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Symbolic Forest

A homage to loading screens.

Blog : Posts tagged with ‘coding’

We can rebuild it! We have the technology! (part four)

Or, finishing off the odds and ends

Settling down to see what else I should write in the series of posts about how I rebuilt this website, I realised that the main issues now have already been covered. The previous posts in this series have discussed the following:

And throughout the last two, we touched on some other important software engineering topics, such as refactoring your code so that you Don’t Repeat Yourself, and optimising your code when it’s clear that (and where) it is needed.

There are a few other topics to touch on, but I wasn’t sure they warranted a full post each, so this post is on a couple of those issues, and any other odds and ends that spring to mind whilst I am writing it.

Firstly, the old blog was not at all responsive: in web front-end terms, that means it didn’t mould itself to fit the needs of the users and their devices. Rather, it expected the world to all use a monitor the same size as mine, and if they didn’t, then tough. When I wrote the last designs the majority of the traffic the site was receiving was from people on regular computers; nowadays, that has changed completely.

However, the reason that this isn’t a particularly exciting topic to write about is that I didn’t learn any new skills or dive into interesting new programming techniques. I went the straightforward route, installed Bootstrap 4.5, and went from there. Now, I should say, using Bootstrap doesn’t magically mean your site will become responsive overnight; in fact, it’s very straightforward to accidentally write an entirely non-responsive website. Responsiveness needs carefully planning. However, with that careful planning, and some careful use of the Bootstrap CSS layout classes, I achieved the following aims:

  • The source code is laid out so that the main content of the page always comes before the sidebars in the code, wherever the sidebars are actually displayed. This didn’t matter so much on this blog, but on the Garden Blog, which on desktop screens has sidebars on both sides of the page, it does need to be specifically coded. Bootstrap’s layout classes, though, allow you to separate the order in which columns appear on a page from the order in which they appear in the code.
  • More importantly, the sidebars move about depending on page width. If you view this site on a desktop screen it has a menu sidebar over on the right. On a narrow mobile screen, the sidebar content is down below at the bottom of the page.
  • The font resizes based on screen size for easier reading on small screens. You can’t do this with Bootstrap itself; this required @media selectors in the CSS code with breakpoints chosen to match the Bootstrap ones (which, fortunately, are clearly documented).
  • Content images (as opposed to what you could call “structural images”) have max-width: 100%; set. Without this, if the image is bigger than the computed pixel size of the content column, your mobile browser will likely rescale things to get the whole image on screen, so the content column (and the text in it) will become too narrow to read.

On the last point, manual intervention is still required on a couple of types of content. Embedded YouTube videos like in this post need to have the embed code manually edited, and very long lines of text without spaces need to have soft hyphens or zero-width spaces inserted, in order to stop the same thing happening. The latter usually occurs in example code, where zero-width spaces are more appropriate than soft hyphens. All in all though, I’ve managed to produce something that is suitably responsive 95% of the time.

The other point that is worth writing about is the build process of the site. As Wintersmith is a static site generator, every change to the site needs the static files to be built and deployed. The files from the previous version need to be deleted (in case any stale ones, that have disappeared completely from the latest iteration of the output, are still lying about) and then Wintersmith is run to generate the new version. You could do this very simply with a one-liner: rm -rf ../../build/* && wintersmith build if you’re using Bash, for example. However, this site actually consists of three separate Wintersmith sites in parallel. The delete step might only have to be done once, but doing the build step three separate times is a pain. Moreover, what if you only want to delete and rebuild one of the three?

As Wintersmith is a JavaScript program, and uses npm (the Node Package Manager) for managing its dependencies, it turns out that there’s an easy solution to this. Every npm package or package-consumer uses a package.json file to control how npm works; and each package.json file can include a scripts section containing arbitrary commands to run. So, in the package.json file for this blog, I inserted the following:

"scripts": {
  "clean": "node ../shared/js/unlink.js ../../build/blog",
  "build": "wintersmith build"
}

You might be wondering what unlink.js is. I said before that “if you’re using Bash” you could use rm -rf ../../build. However, I develop on a Windows machine, and for this site I use VS Code to do most of the writing. Sometimes therefore I want to build the site using PowerShell, because that’s the default VS Code terminal. Sometimes, though, I’ll be using GitBash, because that’s convenient for my source control commands. One day I might want to develop on a Linux machine. One of the big changes between these different environments is how you delete things: del or Remove-Item in PowerShell; rm in Bash and friends. unlink.js is a small script that reproduces some of the functionality of rm using the JavaScript del package, so that I have a command that will work in the same way across any environment.

So, this means that in the main blog’s folder I can type npm run clean && npm run build and it will do just the same thing as the one-liner command above (although note that the clean step only deletes the main blog’s files). In the other Wintersmith site folders, we have a very similar thing. Then, in the folder above, we have a package.json file which contains clean and build commands for each subsite, and a top-level command that runs each of the others in succession.

"scripts": {
  "clean:main": "cd main && npm run clean",
  "clean:misc": "cd misc && npm run clean",
  "clean:garden": "cd garden && npm run clean",
  "clean": "npm run clean:misc && npm run clean:main && npm run clean:garden",
  "build:main": "cd main && npm run build",
  "build:misc": "cd misc && npm run build",
  "build:garden": "cd garden && npm run build",
  "build": "npm run build:misc && npm run build:main && npm run build:garden"
}

And there you have it. By typing npm run clean && npm run build at the top level, it will recurse into each subsite and clean and build all of them. By typing the same command one folder down, it will clean and build that site alone, leaving the others untouched.

When that’s done, all I have to do is upload the changed files; and I have a tool to do that efficiently. Maybe I’ll go through that another day. I also haven’t really touched on my source-control and change management process; and all I have to say there is, it doesn’t matter what process you use, but you will find things a lot more straightforward if you find a process you like and stick to it. Even if you’re just a lone developer, using a sensible source control workflow and release process makes life much easier and makes you less likely to make mistakes; you don’t need anything as rigid as a big commercial organisation, but just having a set process for storing your changes and releasing them to the public means that you are less likely to slip up and make mistakes. This is probably something else I’ll expand into an essay at some point.

Is the site perfect now? No, of course not. There are always more changes to be made, and more features to add; I haven’t even touched on the things I decided not to do right now but might bring in one day. Thoe changes are for the future, though. Right now, for a small spare-time project, I’m quite pleased with what we have.

We can rebuild it! We have the technology! (part three)

Introducing Pug

If you want to start reading this series of articles from the start, the first part is here. In the previous part we discussed how I adapted Wintersmith to my purposes, adding extra page generators for different types of archive page, and refactoring them to make sure that I wasn’t repeating the same logic in multiple places, which is always a good process to follow on any sort of coding project. This post is about the templating language that Wintersmith uses, Pug. When I say “that Wintersmith uses”, incidentally, you should always add a “by default” rider, because as we saw previously adding support for something else generally wouldn’t be too hard to do.

In this case, though, I decided to stick with Pug because rather than being a general-purpose templating or macro language, it’s specifically tailored towards outputting HTML. If you’ve ever tried playing around with HTML itself, you’re probably aware that the structure of an HTML document (or the Document Object Model, as it’s known) has to form a tree of elements, but also that the developer is responsible for making sure that it actually is a valid tree by ending elements in the right order. In other words, when you write code that looks like this:

<section><article><h2>Post title</h2><p>Some <em>content</em> here.</p></article></section>

it’s the developer who is responsible for making sure that those </p>, </article> and </section> tags come in the right order; that the code ends its elements in reverse order to how they started. Because HTML doesn’t pay any attention to (most) white space, they have to be supplied. Pug, on the other hand, enforces correct indentation to represent the tree structure of the document, meaning that you can’t accidentally create a document that doesn’t have a valid structure. It might be the wrong structure, if you mess up your indentation, but that’s a separate issue. In Pug, the above line of HTML would look like this:

section
  article
    h2 Post title
    p Some
      em content
      | here.

You specify the content of an element by putting it on the same line or indenting the following line; elements are automatically closed when you reach a line with the same or less indentation. Note that Pug also assumes that the first word on each line will be an opening tag, and how we can suppress this assumption with the | symbol. You can supply attributes in brackets, so an <a href="target"> ... </a> element becomes a(href="target") ..., and Pug also has CSS-selector-style shortcuts for the class and id attributes, because they’re so commonly used. The HTML code

<section class="mainContent"><article id="post-94">...</article></section>

becomes this in Pug:

section.mainContent
  article#post-94 ...

So far so good; and I immediately cracked on with looking at the pages of the old Wordpress blog and converting the HTML of a typical page into Pug. Moreover, Pug also supports inheritance and mixins (a bit like functions), so I could repeat the exercise of refactoring common code into a single location. The vast majority of the template code for each type of page sits in a single layout.pug file, which is inherited by the templates for specific types of page. It defines a mixin called post() which takes the data structure of a single post as its argument and formats it. The template for single posts is reduced to just this:

extends layout
block append vars
  - subHeader = '';
block append title
  | #{ ' : ' + page.title }
block content
  +post(page)

The block keyword is used to either append to or overwrite specific regions of the primary layout.pug template. The content part of the home page template is just as straightforward:

extends layout
block content
  each article in articles
    +post(article)

I’ve omitted the biggest part of the home page template, which inserts the “Newer posts” and “Older posts” links at the bottom of the page; you can see though that for the content block, the only difference is that we iterate over a range of articles—chosen by the page generator function—and call the mixin for each one.

The great thing about Pug, though, is that it lets you drop out into JavaScript at any point to run bits of code, and when doing that, you don’t just have access to the data for the page it’s working on, you can see the full data model of the entire site. So this makes it easy to do things such as output the sidebar menus (I say sidebar; they’re at the bottom if you’re on mobile) with content that includes things like the number of posts in each month and each category. In the case of the tag cloud, it effectively has to put together a histogram of all of the tags on every post, which we can only do if we have sight of the entire model. It’s also really useful to be able to do little bits of data manipulation on the content before we output it, even if it’s effectively little cosmetic things. The mixin for each post contains the following Javascript, to process the post’s categories:

- if (!Array.isArray(thePost.metadata.categories)) thePost.metadata.categories = [ thePost.metadata.categories ]
- thePost.metadata.categories = Array.from(new Set(thePost.metadata.categories))

The - at the start of each line tells Pug that this is JavaScript code to be run, rather than template content; all this code does is tidy up the post’s category data a little, firstly by making sure the categories are an array, and secondly by removing any duplicates.

You can, however, get a bit carried away with the JavaScript you include in the template. My first complete design for the blog, it turned out, took something like 90 minutes to 2 hours to build the site on my puny laptop; not really helpful if you just want to knock off a quick blog post and upload it. That’s because all of the code I had written to generate the tag cloud, the monthly menus and the category menus, was in the template, so it was being re-computed over again for each page. If you assume that the time taken to generate all those menus is roughly proportional to the number of posts on the blog, O(n) in computer science terms (I haven’t really looked into it—it can’t be any better but it may indeed be worse) then the time taken to generate the whole blog becomes O(n2), which translates as “this doesn’t really scale very well”. The garden blog with its sixtyish posts so far was no problem; for this blog (over 750 posts and counting) it wasn’t really workable.

What’s the solution to this? Back to the Wintersmith code. All those menus are (at least with the present design) always going to contain the same data at any given time, so we only ever need to generate them once. So, I created another Wintersmith plugin, cacher.coffee. The JavaScript code I’d put into my layout templates was converted into CoffeeScript code, called from the plugin registration function. It doesn’t generate HTML itself; instead, it generates data structures containing all of the information in the menus. If you were to write it out as JSON it would look something like this:

"monthData": [
  { "url": "2020/10/", "name": "October 2020", "count": 4 },
  { "url": "2020/09/", "name": "September 2020", "count": 9 },
  ...
],
"categoryData": [
  { "name": "Artistic", "longer": "Posts categorised in Artistic", "count": 105 },
  ...
],
"tagData": [
  { "name": "archaeology", "count": 18, "fontSize": "0.83333" },
  { "name": "art", "count": 23, "fontSize": "0.97222" },
  ...
]

And so on; you get the idea. The template then just contains some very simple code that loops through these data structures and turns them into HTML in the appropriate way for each site. Doing this cut the build time down from up to two hours to around five minutes. It’s still not as quick to write a post here as it is with something like Wordpress, but five minutes is a liveable amount of overhead as far as I am concerned.

The Plain People Of The Internet: So, you’re saying you got it all wrong the first time? Wouldn’t it all have been fine from the start if you’d done it that way to begin with?

Well, yes and no. It would have been cleaner code from the start, that’s for certain; the faster code also has a much better logical structure, as it keeps the code that generates the semantic content at arm’s length from the code that handles the visual appearance, using the data structure above as a contract between the two. Loose coupling between components is, from an architectural point of view, nearly always preferable than tight coupling. On the other hand, one of the basic principles of agile development (in all its many and glorious forms) is: don’t write more code than you need. For a small side project like this blog, the best course of action is nearly always to write the simplest thing that will work, be aware than you’re now owing some technical debt, and come back to improve it later. The difficult thing in the commercial world is nearly always making sure that that last part actually happens, but for a site like this all you need is self-discipline and time.

That just about covers, I think, how I learned enough Pug to put together the templates for this site. We still haven’t covered, though, the layout itself, and all the important ancillary stuff you should never gloss over such as the build-deploy process and how it’s actually hosted. We’ll make a start on that in the next post in this series.

The next post in this series, in which we discuss responsive design, and using npm to make the build process more straightforward, is here

We can rebuild it! We have the technology! (part two)

In which we delve into Wintersmith and some CoffeeScript

Previously, I discussed some various possible ways to structure the coding of a website, and why I decided to rebuild this site around the static site generator Wintersmith. Today, it’s time to dive a little deeper into what that actually entailed. Don’t worry if you’re not a technical reader; I’ll try to keep it all fairly straightforward.

To produce this website using Wintersmith, there were essential four particular technologies I knew I’d need to know. Firstly, the basics: HTML and CSS, as if I was writing every single one of the four-thousand-odd HTML files that currently make up this website from scratch. We’ll probably come onto that in a later post. Second-and-thirdly, by default Wintersmith uses Markdown to turn content into HTML, and Pug as the basis for its page templates. Markdown I was fairly familiar with as it’s so widely used; Pug was something new to me. And finally, as I said before, Wintersmith itself is written using CoffeeScript. I was vaguely aware that, out of the box, Wintersmith’s blog template wouldn’t fully replicate all of Wordpress’s features and I’d probably need to extend it. That would involve writing code, and when you’re extending an existing system, it’s always a good idea to try to match that system’s coding style and idioms. However, I’d come across CoffeeScript briefly a few years ago, and if you’ve used JavaScript, CoffeeScript is fairly straightforward to comprehend.

The Plain People Of The Internet: Hang on a minute there, now! You told us up there at the top, you were going to keep all this nice and straightforward for us non-technical Plain People. This isn’t sounding very non-technical to us now.

Ah, but I promised I would try. And look, so far, all I’ve done is listed stuff and told you why I needed to use it.

The Plain People Of The Internet: You’re not going to be enticing people to this Wintersmith malarkey, though, are you? Us Plain People don’t want something that means we need to learn three different languages! We want something nice and simple with a box on-screen we can write words in!

Now, now. I was like you once. I didn’t spring into life fully-formed with a knowledge of JavaScript and an instinctive awareness of how to exit Vim. I, too, thought that life would be much easier with a box I could just enter text into and that would be that. The problem is, I’m a perfectionist and I like the site to look just right, and for that you need to have some knowledge of HTML, CSS and all that side of things anyway. If you want your site to do anything even slightly out-of-the-ordinary, you end up having to learn JavaScript. And once you know all this, and you’re happy you at least know some of it, then why not go the whole hog and start knocking together something with three different programming languages you only learned last week? You’ll never know unless you try.

The Plain People Of The Internet: Right. You’re not convincing me, though.

Well, just stick with it and we’ll see how it goes.

In any case, I had at least come across CoffeeScript before at work, even if I didn’t use it for very much. It went through a phase a few years ago, I think, of almost being the next big language in the front-end space; but unlike TypeScript, it didn’t quite make it, possibly because (also unlike TypeScript) it is just that bit too different to JavaScript and didn’t have quite so much energy behind it. However, it is essentially just a layer on top of JavaScript, and everything in CoffeeScript has a direct JavaScript equivalent, so even if the syntax seems a bit strange at points it’s never going to be conceptually too far away from the way that JavaScript handles something. The official website goes as far as to say:

Underneath that awkward Java-esque patina, JavaScript has always had a gorgeous heart. CoffeeScript is an attempt to expose the good parts of JavaScript in a simple way.

Now if you ask me, that’s going a little bit far; but then, I don’t mind the “Java-esque patina” because the C-derived languages like C# and Java are the ones I’m happiest using anyway. CoffeeScript brings Python-style whitespace-significance to JavaScript: in other words, whereas in JavaScript the empty space and indentation in your code is just there to make it look pretty, in CoffeeScript it’s a significant part of the syntax. My own feeling on this, which might be controversial, is that the syntax of CoffeeScript is harder to read than the equivalent JavaScript. However, despite what some people will tell you, there’s no such thing as an objective viewpoint when it comes to language syntax; and as I said above, as Wintersmith is written in CoffeeScript, the best language to use to change and extend its behaviour is also CoffeeScript.

Wintersmith, indeed, is designed for its behaviour to be changeable and extendable. By default it only has a fairly small set of capabilities. It takes a “content tree”, a particular set of files and folders, and a set of templates. Markdown files in the content tree are converted to HTML, merged with a template, and written to an output file. JSON files are treated in almost the same way, almost as content files without any actual content aside from a block of metadata. Other filetypes, such as images, are copied through to the output unchanged. So, to take this article you’re reading as an example: it started out as a file called articles/we-can-rebuild-it-we-have-the-technology-part-two/index.md. That file starts with this metadata block, which as is normal for Markdown metadata, is in YAML:

---
title: We can rebuild it! We have the technology! (part two)
template: article.pug
date: 2020-09-28 20:09:00
...
---

I’ve configured Wintersmith to use a default output filename based on the date and title in the metadata of each article. This file, therefore, will be merged with the article.pug template and output as 2020/09/28/we-can-rebuild-it-we-have-the-technology-part-two/index.html, so its URI will nicely match the equivalent in Wordpress. So there you go, we have a page for each blog post, almost right out of the box.

That’s fine for individual article pages, but what about the home page of the blog? Well, Wintersmith is designed to use plugins for various things, including page generation; and if you create a new Wintersmith site using its blog template, you will get a file called paginator.coffee added to your site’s plugins folder, plus a reference in the site configuration file config.json to make sure it gets loaded.

"plugins": [
    "./plugins/paginator.coffee"
]

The code in paginator.coffee defines a class called PaginatorPage, which describes a page consisting of a group of articles. It then calls a Wintersmith API function called registerGenerator, to register a generator function. The generator function looks over every article in the content/articles folder, slices them up into blocks of your favoured articles-per-page value, and creates a PaginatorPage object for each block of articles. These are then output as index.html, page/2/index.html, page/3/index.html and so on. There, essentially, is the basis of a blog.

If you’ve used something like Wordpress, or if you’re a regular reader of this site, you’ll know most blogs have a bit more to them than that. They have features to categorise and file articles, such as categories and tags, and they also have date-based archives so it’s easy to, say, go and read everything posted in May 2008 or any other arbitrary month of your choice. Well, I thought, that’s straightforward. All we have to do there is to reuse the paginator.coffee plugin, and go in and fiddle with the code. So, I copied the logic from paginator.coffee and produced categoriser.coffee, archiver.coffee and tagulator.coffee to handle the different types of archive page. Pure copy-and-paste code would result in a lot of duplication, so to prevent that, I also created an additional “plugin” called common.coffee. Any code that is repeated across more than one of the page-generator plugins was pulled out into a function in common.coffee, so that then it can be called from anywhere in the generator code that needs it. Moreover, this blog and the garden blog are structured as separate Wintersmith sites, so I pulled out all of the CoffeeScript code (including the supplied but now much-altered paginator.coffee) into a separate shared directory tree, equally distant from either blog. The plugins section of the configuration file now looked like this:

"plugins": [
    "../shared/wintersmith/plugins/common.coffee",
    "../shared/wintersmith/plugins/paginator.coffee",
    "../shared/wintersmith/plugins/categoriser.coffee",
    "../shared/wintersmith/plugins/tagulator.coffee",
    "../shared/wintersmith/plugins/archiver.coffee"
]

The original paginator page generation function has now turned into the below: note how the only logic here is that which slices up the list of articles into pages, because everything else has been moved out into other functions. The getArticles function weeds out any maybe-articles that don’t meet the criteria for being an article properly, such as not having a template defined.

env.registerGenerator 'paginator', (contents, callback) ->
  articles = env.helpers.getArticles contents
  numPages = Math.ceil articles.length / options.perPage
  pages = []
  for i in [0...numPages]
    pageArticles = articles.slice i * options.perPage, (i + 1) * options.perPage
    pages.push new PaginatorPage i + 1, numPages, pageArticles
  env.helpers.pageLinker pages
  rv = env.helpers.addPagesToOutput pages, 'default'
  callback null, rv

This is the simplest of all the page-generators: the others have slightly more complex requirements, such as creating a fake “Uncategorised posts” category, or labelling the archive page for January 1970 as “Undated posts”.

There we go: my Wintersmith installations are now reproducing pretty much all of the different types of archive that Wordpress was handling dynamically for me before. The next time I come back to this topic, we’ll move onto the template side of things, including some nasty performance issues I found and then sorted out along the way.

The next part of this post, in which we discuss website templating using Pug, is here

Interconnectedness

In which pulling on one thread untangles a whole mass of knots

Most of the intractable problem I was slowly chipping away at at work was solved, today. I suddenly realised that the vast majority of all my unsolved problems - and another, urgent problem, that an outside contractor had asked me for help with - were in all likelihood all just different facets of the same thing. It wasn’t, it turned out, the sole cause of all of them, but it was enough of a hint to clear most of them and give me the boost of encouragement I needed to sort out the rest.

I don’t mean to bang on about the weather, but I’ve been warily watching the forecast all day today. On Saturday I’m due to go and work on the railway, and to get there I have to drive 90 miles ending in a good mile of steep, twisty country lane. Saturday is forecast snow. I really don’t fancy driving there in that weather, and I definitely don’t fancy the risk of getting there, the snow starting, and being unable to get home again. Still, even if it does snow, it should be too warm and wet for the snow to stick.

Disassembly, Reassembly

In which we try to use metaphor

The past two days at work have largely just been the long slog of writing unit tests for a part of the system which firstly, was one of the hairiest and oldest parts of the system; and secondly, I’ve just rewritten from scratch. In its non-rewritten form it was almost entirely impossible to test, due to its reliance on static code without any sort of injection.

For non-coding people for whom this is all so much “mwah mwah mwah” like the adults in Peanuts: a few weeks ago I was doing some interesting work, to whit, dismantling a creaking horror, putting its parts side by side on the workbench, scraping off the rust and muck and polishing them up, before assembling the important bits back together into a smoother, leaner contraption and throwing away all the spare screws, unidentifiable rusted-up chunks and other bits that didn’t seem to do anything. Now, though, I have the job of going through each of the newly-polished parts of the machine and creating tools to prove that they do what I think they were originally supposed to do. As the old machine was so gummed-up and tangled with spiderwebs and scrags of twine, it was impossible to try to do this before, because trying to poke one part would have, in best Heath Robinson style, accidentally tugged on the next bit and pushed something else that was supposed to be unconnected, setting off a ball rolling down a ramp to trip a lever and drop a counterweight to hit me on the head in the classic slapstick manner. All this testing each aspect of the behaviour of each part of the device is, clearly, a very important task to do, but it’s also a very dull job. Which is why an awful lot of coders don’t like to do it properly, or use it as a “hiding away” job to avoid doing harder work.

Nevertheless, today it did lead me to find one of those bugs which is so ridiculous it made me laugh, so ridiculous that you have a “it can’t really be meant to work like that?” moment and have to dance around the room slightly. I confirmed with the team business analyst that no, the system definitely shouldn’t behave the way the code appeared to. I asked the team maths analyst what he thought, and he said, “actually, that might explain a few things.”