Barby is a great Ruby gem to generate barcodes of all different sorts.
It includes support for QR codes via rQRCode; if you need to render only QR codes, you may want to use that directly.
Generating a barcode is simple:
>> Barby::Code128.new('Hello Universe').to_png
=> "\x89PNG\r\n\u001A..."
Barby supports several barcode types and you must require all necessary files explicitly.
For the example a...
Looks like ActiveState is trying to market a new Ruby distribution for Enterprises:
ActiveRuby Enterprise Edition is designed for businesses with large Ruby deployments in essential, mission-critical applications that, when down, could cost your business in lost revenue and a damaged reputation. Deploy Ruby with confidence knowing you're using the most secure, enterprise-grade builds for the platforms that power your business. You'll get priority access to our Ruby experts for technical support and best prac...
There are various ways to run external commands from within Ruby, but the most powerful ones are Open3.capture3 and Open3.popen3. Since those can do almost everything you would possibly need in a clean way, I prefer to simply always use them.
Behind the scenes, Open3 actually just uses Ruby's spawn command, but gives you a much better API.
Basic usage is
require 'open3'
stdout_str, error_str, status = Open3.capture3('/some/binary', 'with', 'some', 'args')
if status.success?...
A collection of code snippets which return a boolean value for a regex comparison.
regexp.match?(string) # Recommended for Ruby >= 2.4
!!(string =~ regexp) # Recommended for older Rubies
regexp === string
!(regexp !~ string)
The Ruby 2.4 method Regexp#match? does not set globals like $~ or $1, so it should be more performant.
Adding a gem means you take over the liability towards the external code.
Based on "To gem, or not to gem":
We have projects that have been developed using many different versions of Ruby. Since we do not want to constantly update every old project, we need to have many Ruby versions installed on our development machines.
Rbenv does that for us.
Rbenv installs ruby version and ruby gems to ~/.rbenv/versions/VERSION_NUMBER/.... This way many different Rubies can be installed at once.
When you run ruby or gem or bundler or any other Ruby binary
On application servers, gems are usually bundled into the project directory, at a location shared across deployments.
This is usually shared/bundle inside your project's root directory, e.g. /var/www/your-project/shared/bundle/.
If you can't find that, take a look at current/.bundle/config and look for BUNDLE_PATH.
When you are changing the version of RubyGems or Bundler on a system where gems are installed this way, you must wipe that bundle directory in addition to the user and system gems or gems that are already ins...
deadlock 0x7f8a4160a360: sleep:- (main) - /home/me/.rbenv/versions/1.8.7-p375/lib/ruby/gems/1.8/gems/bundler-1.14.3/lib/bundler/worker.rb:43
deadlock 0x7f8a38c03b08: sleep:- - /home/me/.rbenv/versions/1.8.7-p375/lib/ruby/gems/1.8/gems/bundler-1.14.3/lib/bundler/worker.rb:56
*** longjmp causes uninitialized stack frame ***: /home/me/.rbenv/versions/1.8.7-p375/bin/ruby terminated
... followed by a backtrace, memory map and more.
The culprit seems to be Bundler 1.14 when used with Ruby 1.8.7. [Downgrade to the maximu...
There are some inconvenient Gem dependencies. Resolve them by adding/modifying these lines in your Gemfile:
gem 'guard-livereload', '>= 2.5.2', require: false # Fixes a security issue
gem 'listen', '< 3.1' # 3.1 requires Ruby 2.2.5
It is not possible to install guard-livereload 2.5.2 on Ruby 1.8.7 because it depends on guard 2.8, which requires Ruby 1.9.
TruffleRuby is an experimental Ruby implementation that tries to achieve ~10x performance over MRI.
This has been on our radar for a while. They seem to have made significant progress running Rails, reducing start-up time and becoming runtime-independent of the JVM.
Also see [Running Optcarrot, a Ruby NES emulator, at 150 fps with the GUI!](https://eregon.me/blog/2016/11/28/optcarrot.htm...
Sometimes huge refactorings or refactoring of core concepts of your application are necessary for being able to meet new requirements or to keep your application maintainable on the long run. Here are some thoughts about how to approach such challenges.
Try to break your refactoring down in different parts. Try to make tests green for each part of your refactoring as soon as possible and only move to the next big part if your tests are fixed. It's not a good idea to work for weeks or months and wait for all puzzle pieces ...
You may know the double asterisk operator from Ruby snippets like Dir['spec/**/*_spec.rb'] where it expands to an arbitrary number of directories.
However, it is disabled by default on most systems. Here is how to enable it.
If you check your globstar shell option, it is probably disabled:
$ shopt globstar
globstar off
In that case, ** behaves just like * and will match exactly 1 directory level.
$ ls spec/**/*_spec.rb
spec/models/user_spec.rb
To enable it, run
shopt -s globstar
The double ast...
Ruby's regular expressions can be represented differently.
When serializing them, you probably want to use inspect instead of to_s.
For the examples below, consider the following Regexp object.
regexp = /^f(o+)!/mi
Using to_s will use a format that is correct but often hard to read.
>> regexp.to_s
=> "(?mi-x:^f(o+)!)"
As the Ruby docs say:
...
So you're getting an error like this:
undefined method `activate_bin_path' for Gem:Module (NoMethodError)
Here is what happened:
bundle, rake or rails) with code that only works with modern Rubygems versionsGem.activate_pin_path(...) that was written out by th...TL;DR: Update the 'net-ssh' gem by adding to your Gemfile:
gem 'net-ssh', '=2.9.1'
Now run bundle update net-ssh. It has no dependencies so it shouldn't update other gems.
If you're using Ruby 1.8.7 and want to update net-ssh to a version > 2.9.1 you also need to add this to your gemfile:
gem 'backports', :require => false
... and in your deploy.rb add this:
require 'backports/1.9.2/array/select'
You propably have an older version of Capistrano and thereby an older version of `n...
So you're getting this failure when running bundle install on an older project:
Your Gemfile.lock is corrupt. The following gems are missing from the DEPENDENCIES section: 'archive-tar-minitar' 'hoe' 'rcov'
This happens when you are using a new version of Bundler with a project that was bundled with a very old version of Bundler. For reasons unknown, the Bundler dependency API returns different dependencies for some gems (like ruby-debug or rainpress) than the dependencies found in the downloaded gemspecs. While old versi...
This card tries to summarize by example the different uses of heredoc.
<< vs. <<- vs. <<~
strip_heredoc vs. squish
strip_heredoc should be used for a text, where you want to preserve newlines. (multi-line -> multi-line)
squish should be used for a text, where you want to squish newlines. (multi-line -> one-line)
def foo
bar = <<~TEXT
line1
line2
line3
TEXT
puts bar.inspect
end
foo => "line1\nline2\nline3\n"
Read more: [Unindent HEREDOCs in Ruby 2.3](/m...
You can use three different versions of the regular expression syntax in grep:
-G
-E(POSIX)-P (PCRE)Difference between basic and extended:
In basic regular expressions the meta-characters '?', '+', '{', '|', '(', and ')' loose their special meaning; instead use the backslashed versions '?', '+', '{', '|', '(', and ')'.
Difference between extended (POSIX) and perl (PCRE): E.g. \d is not supported in POSIX.
This g...
When you're writing specs for ActiveRecord models that use memoization, a simple #reload will not do:
it 'updates on changes' do
subject.seat_counts = [5]
subject.seat_total.should == 5
# seat_total is either memoized itself, or using some
# private memoized method
subject.seat_counts = [5, 1]
subject.seat_total.reload.should == 6 # => Still 5
end
You might be tempted to manually unmemoize any memoized internal method to get #seat_total to update, but that has two disadvant...
Yesterday I stumbled across a talk in which the guy mentioned module sub-classing. I was curious what you can do with it and found his blog post with a cool example. It allows you to inject some state into the module you are including elsewhere. Check it out!
class AttributeAccessor < Module
def initialize(name)
@name = name
end
def included(model)
super
define_accessors
end
private
def define_accessors
ivar = "@#{@name}"
define_writer(ivar)
define_reader(ivar)
end
def define_writer(ivar)
...
In order to have monitoring for Sidekiq (like queue sizes, last run of Sidekiq) your application should have a monitoring route which returns a json looking like this:
{
"sidekiq": {
"totals": {
"failed": 343938,
"processed": 117649167
},
"recent_history": {
"failed": {
"2016-11-06": 1,
"2016-11-07": 46,
"2016-11-08": 0,
"2016-11-09": 0,
"2016-11-10": 0
},
"processed": {
"2016-11-06": 230653,
"2016-11-07": 230701,
"2016-11-08"...
A gem is activated if it is either in the current bundle (Gemfile.lock), or if you have manually activated it using Kernel#gem (old-school).
To detect if e.g. activerecord has been activated:
if Gem.loaded_specs.has_key?('activerecord')
# ActiveRecord was activated
end
To detect if e.g. activerecord ma...