devblog

OS X: replace tabs with spaces in all files using expand

Mon, 12 Dec 2011 16:27:00 +0000

We use four spaces (a.k.a. soft tabs) to indent our PHP files. If an errant developer has unknowingly used tabs, you can use expand to replace tabs with spaces across an entire project.

https://gist.github.com/1468061

PHP: removing zero values from an array

Wed, 13 Apr 2011 12:01:00 +0100

If you call array_filter without a callback function, it’ll remove all array elements that evaluate to false (including zeroes).

$numbers = array(0, 1, 2, 0);
echo array_filter($numbers);

Produces:

array(1,2);

PHP: returning an array of single attributes from an array of objects

Wed, 13 Apr 2011 11:49:00 +0100

I miss Ruby’s shorthand collect method to return an array of single attributes:

animals.collect(&:name)

…so I’ve created a (less elegant) equivalent for PHP.

class ArrayExtensions
{
    /**
     * From an array of objects, create a new array containing only 
     * a single attribute of each object
     * 
     * Similar to array.collect(&:attribute) in Ruby
     */
    public static function collect_by_attribute($attribute, $array_of_objects)
    {
        if (!is_array($array_of_objects))
        {
            return array();
        }

        $output = array();

        foreach ($array_of_objects as $object)
        {
            if (is_object($object) && isset($object->$attribute))
            {
                $output[] = $object->$attribute;
            }
        } 
        
        return $output;
    }
}

Use it like this:

$colours = ArrayExtensions::collect_by_attribute('colour', $animals);

…and you’ll get a simple array containing just the attribute you’ve specified:

array('brown', 'blue', 'green')

Update

If you happen to be using PHP ActiveRecord, they have a function called collect that will accomplish the same thing.

$colours = ActiveRecord\collect($animals, 'colour');

PHP: check if a PEAR class is installed

Tue, 22 Mar 2011 15:32:00 +0000

You can’t use file_exists because it doesn’t search the include path.

fopen has a third argument that will check the include path, though:

if (@fopen('Log.php', 'r', true)) 
{   
  echo 'It exists!'; 
}

Redirect the output of a command to a file when using sudo

Thu, 19 Aug 2010 16:49:11 +0100

Rather than > or », use tee.

Redirecting the output of commands run with sudo requires a different approach. For instance consider sudo ls > /root/somefile will not work since it is the shell that tries to write to that file. You can use ls | sudo tee -a /root/somefile to append, or ls | sudo tee /root/somefile to overwrite contents.

From https://help.ubuntu.com/community/RootSudo

Subversion branching best practice

Mon, 02 Aug 2010 15:39:09 +0100

Most new code is checked into the trunk. In general, our developers try to never “break the tree”. Anyone who checks in code which causes the trunk builds to fail will be the recipient of heaping helpings of trash talk and teasing until he gets it fixed. The trunk should always build, and as much as possible, the resulting build should always work. Most new code is checked into the trunk. The trunk is the place where active development of new features is happening. The trunk could be described as “basically unstable”. In our situation, the stability of the trunk build fluctuates over the months during our development cycle. During the early and middle parts of a development cycle, the trunk is often not very stable at all. As we approach alpha, beta and final release, things settle down and the trunk gets more and more stable. At the moment of release, a branch gets created. This branch becomes our maintenance tree for that release. Our current maintenance branch is called “3.0”, since that’s the current major version number of our product. When we need to do a bug fix or patch release, it is done in the maintenance branch. Each time we do a release out of the maintenance branch (like 3.0.2), we apply a tag. After the maintenance branch is created, the trunk once again becomes “basically unstable”. Developers start adding the risky code changes we didn’t want to include in the release. New feature work begins. The cycle starts over and repeats itself.

From http://www.ericsink.com/scm/scm_branches.html

List your Apache virtual hosts

Fri, 21 May 2010 14:48:15 +0100

apache2ctl -t -D DUMP_VHOSTS

Copy a large directory of files using ls and xargs

Thu, 13 May 2010 16:00:14 +0100

ls . | xargs -i -t cp ./{} /path/to/new/directory

See example 12-6 at http://www.homepage.montana.edu/~unixuser/051905/abs-guide/moreadv.html

Rails migrations: creating a MySQL BIGINT

Wed, 07 Apr 2010 16:56:35 +0100

add_column :facebook_user_id, :integer, :limit => 8 # BIGINT

Basic use of 'screen'

Thu, 25 Feb 2010 16:25:40 +0000

Using screen is a great way to leave long-running processes churning away when you’re not logged into the machine.

Open a new screen

screen

Detach from the screen

This does not interrupt whatever is running in the screen. Press Ctrl-A then D.

Reattach to a screen you’ve already opened

screen -r

If you’ve opened multiple screens, a list will be displayed:

There are several suitable screens on:
	1681.ttys004.braeburn	(Detached)
	1686.ttys004.braeburn	(Detached)

Just use the process ID of the screen to resume the right one:

screen -r 1681

Change your default SSH username

Fri, 12 Feb 2010 17:09:09 +0000

If you’ve not had your own choice of username on your machine (for example, if your company imposes a username policy), you can set up a different default username for SSH in ~/.ssh/config:

Host *
  User chris

Readable, colourful Terminal in Snow Leopard

Wed, 27 Jan 2010 20:15:00 +0000

Install SIMBL: http://www.culater.net/software/SIMBL/SIMBL.php
Install the Snow-Leopard-friendly version of the TerminalColors plugin for SIMBL: http://github.com/timmfin/terminalcolours
Install the IR_Black theme and set it as default in Terminal.app preferences: http://blog.infinitered.com/entries/show/6
Turn on CLI color in your .bash_profile:
```
export CLICOLOR=1;
```
Bonus round: set yourself a colourful bash prompt: http://devblog.bluefuton.com/2008/05/coloured-bash-prompt-in-os-x/

Border radius in Chrome, Firefox and Safari

Mon, 07 Dec 2009 15:47:23 +0000

Chrome 4 currently appears to be the only browser to implement the W3C’s border-radius property: http://www.w3.org/TR/2002/WD-css3-border-20021107/#the-border-radius

border-top-left-radius: 1em;
border-top-right-radius: 1em;

You can produce the same result using proprietary attributes in Firefox 3.5 and Safari 4:

/* Firefox */
-moz-border-radius-topleft: 1em;
-moz-border-radius-topright: 1em;

/* Safari */
-webkit-border-top-left-radius: 1em;
-webkit-border-top-right-radius: 1em;

Source: http://www.css3.info/preview/rounded-border/

Using find with -exec to copy large directories

Tue, 13 Oct 2009 20:38:16 +0100

To copy files from one directory, you might usually do:

cp dir/* anotherdir/

If you try to do this with a particular large number of files, you may encounter the ‘argument list too long’ error. In this case you can use:

find . -exec cp {} /path/to/anotherdir/ \;

More approaches at: http://www.linuxjournal.com/article/6060

FOWA 2009: The Future of HTML5

Tue, 13 Oct 2009 17:42:32 +0100

“The web is too important for society to be in the hands of any one vendor”

- Bruce Lawson, Opera HTML5 is more a collection of new technologies than a single new standard - we can start using parts of it today. You can use Moderizr to check what HTML5/CSS3 features are available in your browser. You can see it in action at FindMeByIP.

Canvas/SVG

Cross-browser canvas support & speed Canvas is possible in IE using a single script tag: check out Excanvas Filament have created accessible charts from HTML tables using the canvas element: jQuery Visualise plugin

Accessibility: canvas or SVG?

With images off, canvas elements are essentially blank, whereas SVG remains as text
Use SVG for content and canvas for bling (for now)

Forms

Browser handles special field display and front-end validation that has traditionally required Javascript (popup calendar, focus on field, email validation, required field validation). Examples: http://people.opera.com/brucel/demo/html5-forms-demo.html

Geolocation

Currently iPhone Safari and Firefox 3.5 only. Examples: http://html5demos.com/geo

Linux: email alert when disk is nearly full

Wed, 30 Sep 2009 22:23:00 +0100

#!/bin/bash
# Send an email when disk space used reaches a certain threshold
FS="/"
SERVER_NAME="linux02"
EMAIL="user@example.com"
THRESHOLD=95
OUTPUT=($(LC_ALL=C df -P ${FS}))
CURRENT=$(echo ${OUTPUT[11]} | sed 's/%//')
[ $CURRENT -gt $THRESHOLD ] && df -h | mail -s "$SERVER_NAME disk space alert: $CURRENT% full" $EMAIL

I’ve set this up as a cron job run at 3am daily:

0 3 * * * ./root/maintenance/check_free_space.sh

Based upon http://www.cyberciti.biz/faq/mac-osx-unix-get-an-alert-when-my-disk-is-full/

Is IE rendering in quirks mode?

Fri, 11 Sep 2009 17:27:30 +0100

To find out, load the page in question and then paste this into your address bar:

javascript:alert(document.compatMode);

‘backCompat’ is quirks mode; ‘css1Compat’ is standards mode. More info on quirks mode: http://www.quirksmode.org/css/quirksmode.html

Configuring the viewport on iPhone and iPod Touch

Tue, 04 Aug 2009 21:26:37 +0100

By default, Mobile Safari assumes that the page is 980px wide and sizes the viewport accordingly. If your page is significantly smaller, you can use the viewport meta tag to configure the viewport dimensions. For example:

Detailed documentation is available at developer.apple.com. In portrait mode, the viewport is 320px wide; in landscape mode, it’s 480px wide.

Apache: rewriting requests for iPhone and iPod Touch

Tue, 04 Aug 2009 21:20:39 +0100

This snippet will rewrite all requests to the page iphone.html when viewed on iPhone or iPod Touch. Requests for .gif and .css files are not rewritten, so you can include stylesheets and images in your iPhone-specific page.

RewriteEngine On
RewriteCond %{HTTP_USER_AGENT} .*Mobile.*Safari
RewriteRule !\.(gif|css)$ /iphone.html  [L]

Source: http://webdirect.no/mobile/apache-rewrite-rule-for-iphone-users/

Find files created in the last x minutes

Fri, 31 Jul 2009 16:46:35 +0100

To find files created in the last 30 minutes:

find -cmin +30