For a project I'm working on, I have to do some work on an existing Ruby Gem. I haven't got much previous experience with Ruby and am struggling with a few aspects.
I have the repository cloned locally. I need to edit the current files in the /lib/ directory, which I can do. Is it possible for me to compile the edited files into a Gem and run this Gem? Any help would be really appreciated.
Yes! You can include the gem in a local project and point the Gemfile to your local directory:
Gemfile
source 'https://rubygems.org'
gem 'my_local_gem', path: '/absolute/path/to/your/gem'
Then edit the gem, run your local program and see the changes.
Additionally, you don't always have to clone a whole gem, you can install it via rubygems and use bundle open <gem_name> to open the gem's contents in your supplied editor.
I have written a post describing just that and more here.
Related
How do I configure bundler so that when I run bundle install it looks for gems under /my/custom/path first and if it doesn't find there then try to fetch them from a ruby gem remote repository hosted under https://a.nice.host and downloads those into ./local/relative/path (relative to cwd for example). I would like to avoid the bundler looking at default gem installation system path or rubygems.org
The syntax for sourcing a gem from a local folder is:
gem 'some-gem-name', path: '/my/custom/path'
And the syntax for specifying a custom source is:
gem 'another-gem-name', source: 'https://a.nice.host'
And to install gems into a specific local folder, you can run:
bundle install --path ./local/relative/path
Now, that's probably all the tools you need, in truth... (And in fact, especially for that last requirement, you may instead wish to look into rvm gemsets, or using bundle install --deployment.)
But you did also ask about "looking in a local folder first, and only falling back to a remote source if it doesn't exist". That's quite an odd requirement (usually you'd only want to explicitly opt-in to fetching gems from a local path?!), but to answer this question as you've asked it...
A Gemfile is literally just ruby code! So you can define this logic using... You guessed it, ruby! For example:
if File.exists?('/my/custom/path')
gem 'some-gem-name', path: '/my/custom/path'
else
gem 'some-gem-name', source: 'https://a.nice.host'
end
If this (unusual) pattern needs to be repeated in multiple places, you could wrap it into some helper method.
For more information on the configuration options of bundler, please see the documentation.
I am trying to contribute to a Ruby gem and I don't understand how to test a local gem without using a globally installed gem.
The gem I want to contribute to is a command line interface gem. I clone the gem into a directory then cd into that directory. However, when I run commands in the terminal when I'm in the cloned project directory it still uses the global gem. I've even run
gem uninstall gemname
then while inside the newly cloned gem directory I redo
gem install gemname.
No matter what changes I make to the gem, I can't see the results or what my contributions are doing because it's always running the global gem.
When I do try to type a command line command that is supposed to interact with the gem while in the cloned gem directory I get:
-bash: ~/.gem/ruby/2.1.0/bin/githubrepo: No such file or directory
I've done a ton of research but I'm just not getting it. Help?
gem install gemname will look for a .gem file in the current directory. If not found it will look for it on the web.
gem install --local /path/to/your/gemname.gem will allow you to target a particular directory. You may need to gem build gemname.gemspec first, so it has your changes.
Instead of doing this, I would write tests in the gem directory itself. It's likely that when running code in there, you can simply require 'gemname' in Ruby to get the gem functionality.
If it's a well-written gem, it should have tests already. They will most likely be in a directory called test or spec. Have a look at these tests and try to carry on in that style to test your changes. This will make your code changes far far more likely to be accepted as a pull request.
I am trying to install eventmachine Gem, however a line needs to be commented out in the source for this to work on Ruby 2.0 on Windows x64.
I have tried modifying the Gem source in the Ruby build folder but each time I run gem install eventmachine it overwrites my changes. From the command line help there does not appear to be a way to rebuild the gem without unpacking fresh source, however there may be a workaround.
Is there a way to build my slightly tweaked source for this Gem?
Don't install the gem like that. Instead, build your own version and install that instead by specifying the path to the .gem file that is produced as part of the build process.
I've found the easiest way to get this right is to create a fork, set the fork's git path in your Gemfile, and bundle install which will take care of compiling things and installing them correctly.
Ok figured it out thanks to help from #tadman.
Ended up just installing locally from source rather than tweaking the official source downloaded by gem and preventing it from being overwritten. These are the exact steps ...
Clone locally from Github (or wherever)
Make your changes to the source
If there is a .gemspec file in the root directory
Open terminal in the directory and enter gem build GEMNAME.gemspec
Finally enter gem install GEMNAME-VERSION.gem
If there is not .gemspec but there is a file called "gem" or "build" or something similar , then you may have to build using rake according to this reply
I started developing ruby lately and I really like it, But I feel somehow lost. I developed a script that does "whatever" and that scripts requires many gems like nokogiri and colorize. I now want to deploy the script, so after reading a while I found many people saying that deploying as a gem is the best approach. So my question is simple? Is there any tool that I can use to create a gem of my script file and include all the gem dependencies(nokogiri) in the new gem?
I am using ubuntu!
Thanks alot
Building a gem consists of basically creating a simple directory structure for your script, and a special file known as a gemspec that will list all its dependencies. That gemspec can be used with rubygems to create a gem file (*.gem), which can be installed using rubygems or uploaded to rubygems.org for public consumption.
There are several tools that automate part of this process. A relatively simple one is the Bundler gem, which will both take care of dependencies during development, and make it easy for you to package your gem. This article contains enough information to get you started with gem development using bundler.
The best way to make a gem is to use the bundler program to build a skeleton:
# bundler gem (gem_name)
bundler gem geil_gem
This will create a template gemspec file and give you the basic structure needed for your gem to have a setup command, a console and be ready to build into a working gem (both found in the bin folder of your skeleton project). From here you can add a command binary or build out the gem as a library using the lib directory or start with tests by adding rspec to the gemspec and creating a test folder.
I am trying to install the mechanize gem that is supposed to work with 1.9 from here: http://github.com/kemiller/mechanize but I do not know how to add it manually.
I am using Windows, I could just copy the folder to the gems directory, but how do I initialize it?
I'm not sure I understand the problem. gem install mechanize doesn't work? It produces version 0.9.3 for me, which matches the gemspec of the library you linked to.
EDIT: you're on 1.9. I knew that. Disregard my hasty post, not familiar enough with Windows to offer any help on building the extensions.
I would use the bundler gem using the command gem install bundler. This will create a file called Gemfile in your project directory where you can put your dependencies for the specific project that you are working on. In the Gemfile, you will need to specify gem mechanize. If you want a specific version include ~> VERSION after. After, run the command bundle install. This will install the gem you want and use it in your project.