Book review: Pro Git by Scott Chacon

Like many others, I use git as a version control system for my Lisp code. Version control is one of those things that offer a lot of benefits with relatively little investment: I picked up a few basic git commands from tutorials on the internet (Github has a nice collection), but didn't bother to learn about git in depth.

However, as others started to contribute to my libraries, I was forced to learn more about certain features, most importantly branching and merging. After spending a few hours doing things the wrong way, I realized that I need to do some reading, and I was lucky to find Pro Git by Scott Chacon, one of the prominent git developers. Thanks to the author and the publisher (Apress), the book is available online. I really appreciate that Apress makes its books available online so I can start reading them immediately, and I have already ordered a dead tree copy.

The book is a pleasure to read, and is really useful. Instead of simply rehashing the manual, it focuses on explaining the concepts of git, and illustrates them with typical workflows. I found this invaluable: understanding the concepts behind git made me realize that I have been doing things the wrong way. I used subversion before, and it was still influencing the way I use git. For example, branching in git is really, really cheap, and I learned that I should do it more often.

My favorite chapters from this book are Git Branching, which explains the concept of branches, gives examples of basic branching and merging, branch management and typical workflows, and also discusses remote branches, and Distributed Git, which talks about distributed workflows in more detail.

I have learned a lot from this book, and hopefully it will help me manage my Lisp libraries better. So far I have been keeping changes on my hard disk between "releases" (updates to master), but now I think that I will make development branches for new features and push them more often.

Maxell pendrive suckage

I had to reinstall the OS on my parents' computer during the Christmas holidays. I forgot to bring my external hard disk with me, so I decided to buy a pendrive to backup their files.

Unfortunately, I picked a Maxell Venture to do the job. Maxell puts this pendrive in their Business Range line. I learned about this later because this is not indicated on the packaging. If it had been, I wouldn't have touched the product with a ten-foot pole. I consider pendrives a commodity: they should present a standard interface, and the only qualitative differentiation I can imagine is sleek and/or durable design or novelty packaging (not that I care for the latter).

Apparently, some pendrive manufacturers think otherwise. Maxell decided that it would indulge consumers with "extra features", such as "security and file compression software". Unfortunately, this makes the pendrive interface non-standard. The pendrive shows up as two physical devices, one contains a small partition called SECRET, the other has a large partition called PUBLIC. Apparently, this feature is governed by the firmware. There is no way to repartition the device (which shows up as /dev/sdb and /dev/sdc at the same time), and it is impossible to get rid of these "features". An added bonus is that I found it impossible to make this pendrive boot: the BIOS of my computer was understandably confused about this whole arrangement.

Nice job, Maxell. I returned the pendrive to the store the next day. When I googled for a possible solution, I learned about a similar "extension" called U3, which is equally useless but at least it can be removed (albeit only using Windows), and the U3 folks are decent enough to offer removal software on their website. By the way, Maxell support still hasn't answered my e-mail.

I think that companies should be free to offer "features" that break pendrives, but they should be obliged by law to display this warning message:

You are purchasing a pendrive with a non-standard interface.
Generally, this sucks.
Do yourself a favor and buy from one of our competitors.

Syntax highlighting with org-mode

Blogging is probably the best way to disseminate information about new (features in) libraries in the Lisp community—if you are reading this, you are probably subscribed to Planet Lisp, which nicely aggregates all Lisp-related blogs that are registered. On the other hand, blogging about Lisp is—or was—quite a hassle to me. I am using Google's blogger.com, which has nice features, but I am used to Emacs and prefer typing text there. Including Lisp code snippets was a pain in the butt: I had to keep playing with <pre> tags and it still didn't look right. But now I had a bit of time to explore the issue and found a workflow that is

1. pretty painless and
2. does syntax highlighting.

It uses org-mode, which I already use to manage my agenda. I would like to thank EMACS-FU, Blogistic Reflections, Drew Crampsie, Ross Lonstein, and Jānis Džeriņš for their help and/or blog posts on using org-mode.

Here is what you should do:

1. In Emacs, set org-export-htmlize-output-type to css. This makes org-mode emit formatting with <span> elements instead of inline style directives, which is the default.
2. Open a source file with org-mode (eg sample.org). Leave it empty, we just need it to generate some CSS. Use the Emacs function org-export (usually C-c C-e), and extract the CSS part. This is the first part of all the CSS styling you need.
3. Generate the second part with org-export-htmlize-generate-css.
4. Paste both parts into the CSS section served by your blog engine. For example, on blogger.com you should go to Layout, then Edit HTML, and paste it after the <Variable name=...> section where the CSS formatting starts. There will be some overlap between the two parts and possibly your existing template, but it should not matter. Edit colors, fonts, etc to the style you want. All I did was change the colors for the <pre> tags.
5. Turn off auto-conversion of line breaks. On blogger.com, you can find Convert line breaks in the Settings/Formatting section. Unless you do this, your blog engine could introduce unnecessary <br/> tags in the HTML.

You are now ready to post. A simple example looks like this in org-mode:

#+TITLE:     Sample blog post
#+AUTHOR:    Your Name
#+EMAIL:     your@email.address
#+LANGUAGE:  en
#+OPTIONS:   H:3 num:nil toc:nil \n:nil @:t ::t |:t ^:t -:t f:t *:tl creator:nil
#+OPTIONS:   TeX:t LaTeX:nil skip:nil d:nil tags:not-in-toc author:nil timestamp:nil
#+INFOJS_OPT: view:nil toc:nil ltoc:t mouse:underline buttons:0 path:http://orgmode.org/org-info.js

Here is some sample source code:
#+BEGIN_SRC lisp
(defun add2 (x)
  (+ x 2))
#+END_SRC
You can include example output:
#+BEGIN_EXAMPLE
CL-USER> (add2 3)
5
#+END_EXAMPLE
See the [[http://orgmode.org/org.html][Org Manual]] for further details.

You can include formatting options as shown in the example.

I use the following snippet in Emacs for settings and keybindings:

(defun org-export-body-as-html ()
  (interactive)
  (org-export-as-html 3 nil nil "blog" t))

(add-hook 'org-mode-hook
          (lambda ()
            (setq org-export-htmlize-output-type 'css)
            (local-set-key (quote [?\C-c ?\C-x]) 'org-export-body-as-html)))