are old and shaky) is that code size is a predictor of error rates. Think that's relevant?

Be careful about this. It's not as open and shut as you'd like to think. Indeed, it's about as verifiable and confirmed as cyclomatic complexity is. Without going into too much detail and sticking strictly the context here: "code size" is an awful metric.

By that notion:

    int a = b + c; 

    int hours = timesPerformed + hoursPerPeformance;

All of those are valid deductions. After all, while it might seem obvious to remove comments, they could cause confusion, right?

And this ignores even the basic question: is a line merely a line on the screen? Or is it a languages statement? A single operation? Would a complex for clause with multiple assignments and statements count as one line?

All this is to say that code size is not the holy grail of error rates.

My own though is that taking CC and LoC and putting them together is best. A function with low complexity and with fewer lines of code is better than a longer function. Many smaller, lower complexity functions are also better than a single highly-complex function that is longer than any single function, but smaller than all the others when combined.

1. A study by Basili and Perricone found that routine size was inversely correlated with errors; as the size of routines increased (up to 200 LOC), the number of errors per LOC decreased (1984).

2. Another study found that routine size was not correlated with errors, even though structural complexity and amount of data were correlated with errors (Shen et al. 1985)

3. A 1986 study found that small routines (32 LOC or fewer) were not correlated with lower cost or fault rate (Card, Church, and Agresti 1986; Card and Glass 1990). The evidence suggested that larger routines (65 LOC or more) were cheaper to develop per LOC.

4. An empirical study of 450 routines found that small routines (those with fewer than 143 source statements, including comments) had 23% more errors per LOC than larger routines (Selby and Basili 1991).

5. A study of upper-level computer-science students found that students' comprehension of a program that was super-modularized into routines about 10 lines long was no better than their comprehension of a program that had no routines at all (Conte, Dunsmore, and Shen 1986). When the program was broken into routines of moderate length (about 25 lines), however, students scored 65% better on a test of comprehension.

6. A recent [sic!] study found that code needed to be changed least when routines averaged 100 to 150 LOC (Lind and Vairavan 1989).

7. In a study of the code for IBM's OS/360 operating system and other systems, the most error-prone routines were those that were larger than 500 LOC. Beyond 500 lines, the error rate tended to be proportional to the size of the routine (Jones 1986a).

8. An empirical study of a 148 KLOC program found that routines with fewer than 143 source statements were 2.4 times less expensive to fix than larger routines (Selby and Basili 1991).

The 25 lines is just one of the studies, related to students of CS in particular. In general, it seems like the data indicates that somewhere between 100 and 200 is optimal for minimum errors per line, lowest cost to modify, less need to modify, and overall undesirability. So the "short, 5-10 line functions" seems to be not only entirely unsupported by empirical data, but actually harmful in general.

Study 2 also supports complexity with errors, not size (small or large).

I hadn't realized how old these studies were, however. For some reason, I thought they were from the 90's. I'd be wary about relying on, what is, frankly outdated assumptions.

You'd be wary, and so you'd replace these studies with what exactly? Which of their assumptions are outdated?

Let's not fall into the trap of thinking that programmers before us didn't understand as much. As far as I can tell, the issues were much the same. A greater problem with older studies is that their sample sizes were mostly small and their experiments never replicated.

Methodologies. Languages. Practices. Tools.

You'd have to assume that nothing has changed in the last 20-30+ years in the world of programming to combat errors and defects, which is decidedly not the case.

This isn't at all to say that programmers before us didn't understand as much. Just they had different limitations.

I'll admit, I've been doing far more reading on the subject because of this thread. I still stand by the concept that a function should do one thing, and only one thing. The size of the function isn't important, but the nature of a function doing one thing generally leads to smaller functions.

I also think duplication should be removed. This also tends to remove excessive code.

On that note, and interesting discussion can be found here:

http://c2.com/cgi/wiki?LongFunctionsDiscussion

a function should do one thing, and only one thing.

I'm sure we all agree that functions should be well-defined. However, this is curiously separate from the question of how long they should be, because there are often different possible decompositions of functions into legitimate "one things" at distinct granularities.

For example, I have a rather long function in my code that builds a graph. That's clearly "one thing": you pass it what it needs to build a graph, and it returns the graph. But I could also extract smaller functions from it that also do "one thing"—to add a vertex, say, or establish an edge. In both decompositions—buildGraph by itself vs. buildGraph, addVertex and establishEdge as an ensemble—all the functions do "one thing". It's just that in the first example there is one coarse-grained "one thing", while in the second there are three finer-grained "one thing"s.

So cohesion (a function should do one thing only) doesn't tell us much about whether to prefer longer or shorter functions. All other things being equal, the coarse decomposition is arguably better than the finer-grained one, because it's simpler in two ways: it has fewer parts (1 vs. 3 in the above example), and the total code is smaller (it saves 2 function declarations).

Actually, it's fairly well established. DRY: Don't repeat yourself. Yes, if you need to assign 50 values, and each is unique, than breaking them up might be difficult. However, these aren't the rules. These are the exceptions. Heck, even your graph example could be an exception.

However, in my experience, most code does contain hits on how things can be broken up into smaller, more manageable pieces.

> the coarse decomposition is arguably better than the finer-grained one

=) The finer-grained one is arguably better than the coarse decomposition because it removes repeated lines of code and makes it easier to test the smaller methods. That the total number of lines of code is increase is unimportant, because you rarely look at all the total code in a module. Rather, you are focused on individual components. If the individual component is smaller, it makes it easier to understand.

I appreciate your point of view. And I agree, it's not easy to make things smaller without losing something. However, that doesn't mean we shouldn't try.

I did say "specifically" :)

Unless you are going to sit here and suggest that ARC or GC don't help decrease memory errors, or that languages like Python or Java haven't helped move things along. Heck, even C has been steadily improved over the years. Compilers are getting smarter. Tools like valgrind. Agile methodologies, and formalized code testing. Static analysis and even improve code reviews. Heck, even simple things like IDEs and editors.

So much has changed, so much as evolved. Does that mean everything is wrong? No. But relying on studies that can't be replicated and don't account for common programming practices and environments today is dangerous.

Your answer is that "so much has changed", you're "not going to sit here and list everything", and my question is "really just being lazy"? That's a little hard to take seriously.

I'm going to be frank, in the 80s, programmers sucked compared to today's programmers. If you took an 80s programmer and time shifted him to today, he'd look like he had no experience and really struggle until he'd spent a lot of time learning new stuff.

You've grown up with software engineering in the last 10 years. Have you honestly not seen the sea change in that time?

Be it programming languages that have shifted dramatically from the original OO in Java/C# 1.0, javascript inspiring massive changes in those languages with anonymous types, closures, etc., with unit testing, TDD. There's so much that's changed, so, so much I can't even think of half of it.

I said it below, who today passes ByRef? Or uses a global variable? 10 years ago that was common.

Just 10 years ago! The field is moving so amazingly rapidly!

And one of the real things I've seen, something you can't describe unless you've got experience, which I've no doubt you have, is that methods now actually do what they say they do. They didn't used to. They used to do other things, and touch global vars, and get passed in variables to muck around with.

And on top of that, people now seem to actually understand OO. Not just blindly recanting what polymorphic means, they can actually split up and create objects sensibly. They really couldn't do it very well 10 years ago. No-one really understood it, it sounded like a good idea but only a tiny percentage actually understood what it really meant.

And yet you think studies done back then, using techniques that would get people fired today, are worth referencing?

LOOK at the dates in the parent post. 1986? No Java, no Javascript, no Python, no Ruby, no C#. But COBOL had just released an update!

You'd better watch out for those GOTOs!

I honestly am perplexed that you can even start to think those studies are still relevant today.

You mention a long list of rules and practices, but I'm not sure they've had as unadulterated a benefit as you think. Replacing GOTOs with objects has more often than not resulted in a more structured form of spaghetti (https://en.wikipedia.org/wiki/Yo-yo_problem, for example) that's no better. There were already people programming with closures and anonymous types, there's just more of them now. That's probably better, but not night-and-day. Lots of people still write spaghetti with closures and callbacks.

Arguing about whether the past is better or the present is better is a waste of time. We're just trading generalities at this point about a topic that permits no easy generalization. One way I've been trying to avoid this trap is with the mantra (generality :), "languages don't suck, codebases suck." It forces me to remember that it's possible to write good code in a bad language, and (often) to write bad code in a good language. Intangible abilities, domain properties, accidental design decisions and cultural factors have a huge effect that it's easy to ignore and underestimate by clinging to reassuring rules about the parts that seem more tangible. But you won't grow until you try to stare into the abyss.

(Edit: By 'you' in that last sentence I didn't mean you specifically, mattmanser.)

Please do go into detail. What is some of this "quite a lot" of knowledge that sheds light on the questions at hand? It would be great to have new references.

"code size" is an awful metric

This has come up on HN before and the evidence does not support what you're saying. The gold standard in recent work [1] found that more complicated metrics have no value beyond simple program length: "After controlling for size none of the metrics we studied were associated with fault-proneness anymore."

it's about as verifiable and confirmed as cyclomatic complexity is

Do you mean they're both awful? Actually, if what you say is literally true, it follows by Occam that cyclomatic measurements are worthless, since they are far more complicated and no more valuable than the most trivial metric there is.

The studies may be weak and often old, but at least there is a body of evidence around this, and the body of evidence points reasonably consistently to the conclusion that code size is (a) the best measurement of complexity that we have, and (b) the best predictor of error rates. (The only other one I know of that has repeatedly been verified is code inspections, and that's a process not a metric.) Contradictory evidence is welcome.

It's true that there's a debate around how best to measure code size. But that's a separate question. That also has received some pretty high-quality discussion on HN in the past--see the link below. It changed my thinking, for one; I highly recommend the comments by anon_d in that thread.

[1] http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.20.2...,

via http://blog.vivekhaldar.com/post/10669678292/size-is-the-bes...,

discussed at https://news.ycombinator.com/item?id=3037293.

In practice I find I'm a terrible judge at where the function boundaries should be. Several times I've tried to reorganize a project where functions had gotten gradually too big, ended up making them too small and numerous and having a pain debugging, then finally settling on some intermediate position. All the overly-certain talk of "as many functions as you need" misses these nuances.

(I wrote recently about global vs local readability: http://akkartik.name/blog/readable-bad)

I meant that everytime somebody refers to the value of controlling code size (like gruseom did in this thread), we have to deal with the inevitable strawman of:

    int a = b + c;

    int hours = timesPerformed + hoursPerPeformance;

(PG has also said this many many times with reference to arc.)

Code Complete still has many lessons to teach, but it's certainly not gospel in this day and age (unfortunately my copy is buried in some boxes from a move and I can't find it at the mo to re-read that chapter!).

I personally have seen massive changes to the way we code, people just seem to understand how to split out code into more logical chunks than they used to. Even as recently as 8 years ago, when I start professionally, I remember people used to constantly ask how to pass variables by reference, global variables, all sorts of nastiness that meant that methods weren't really being used properly. These days I honestly haven't seen a by ref pass or a global variable for years (apart from in an old, truly terrible VB.Net program I've just been given to maintain & update, ugh).

Programming really has changed massively. And there certainly are fairly famous proponents of short functions out there, Kent Beck, Robert Martin. It's advice that's changed over the last 20 years, but I don't know whether there's studies to back it up, all I can give you is that the general consensus seems to have changed.

Back to the point, I certainly don't hate long methods, what I hate is methods that do many different things. That's just bad code in my book, especially if they start bleeding lines into each other and get jumbled up as tends to happen as your code ages.

I admit it's very easy to go too far down the rabbit hole, with a massive tree of confusingly nested methods and it's a balancing game.

But when you see a long function you can usually tell straight away whether it's justified or not. Is it doing a complicated thing that justifies a hundred or two hundred lines or is it just doing loads of little simple things.

And often if it's doing simple things, invariably other functions in the same code file will also be doing those simple things with tiny variations and it can be refactored to reduce the TLOC and improve maintainability when you need to update that functionality. And that's usually a sign of a programmer how hasn't learnt to do DRY yet and is relatively inexperienced (in the .Net world anyway, I'm not having a dig at all, I appreciate js still massively changes every year).

A function that does one thing and one thing only is:

- generally short

- testable

- name it intelligently and then others don't even have to read the code to know what it does

- easier to spot bugs

- functionality doesn't get mixed up

- reusable code becomes a lot more obvious

Some of these hold especially true with javascript given its lack of block scope.

Long functions are generally a strong code smell, in my experience anyway. They generally contain bad code, regardless of whether they'd have been broken up or not. Functions that start declaring random anonymous objects, which I see a lot in javascript, are especially dubious. It's an artefact of javascript's design that because it's so difficult to declare reusable objects and namespaces and manage code between files a lot of javascript programmers just end up writing these huge blobs of code.

As to where I see this happening in javascript, as an example I was reading Meteor.js's code the other day and was actually surprised at just how bad the code is. Every function seems to do 5 different things, it declares object right in the middle of functions rather than extracting it out, loads of frankly crazy coding practices.

EDIT: In fact, now that I think about it, I remember once using that bit of CC to argue that long functions were better discussing it with a friend. Funny how you can do a complete 180 over time.

This is true only if the function decomposition is intelligently done. The problem is that with callbacks, the function decomposition is forced on you based on what needs to be done asynchronously (i.e., mostly I/O). As a result, it breaks apart the flow of control into little tiny pieces that may be only loosely coupled with the most logical way to decompose functionality.

So your statement may be true in general, but it may not be applicable when it comes to how to best handle callback functions.

If that function is required multiple places, you make a proper function out of it, and pass that function instead of a lambda.

Callbacks allow for abstractions like map, filter, reduce... Used properly, they can actually increase reusability instead of prohibiting it.

wtfFriendAction is additionally a very, very poor name. It should be called "addFriendToFriendList" or something. Another thing is that the author himself states that the function doesn't actually makes sence, hence the ugly name.

That's the point — using callbacks you end up with functions which do not make sense...

Edit: spelling