Detect the language of a string
You can use the whatlanguage gem to detect the language of a Ruby string.
Note that it also has not been updated in quite a while and that there might be alternatives. However, it still works.
It has problems with short strings, but works quite well on longer texts.
Use it like this:
>> WhatLanguage.new(:all).language('Half the price of a hotel for twice the space')
=> :english
There is also a convenience method on Strings (you may need to require 'whatlanguage/string').
>> 'Wir ent...
Rails: How to get PostgreSQL version being used
To check the currently running PG version from your Rails application (e.g. Rails console on your production server), simply do this:
ActiveRecord::Base.connection.select_value('SELECT version()')
Middleman does not fingerprint asset paths by default
We're using Middleman for some static sites like our blog.
Despite being very similar to Rails, Middleman does not add a fingerprint hash to its asset paths by default. This means that when you write this:
<%= javascript_include_tag 'all.js' %>
... you always get the same path, regardless of the contents of all.js:
<script src='/javascripts/all.js'>
Because browsers tend to cache assets for a while, this means that users might not get your changes until their cac...
About Piwik
Piwik is the leading open-source analytics platform.
As such, it is an alternative to Google Analytics. Since it is open-source, it can be self-hosted and thus offers better data protection and privacy.
Notes
Actuality
Piwik does not show live reports, but updates its reports from time to time. piwik.pro seems to generate reports only once an hour. The exception to this is the dashboard, where you have a "Visitors in Real-time" widget that will show live tracking actions.
Date
Piwik analytics is always for a specific da...
The Current State of Telephone Links | CSS-Tricks
The linked article shows what current browsers do when you click a link like this:
<a href="tel:1-562-867-5309">1-562-867-5309</a>
Spoiler: The current state is sad
It's still the case that most desktop browsers can't do something useful with tel: links. They will usually open a dialog confirming that an external application will be opened. If the user confirms, she will see an error, or nothing at all.
On mobile browsers on the other hand, these links just open...
Represent astral Unicode characters in Javascript, HTML or Ruby
Here is a symbol of an eight note: ♪
Its two-byte hex representation is 0x266A.
This card describes how to create a string with this symbol in various languages.
All languages
Since our tool chain (editors, languages, databases, browsers) is UTF-8 aware (or at least doesn't mangle bytes), you can usually get away with just pasting the symbol verbatim:
note = '♪'
This is great for shapes that are easily recognized by your fellow programmers.
It's not...
Ubuntu MATE: Shortcut launcher for a web application
For some years Google Chrome has allowed you to add desktop icon for any web page by going to Tools / Add to desktop. Unfortunately this doesn't work reliably on Ubuntu MATE with recent Chromes: The icons could not be moved away from the desktop, or they would open the application as a new tab (instead of as a new window).
I found it to be easier to add a custom application launcher to the MATE panel.
In the Command field, enter this:
google-chrome --app="https://www.google.com/calendar"
This will open Google Calendar in a...
Google Chrome: How to find out your currently installed theme
So you downloaded a theme for Chrome a while ago and don't remember which one it is?
You can go to chrome://settings/appearance (on Chrome 61+) to see the theme's name, and click a link to open it in the Chrome Web Store.
If you are on an older version, or if the above no longer works, you have to check Chrome's Preferences file.
Linux
/home/YOUR_USER_NAME/.config/chromium/Default/Preferences
OSX
/Users/YOUR_USER_NAME/Library/Application Support/Google/Chrome/Default/Preferences
Windows
C:\Users\YOUR_US...
Name that Color
This service gives you a kind-of standard color name for any hex code.
This is useful if you want to extract some colors into a Sass $variable and are looking for a proper variable name.
About the HTML and the BODY tag
The <html> and <body> tags both come with some non-default behavior that you know from other tags.
Do not try to style html or body for positioning, width/heigth, or similar. Every browser has its own caveats and you can not test them all.
Generally speaking:
- Use the
htmltag to define your page's default background color (because on short pages or large screens, yourbodymay not be as tall as the browser window). - Use the
htmltag to define a basefont-sizeso you can use [remunits](https://www.sitepoint.com/underst...
Ubuntu MATE: Add a new panel
To add a new panel in MATE:
- Right-click on an existing panel and choose New Panel
- A new panel will appear at the bottom of the screen
- Right-click on the new panel, choose Properties and uncheck Expand
- Alt+Drag the panel to the desired location (e.g. to a second monitor)
- In the properties, check Expand again.
Using Google Analytics with Unpoly
The default Google Analytics might not work as expected with your Unpoly app. This is because your app only has a single page load when the user begins her session. After that only fragments are updated and the <script> tag that sends the page view to Google Analytics is probably never evaluated again.
Luckily you can fix this.
Simple mode: You just want to track all the page views
Embed your Google Analytics code as always.
Now add the following code snippet:...
There is no real performance difference between "def" and "define_method"
You can define methods using def or define_method. In the real world, there is no performance difference.
define_method is most often used in metaprogramming, like so:
define_method :"#{attribute_name}_for_realsies?" do
do_things
end
Methods defined via define_method are usually believed to have worse performance than those defined via def.
Hence, developers sometimes prefer using class_eval to define methods using def, like this:
class_eval "def #{attribute_name}_for_realsies?; do_things; end"
You can be...
ActiveRecord subselects - Today I Learned
Apparently you can pash a second scope to a hash-condition and the whole thing will be evaluated as a second SELECT statement with a subselect.
Note that sub-queries are extremely slow in MySQL, but they can make cases easier where performance does not matter so much (e.g. a migration on 50K records).
Images darken when getting converted with ImageMagick
When using ImageMagick to manipulate images, you might see that images get darker when beeing modified by newer versions of ImageMagick.
This usually happens with CMYK images beeing converted to RGB by IM.
Solution
At least in our version of ImageMagick (6.7.7) you can solve this by passing this parameter to ImageMagick -colorspace sRGB.
The RGB colorspace was okay for ImageMagick until version 6.6.9. RGB and sRGB switched obviously.
The Codeless Code
The Codeless Code is a charming series of stories about monks and nuns at a programming monastery.
Some stories to get started:
has_one association may silently drop associated record when it is invalid
This is quite an edge case, and appears like a bug in Rails (4.2.6) to me.
Update: This is now documented on Edgeguides Ruby on Rails:
If you set the :validate option to true, then associated objects will be validated whenever you save this object. By default, this is false: associated objects will not be validated when this object is saved.
Setup
# post.rb
class Post < ActiveRecord::Base
has_one :attachment
end
# attachm...
Ruby's default encodings can be unexpected
Note: This applies to plain Ruby scripts, Rails does not have this issue.
When you work with Ruby strings, those strings will get some default encoding, depending on how they are created. Most strings get the encoding Encoding.default_internal or UTF-8, if no encoding is set. This is the default and just fine.
However, some strings will instead get Encoding.default_external, notably
- the string inside a
StringIO.new - some strings created via
CSV - files read from disk
- strings read from an IRB
Encoding.default_external d...
Ruby 2.3 new features
Ruby 2.3.0 has been around since end of 2015. It brings some pretty nice new features! Make sure to read the linked post with its many examples!
Hash#fetch_values
Similar to Hash#fetch, but for multiple values. Raises KeyError when a key is missing.
attrs = User.last.attributes
attrs.fetch_values :name, :email
Hash#to_proc
Turns a Hash into a Proc that returns the corresponding value when called with a key. May be useful with enumerators like #map:
attrs.to_proc.call(:name)
attrs.keys.grep(/name/).map &attrs...
Download Ruby gems without installing
You can download .gem files using gem fetch:
gem fetch activesupport consul
This will produce files like active-support-5.0.0.gem and consul-0.12.1.gem in your working directory.
Dependencies will not be downloaded.
Ruby 2.3.0 has a safe navigation operator
As announced before, Ruby has introduced a safe navigation operator with version 2.3.0. receiver&.method prevents NoMethodErrors by intercepting method invocations on nil.
user = User.last
user&.name # => "Dominik"
# When there is no user, i.e. user is nil:
user&.name # => nil
This might remind you of andand, and indeed it behaves very similar. The only difference is in handling of `fa...
Linux: Find out which processes are swapped out
Processes in Linux might be put into Swap ("virtual memory") occasionally.
Even parts of a single process might be removed from memory and put into Swap.
In order to find out which processes remain within Swap, run this:
sudo grep VmSwap /proc/*/status | egrep -v "0 kB"
Keep in mind Swap is not evil by definition. Some bytes per process beeing put to Swap will not have that much of performance influence.
If you want the Linux virtual memory manager (which is responsible for the decision if and which processes are moved to Swap) to be...
virsh reload xml config file
If you have made any changes to a libvirt xml config file you have to reload is. One way is to reload the whole libvirtd service. But you can just reload corresponding domain xml too:
$ virsh define foo.xml