Rich Codes

The Rubygems' web command

August 21, 2019 | 3 minute read

Wow! GSoC is almost on the final evaluation period! Time really flied! I think it’s a good moment to talk a bit about my work.

As I mentioned in this post, I’m working with Rubygems for GSoC 2019. My Pull Request is still open, but I think it’s stable enough to write about it (and the process of opening it).

I’ve added a new command to Rubygems: the web command. Its goal is to help developers to quickly find documentation about a particular gem.

How does it look?

It’s really simple to use this command. Take a look:

  • Do you wanna know what is the homepage for some gem? Just type gem web gem_name and it will output the URL.
  • Quickly access to the rubygems page? gem web -r gem_name brings it.
  • Can’t remember what that method does? gem web -d gem_name will get the documentation URL for you.
  • Want to dive into that good old messy code? Type gem web -c gem_name to get its source code.
  • I know, we’re too lazy to copy/paste the link: Just set the environment variable BROWSER (e.g. export BROWSER=google-chrome) and it will automatically open the URL in the browser for you. (Pay André Arko a beer for this suggestion 😜)

Some options, like rubytoolbox, were dropped because they make this feature to bound to 3rd party services

What’s happening under the hood?

Adding a new method for Rubygems is not rocket science (I have a post on how to do it). I’ll explain here a bit of how the web command works (I will be short on some sections to keep this clearer).

The first thing this commands does when it’s called is to run the method open_page(gem, options) from Gem::Web::Executor.

The method will try to find locally a gemspec of the gem you’ve typed with:

spec = Gem::Specification.find_by_name(gem)

The gemspec is important because it has all the info we need (homepage, documentation URI etc).

This was one of the differences between the original implementation of gem-web and mine. It was also a suggestion from the community, for security reasons.

If the gem is not installed, a Gem::MissingSpecError will be raised. In this case we have to search on the Rubygems API to find the gemspec.

The method fetch_remote_spec(gem) is responsible to fetch a remote gemspec (if the gem exists):

def fetch_remote_spec(gem)
  dep = Gem::Dependency.new(gem)
  found, _ = Gem::SpecFetcher.fetcher.spec_for_dependency(dep) # Here's the request
  ...
end

If everything went well, we should have the gem specification now (otherwise it will output an error message). Now the command see what options the user selected (homepage, rubygems page, source code or documentation) and calls open_browser(uri).

I think the implementation of this method is really simple, take a look:

def open_browser(uri)
  browser = ENV["BROWSER"]
  if browser.nil? || browser.empty?
    puts uri
  else
    system(browser, uri)
  end
end

If the BROWSER environment variable is set, the command uses it to open your browser with the link. Else, it juts prints the URI. Pretty easy, right?

The End

Well, that’s it! I told you that it wasn’t hard at all. This was one of the last posts I’ll do about my work on GSoC, since it’s getting to the end. In the next update I’ll talk about the lessons I’ve learned while contributing for Rubygems. ‘Till next time, folks!

Categories

cli gsoc ruby rubygems