Is it possible, by using backports or something similar, to install and use gems that require a higher version of ruby than what is installed?
I am stuck on 1.8 and I am having troubles with the celluloid gem in relation with rspec. I thought that maybe backports would enable me to use it since most/all ruby 1.9.2+ features are then made available.
Forking celluloid on github and using backports to bring it down to 1.8 would be one possibility.
Although not a very simple one! :-)
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When authoring a gem, what would be reccomended practice for version restrictions of dependencies. For example I know that know that my gem works wih rubyzip version 2.x, but I also know that it works for 1.9 as well. Should I state
spec.add_runtime_dependency 'rubyzip', '>1.8'
or if the rubyzip version 1.9 is long time outdated, it is more common to "push" change for 2.x line? Also if I use the mentioned line, that I risk incompability with future versions, but on the other hand, leave the coice to the user.
Note: the questions is generall and dependency on rubyzip is just an example.
If you know that your gem works with rubyzip 1.9, then there's really no need to force people to use >=2.0 with it.
Sure, updating dependencies would be a good idea for your library-user to do, but it's not your job to be the "update-your-software-police"!
Specifying that the version must be < 3 is generally advisable (although not consistently done by developers), as there's a reasonable risk that a major dependency version bump will be incompatible with this version of your code.
So, as a compromise, you could do:
spec.add_runtime_dependency 'rubyzip', '>=1.9', '<3'
See the documentation for valid syntax examples.
I am using a quite recent version of ruby (2.5.1) but some old gems. I am having some issues. I was wondering, is it correct that some gems work only with certain versions of ruby?
If a gem worked with ruby 2.3.0, is it true that it will definitely work with 2.5.1 (i.e. because 2.5.1 > 2.3.0)? Or is that not always the case?
I guess what I'm asking is are newer ruby versions always backwards compatible with older gems?
If a gem worked with ruby 2.3.0, is it true that it will definitely
work with 2.5.1
This is not correct. Programming languages are evolving while growing. This means language maintainers are doing lots of improvements or refactorings that they are new features or removing old components from the language. When the language community announces for new features or removing old feature such as Fixnum in ruby, the developers should follow the instructions and refactor their codebase accordingly. In other words, developers should have a good test coverage to detect any fail and fix it instantly.
In your scenario, as well as I understand you do not have a test coverage. The only but the simple thing should do is just upgrade your gems' versions to latest.
Gem is simply a plug-in library written in Ruby.
Of course, Ruby is developing, new features are appearing, old ones are disappearing.
It's best practice to specify Ruby version in .gemspec file. For example, like this one.
But if not, then you have to manually check the performance. So you can read gem source code or try to use your gem and check it.
For automation, of course, it is best to use tests.
Starting at Ruby 2.1.0 the version policy has been that a change in the MINOR version may introduce API breaking changes.
Should any gem happen to use an API that changes, an incompatibility will arise.
The MINOR version number has changed twice between 2.3.* and 2.5.* so even if a gem happens to have been written in accordance with the documented API, there's no guarantee that it will continue to work unless the gem's maintainer takes the effort to test the gem (and upgrade it if necessary). Automated test suites help a lot.
A standard way to document version compatiblity that is actually tested against is by providing required_ruby_version in .gemspec files.
Interestingly, if a particular gem is really badly written, I imagine it might break even between compatible versions of Ruby. That's not something I've encountered in the Ruby ecosystem but I've made a similar mistake writing Java code (and Java is famous for its backward compatibility) where my own code accidentally used a class that wasn't part of the API. There are many gems. Who knows what's out there? :)
I'm using rvm on Ubuntu 12 to manage ruby versions/gemsets. I am testing various projects and some gems won't work with certain versions of Ruby or with each other. Is it possible to find which version of ruby an app was written for, so I can set my rvm to use that version and get the right gems when I run bundle install?
You can lookup the gems on rubygems.org. They are supposed to list what version of ruby they are compatible with, but that may not always be kept up to date.
If that doesn't narrow it down, you can check the gem's CHANGELOG file on github.
In the end, you may have to just try a few. There's only a handful of versions in common use, so it's not like you have to try then all.
in my experience ruby 1.9.3 is most widely supported at the time of this writing. Ruby 2.0 and 2.1 would also be good to try. 1.8.7 is pretty old and will likely give you a good bit of trouble, but it was the standard for a long time.
I'm a newbie, but I have a question regarding managing different versions of a gem, in my case, zurb-foundation. A new version just came out and I did a gem update and it made my older versions of the framework no longer compile.
My project contains a config.rb file that starts with
require 'zurb-foundation'
How does Ruby know to use the latest version of this? Is there a symlink somewhere pointing to the latest version? If so, I was thinking I could just re-write this symlink depending on which project I'm currently working in.
If you have multiple projects that use different versions of a gem you probably want to have a look at Bundler.
http://gembundler.com/
Bundler makes managing Ruby gems a breeze. This is highly recommended!
You should use RVM to manage multiple versions of ruby and gems.
Visit followings links to have an idea of rvm and to install.
https://rvm.io/
https://rvm.io/rvm/install/
What is the best way to make code using ftools also compatible with 1.9?
Use FileUtils. The APIs aren't totally compatible, but they're close, and FileUtils is also available for pre 1.9.
I'd update all code using ftools to use FileUtils, then iron out any discrepancies. It'll be worth it, FileUtils is here to stay.