# Source: https://github.com/bigskysoftware/htmx/blob/master/www/content/essays/codin-dirty.md

+++
title = "Codin' Dirty"
description = """\
  In this article, Carson Gross discusses an alternative approach to software development that challenges the \
  principles outlined in 'Clean Code.' Carson advocates for allowing larger functions in certain cases, preferring \
  integration tests over unit tests, and minimizing the number of classes and interfaces. He shares examples from \
  successful software projects that demonstrate these practices can lead to maintainable, high-quality code."""
date = 2024-11-24
updated = 2024-11-24
authors = ["Carson Gross"]
[taxonomies]
tag = ["posts"]
+++

<center>

![quick-and-dirty](/img/quick-and-dirty.png)

</center>

> “Writing clean code is what you must do in order to call yourself a professional. There is no reasonable excuse for 
> doing anything less than your best.” [Clean Code](https://www.goodreads.com/book/show/3735293-clean-code)

In this essay I want to talk about how I write code.  I am going to call my approach "codin' dirty" because I often
go against the recommendations of [Clean Code](https://www.amazon.com/Clean-Code-Handbook-Software-Craftsmanship/dp/0132350882),
a popular approach to writing code.

Now, I don't really consider my code all that dirty: it's a little gronky in places but for the most part I'm 
happy with it and find it easy enough to maintain with reasonable levels of quality.

I'm also *not* trying to convince *you* to code dirty with this essay.  Rather, I want to
show that it is possible to write reasonably successful software this way and, I hope, offer some balance around software
methodology discussions.

I've been programming for a while now and I have seen a bunch of different approaches to building software work.  Some 
people love Object-Oriented Programming (I like it), other very smart people hate it.  Some folks love the expressiveness 
of dynamic languages, other people hate it. Some people ship successfully while strictly following Test Driven Development, 
others slap a few end-to-end tests on at the end of the project, and many people end up somewhere between these extremes.

I've seen projects using all of these different approaches ship and maintain successful software.

So, again, my goal here is not to convince you that my way of coding is the only way, but rather to show you (particularly
younger developers, who are prone to being intimidated by terms like "Clean Code") that you can have a successful 
programming career using a lot of different approaches, and that mine is one of them.

## TLDR

Three "dirty" coding practices I'm going to discuss in this essay are:

* (Some) big functions are good, actually
* Prefer integration tests to unit tests
* Keep your class/interface/concept count down

If you want to skip the rest of the essay, that's the takeaway.

## I Like Big Functions

I think that large functions are fine. In fact, I think that *some* big functions are usually a *good* thing in a codebase.

This is in contrast with Clean Code, which says:

> “The first rule of functions is that they should be small. The second rule of functions is that they should be 
> smaller than that.” [Clean Code](https://www.goodreads.com/book/show/3735293-clean-code)

Now, it always depends on the type of work that I'm doing, of course, but I usually tend to organize my functions into the 
following:

* A few large "crux" functions, the real meat of the module.  I set no bound on the Lines of Code (LOC) of these functions,
  although I start to feel a little bad when they get larger than maybe 200-300 LOC.
* A fair number of "support" functions, which tend to be in the 10-20 LOC range
* A fair number of "utility" functions, which tend to be in the 5-10 LOC range

As an example of a "crux" function, consider the [`issueAjaxRequest()`](https://github.com/bigskysoftware/htmx/blob/7fc1d61b4fdbca486263eda79c3f31feb10af783/src/htmx.js#L4057)
in [htmx](https://htmx.org).  This function is nearly 400 lines long!

Definitely not clean!

However, in this function there is a lot of context to keep around, and it lays out a series of specific steps that must
proceed in a fairly linear manner.  There isn't any reuse to be found by splitting it up into other functions and I
think it would hurt the clarity (and also importantly for me, the debuggability) of the function if I did so.

### Important Things Should Be Big

A big reason I like big functions is that I think that in software, all other things being equal, important things should 
be big, whereas unimportant things should be little.

Consider a visual representation of "Clean" code versus "Dirty" code:

<div style="padding: 1em">

![clean-v-dirty.png](/img/clean-v-dirty.png)

</div>

When you split your functions into many equally sized, small implementations you end up smearing the important parts of your
implementation around your module, even if they are expressed perfectly well in a larger function.

Everything ends up looking the same: a function signature definition, followed by an if statement or a for loop, maybe a function 
call or two, and a return.

If you allow your important "crux" functions to be larger it is easier to pick them out from the sea of functions, they 
are obviously important: just look at them, they are big!

There are also fewer functions in general in all categories, since much of the code has been merged into larger functions.
Fewer lines of code are dedicated to particular type signatures (which can change over time) and it easier to keep the
important and maybe even the medium-important function names and signatures in your head.  You also tend to have fewer 
LOC overall when you do this.

I prefer coming into a new "dirty" code module: I will be able to understand it more quickly and will remember the
important parts more easily.

### Empirical Evidence

What about the empirical (dread word in software!) evidence for the ideal function size?

In [Chapter 7, Section 4](https://flylib.com/books/en/2.823.1.64/1/) of [Code Complete](https://en.wikipedia.org/wiki/Code_Complete),
Steve McConnell lays out some evidence for and against longer functions.  The results are mixed, but many
of the studies he cites show better errors-per-line metrics for *larger*, rather than smaller, functions.

There are [newer studies](https://arxiv.org/pdf/2205.01842#:~:text=In%20this%20paper%20we%20examine,also%20decreases%20overall%20maintenance%20efforts) 
as well that argue for smaller functions (<24 LOC) but that focus on what they call "change-proneness".  When it comes to
bugs, they say:

> Correlations between SLOC and bug-proneness (i.e., #BuggyCommits) are significantly lower than the four 
> change-proneness indicators.

And, of course, longer functions have more code in them, so the correlation of bug-proneness _per line of code_ will be 
even lower.

### Real World Examples

How about some examples from real world, complex and successful software?

Consider the [`sqlite3CodeRhsOfIn()`](https://github.com/sqlite/sqlite/blob/70989b6f5923a732b0caee881bd7c3ff8859e9c5/src/expr.c#L3502)
function in [SQLite](https://sqlite.com/), a popular open source database.  It looks to be > 200LOC, and a walk around the SQLite
codebase will furnish many other examples of large functions.  SQLite is noted for being extremely high quality and
very well maintained.

Or consider the [`ChromeContentRendererClient::RenderFrameCreated()`](https://github.com/chromium/chromium/blob/6fdb8fdff0ba83db148ff2f87105bc95e5a4ceec/chrome/renderer/chrome_content_renderer_client.cc#L591)
function in the [Google Chrome](https://www.google.com/chrome/index.html) Web Browser.  Also looks to be over 200 LOC.  Again, poking around the codebase
will give you plenty of other long functions to look at.  Chrome is solving one of the hardest problems in software:
being a good general purpose hypermedia client.  And yet their code doesn't look very "clean" to me.

Next, consider the [`kvstoreScan()`](https://github.com/redis/redis/blob/3fcddfb61f903d7112da186cba8b1c93a99dc87f/src/kvstore.c#L359)
function in [Redis](https://redis.io/).  Smaller, on the order of 40LOC, but still far larger than Clean Code would
suggest.  A quick scan through the Redis codebase will furnish many other "dirty" examples.

These are all C-based projects, so maybe the rule of small functions only applies to object-oriented languages, like
Java?

OK, take a look at the [`update()`](https://github.com/JetBrains/intellij-community/blob/8c6cc1579ac358451ba2c5b8a54853249fdc5451/java/compiler/impl/src/com/intellij/compiler/actions/CompileAction.java#L60)
function in the `CompilerAction` class of [IntelliJ](https://www.jetbrains.com/idea/), which is roughly 90LOC.  Again, 
poking around their codebase will reveal many other large functions well over 50LOC.

SQLite, Chrome, Redis & IntelliJ...

These are important, complicated, successful & well maintained pieces of software, and yet 
we can find large functions in all of them.  

Now, I don't want to imply that any of the engineers on these projects agree with this essay in any way, but I think 
that we have some fairly good evidence that longer functions are OK in software projects.  It seems safe to say that
breaking up functions just to keep them small is not necessary.  Of course you can consider doing so for other reasons
such as code reuse, but being small just for small's sake seems unnecessary.

## I Prefer Integration Tests to Unit Tests

I am a huge fan of testing and highly recommend testing software as a key component of building maintainable systems.

htmx itself is only possible because we have a good [test suite](https://htmx.org/test) that helps us ensure
that the library stays stable as we work on it. 

If you take a look at the [test suite](https://github.com/bigskysoftware/htmx/blob/master/test/core/ajax.js) one thing
you might notice is the relative lack of [Unit Tests](https://en.wikipedia.org/wiki/Unit_testing).  We have very few
test that directly call functions on the htmx object.  Instead, the tests are mostly 
[Integration Tests](https://en.wikipedia.org/wiki/Integration_testing): they set up a particular DOM configuration
with some htmx attributes and then, for example, click a button and verify some things about the state of the DOM afterward.

This is in contrast with Clean Code's recommendation of extensive _unit testing_, coupled with Test-First Development:

> **First Law** You may not write production code until you have written a failing unit test.
> **Second Law** You may not write more of a unit test than is sufficient to fail, and not compiling is failing.
> **Third** Law You may not write more production code than is sufficient to pass the currently failing test.
> 
> --[Clean Code](https://www.goodreads.com/book/show/3735293-clean-code)

I generally avoid doing this sort of thing, especially early on in projects.  Early on you often have no
idea what the right abstractions for your domain are, and you need to try a few different approaches to figure out what
you are doing.  If you adopt the test first approach you end up with a bunch of tests that are going to break as you 
explore the problem space, trying to find the right abstractions.  

Further, unit testing encourages the exhaustive testing of every single function you write, so you often end up having more 
tests that are tied to a particular implementation of things, rather than the high level API or conceptual ideas of the
module of code.

Of course, you can and should refactor your tests as you change things, but the reality is that a large and growing test 
suite takes on its own mass and momentum in a project, especially as other engineers join, making changes more and more
difficult as they are added.  You end up creating things like test helpers, mocks, etc. for your testing code.

All that code and complexity tends over time to lock you in to a particular implementation.

### Dirty Testing

My preferred approach in many projects is to do some unit testing, but not a ton, early on in the project and wait 
until the core APIs and concepts of a module have crystallized.  

At that point I then test the API exhaustively with integrations tests.

In my experience, these integration tests are much more useful than unit tests, because they remain stable and useful 
even as you change the implementation around.  They aren't as tied to the current codebase, but rather express higher level
invariants that survive refactors much more readily.

I have also found that once you have a few higher-level integration tests, you can then do Test-Driven development, but
at the higher level: you don't think about units of code, but rather the API you want to achieve, write the tests for that
API and then implement it however you see fit.

So, I think you should hold off on committing to a large test suite until later in the project, and that test suite
should be done at a higher level than Test-First Development suggests.  

Generally, if I can write a higher-level integration test 
to demonstrate a bug or feature I will try to do so, with the hope that the higher-level test will have a longer shelf
life for the project.

## I Prefer To Minimize Classes

A final coding strategy that I use is that I generally strive to minimize the number of classes/interfaces/concepts in 
my projects.

Clean Code does not explicitly say that you should maximize the # of classes in your system, but many recommendations it
makes tend to lead to this outcome:

> * "Prefer Polymorphism to If/Else or Switch/Case"
> * "The first rule of classes is that they should be small. The second rule of classes is that they should be smaller 
>   than that."
> * "The Single Responsibility Principle (SRP) states that a class or module should have one, and only one, reason to 
>    change."
> * "The first thing you might notice is that the program got a lot longer. It went from a little over one page to 
>    nearly three pages in length."

As with functions, I don't think classes should be particularly small, or that you should prefer polymorphism to a 
simple (or even a long, janky) if/else statement, or that a given module or class should only have one reason to change.

And I think the last sentence here is a good hint why: you tend to end up with a lot more code which may be of little 
real benefit to the system.

### "God" Objects

You will often hear people criticise the idea of ["God objects"](https://en.wikipedia.org/wiki/God_object) and I
can of course understand where this criticism comes from: an incoherent class or module with a morass of unrelated 
functions is obviously a bad thing.

However, I think that fear of "God objects" can tend to lead to an opposite problem: overly-decomposed software.

To balance out this fear, let's look at one of my favorite software packages, 
[Active Record](https://guides.rubyonrails.org/active_record_basics.html).

Active Record provides a way for you to map ruby object to a database, it is what is called an 
[Object/Relational Mapping](https://en.wikipedia.org/wiki/Object%E2%80%93relational_mapping) tool.

And it does a great job of that, in my opinion: it makes the easy stuff easy, 
the medium stuff easy enough, and when push comes to shove you can kick out to raw SQL without much fuss.

(This is a great example of what I call ["layering"](https://grugbrain.dev/#grug-on-apis) an API.)

But that's not all the Active Record objects are good at: they also provide excellent functionality for building HTML
in the [view layer](https://guides.rubyonrails.org/action_view_overview.html) of Rails.  They don't include *HTML specific* functionality, but they do offer functionality 
that is useful on the view side, such as providing an API to retrieve error messages, even at the field level.

When you are writing Ruby on Rails applications you simply pass your Active Record instances out to the view/templates.

Compare this with a more heavily factored implementation, where validation errors are handled as their own "concern". 
Now you need to pass (or at least access) two different things in order to properly generate your HTML.  It's not 
uncommon in the Java community to adopt the [DTO](https://www.baeldung.com/java-dto-pattern) pattern and have another set of objects entirely
distinct from the ORM layer that is passed out to the view.

I like the Active Record approach.  It may not be [separating concerns](https://en.wikipedia.org/wiki/Separation_of_concerns)
when looked at from a purist perspective, but *my* concern is often getting data from a database into an HTML document,
and Active Record does that job admirably without me needing to deal with a bunch of other objects along the way.

This helps me minimize the total number of objects I need to deal with in the system.

Will some functionality creep into a model that is maybe a bit "view" flavored?

Sure, but that's not the end of the world, and it reduces the number
of layers and concepts I have to deal with.  Having one class that handles retrieving data from the database, holding
domain logic and serves as a vessel for presenting information to the view layer simplifies things tremendously for me.

## Conclusion

I've given three examples of my codin' dirty approach:

* I think (some) big functions are good, actually
* I prefer integration tests to unit tests
* I like to keep my class/interface/concept count down

I'm presenting this, again, not to convince _you_ to code the way _I_ code, or to suggest that the way I code is "optimal" in 
any way.

Rather it is to give you, and especially you younger developers out there, a sense that you don't *have* to write code
the way that many thought leaders suggest in order to have a successful software career.

You shouldn't be intimidated if someone calls your code "dirty": lots of very successful software has been written that
way and, if you focus on the [core ideas](https://en.wikipedia.org/wiki/Algorithms_%2B_Data_Structures_%3D_Programs) 
of [software engineering](https://www.web.stanford.edu/~ouster/cgi-bin/book.php), you will likely be successful 
in spite of how "dirty" it is, and maybe even because of it!