05 May
2011

Git Tip: What Did I Just Merge?

As a lead on an open source project, I spend a lot of time merging awesome contributions from our community into our main repo on github. Sadly, some of them are slightly less awesome (rarely but it does happen) and I sometimes need to unpick what happened to understand the problem and give good feedback. Since the project is hosted on Github, this means having some git tricks up my sleeve, and I thought I’d share.

I have the main repo cloned onto my local machine. Before I do anything, I fetch and merge from the origin and then push back to it, so I know my repo is in sync with the github one. Then I fetch the branch I want to merge – usually one that we’ve got a pull request for. To see what’s in the branch:

git log [branch] --not master

This is nice because it doesn’t show what’s in the master branch of this repo but missing from the incoming branch, it just shows me what’s new on this branch.

I can diff and merge at this point, but more than once I’ve merged and then wondered what changes I have in my repo that aren’t in the github one (this is where it is helpful to have fetched from the remote one first). I have the github repo mapped as “origin” as per the excellent documentation so I can just do:

git diff origin/master..HEAD

This shows me the differences that are in my current repo as compared to origin/master, which is the tip of the main repo shown at the version it was when I last fetched it. I particularly use this when I’ve merged someone’s changes in for testing and am wondering quite what was supposed to happen – sometimes just reading the diff beforehand isn’t enough, it’s only when I get the code merged I realise something unexpected is happening!

03 May
2011

New Netbook Feet

I have a small netbook that I use for events, which I’ve had for a few years and keep upgrading with various bits and pieces. This year, all the little rubber feet had dropped off so if you put it on a surface, it kind of slid around, which was annoying. It occurred to me that I’d bought some sugru at Maker Faire this year, so I broke it out and made new feet for my netbook (and a little keyboard where the same thing had happened)

Sugru Feet for Netbook

Sugru is like slightly toxic plasticene when you first get it out of the box, but it sets like strong rubber. In fact it was perfect for this, the finished feet feel securely attached and they’re slightly squishy so they absorb the shock of me typing or the issues of a slightly uneven surface. Perfect!

15 Apr
2011

Script for Database Patching at Deploy Time

I’ve written before about a simple way of patching database versions and there’s a much more comprehensive article from Harrie on TechPortal as well. I often find though that projects with patching strategies are missing the scripts to apply these automatically when the code is deployed, so I thought I’d share mine.

My current project (BiteStats, a simple report of your google analytics data) uses a basic system where there are numbered patches, and a patch_history table with a row for every patch that was run, showing the version number and a timestamp. When I deploy the code to production, I have a script that runs automatically to apply the patches.

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12 Apr
2011

Invalid Protected Resource URL in Pecl_Oauth

I had a funny (funny weird, not funny haha) problem the other day when working with pecl_oauth in PHP to talk to a service. I’d gone through all the handshaking steps, got the acces token and was ready to start talking to the service itself. However when I tried to call OAuth::fetch, I got an error message:

Fatal error: Uncaught exception 'OAuthException' with message 'Invalid protected resource url, unable to generate signature base string'

There are two things to notice about this. The first one is that I should be catching exceptions thrown by this code :) The second is that I could see nothing wrong with my url, http://api.local. It turned out, after some experimentation, that what is missing here is a trailing slash, and if I supply http://api.local/, everything works perfectly nicely! I’m unclear if this is intended functionality or not, but if you see this error message and you’re requesting a URL with no path info, make sure you have a trailing slash.

11 Apr
2011

PDF Presenter

Recently I’ve switched how I prepare and deliver presentations, using LaTeX to mark up the content and producing PDF slides from that. Which is great but I miss having some of the during-presentation functionality of LibreOffice such as a timer and being able to see what’s on the next slide. Happily for me, there’s a PDF Presenter Console on github and it does what I need!

Getting the thing installed was a bit of a puzzle as it has many dependencies (and that’s just the compiler) but I now have it working like a dream on both my laptop and my netbook. I discovered that it didn’t work with my presenter mouse but with a bit of help from a friend, I have a patch for that and now when I’m presenting I see something like this:

You can set which screen show this, and which shows just the main slide, and you can also set what duration the countdown timer should start from. One really key feature is that the timer doesn’t start counting until you advance from the first slide … unlike in open office where I usually put up the title slide during the break before my talk, then have to stop and start the presentation to reset the clock so I’ve got some vague idea of my running time!

So in true open source form, there’s a tool out there already (thanks Jakob, and thanks for responding to my emails!), and I was able to adapt it to my use case, or rather Kevin was able to! I would love to have the presenter console packaged so I could recommend it for more users, but for now I have a great open source solution enabling me to do what I’m good at – delivering content.

07 Apr
2011

Downgrading a PECL Module

Recently I saw some weirdness in an existing application when I upgraded a PECL module that the application depended on. To figure out if that really was the problem, I wanted to downgrade the module to its previous version. There is no opposite command to “upgrade” but you can instruct pecl to install a specific version of a module, using the -f switch to force pecl to overwrite newer modules.

Downgrading Pecl_OAuth

For me the problems were caused in the switch between default functionality in pecl_oauth 1.1.0 (this isn’t a bug, but is correct behaviour according to the OAuth 1 spec, I just had code that expected the old functionality), so I wanted to put my version back to 1.0.0

pecl install -f oauth-1.0.0

It was easy once I stopped looking for an option called “downgrade” or something like that :) In fact you can use this trick to install all kinds of pecl versions, simply refer to the package as [package name]-[version]. By default pecl won’t let you install packages that aren’t marked “stable”, but you can install beta packages by putting “beta” in place of [version].

Hopefully now I’ve written this I’ll remember next time how to do it!

04 Apr
2011

Slide Markup with LaTeX: First Steps

Since starting to create (a large number of) presentations using LaTeX, I’ve been impressed at how easy this is to pick up and also how quick it is to work with marked up content rather than dragging objects around in Impress or equivalent. With that in mind, I thought I’d outline the very basics of the markup (with probably more snippets to follow as I discover them).

Start at the very beginning

First of all, LaTeX templates are fussy things, start with someone else’s outline (for example the one Dave posted, which I use), or one you made earlier. There is some preamble and then the main contents of the presentation go between the \begin{document} and \end{document} bits.

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31 Mar
2011

Summer PHP Conferences

Conference season approaches and in May I’m on a trip to take in two of the most high-profile events in the PHP conference calendar: DPC in Amsterdam (19-21 May) and php|tek in Chicago (24-27 May). The two events have historically been a few weeks apart and I’ve always complained at having all the fun for the year in such a short space of time – but this year the events are literally back-to-back, there are a small number of speakers attending both and we’re pretty much all on the same flight from Amsterdam to Chicago!

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30 Mar
2011

Creating Presentations with LaTeX

This spring/summer, I’m giving quite a few talks at conferences, and I have a number of my own clients that I’m writing new training materials for. That’s a lot of content in total and so, inspired by Dave’s article about LaTeX and powerdot (and with some help from Dave himself!), I’ve started to write my own presentations this way too.

Getting started was a struggle, I’ve never really used anything like it before and if there’s one thing LaTeX doesn’t do well, it’s error messages! The blog post I linked above has a sample presentation in it and I used that as my starting point. The source code goes in a file with a “.tex” suffix, e.g. presentation.tex. I then installed the texlive-latex-extra, latexmk, vim-latexsuite, latex-fonts-recommended and texlive-fonts-extra packages from aptitude, and generated a PDF by running:

latexmk -f -pdfps presentation.tex

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