Introducing Gem. Part one

Good day!

Introduction

Every hacker, and indeed a programmer, sooner or later begins to think about writing their libraries. He begins to get bored of dragging the same pieces of code into other projects. In Ruby, gem 's are the cure for this disease . So let's get to know him better.

Where to begin

To start, it would be nice to find a dusty file with the extension .rb . Have you found? Ok, move on.
Next, we need to create a file called hello-world.gemspec , where, as you probably guessed, hello-world is the name of your future gem.
Our next step will be to fill out this file itself (so to speak, a specification file). Its content should look like this:

Gem:Specification.new do |g|
     g.name = 'hello-world' # имя нашего gem'a
     g.version = '1.0' # его текущая версия
     g.summary = 'This is the first gem in my life.' # описание... сами знаете чего
     g.files = ['lib'/helloworld.rb'] # список файлов
     g.author = 'krovatti' # и, разумеется, автор... как же без него...
end

Great, but so far we have nothing to collect! Why? We forgot to create helloworld.rb . Let's fix our mistake immediately:

class HelloWorld
     def initialize
          puts "Hello, World!'
     end
end

Fuuuuh! Now that we have a minimal set of files, we can begin to build our gem with you. To build it, we must use the command

gem build hello-world.gemspec

If this operation is successful, the output will be a file called hello-world-1.0.gem . That's it, our gem is assembled.

Wait a minute

Do you want to share your gem with other people? If so, then you can easily do this with the following command:

gem push hello-world-1.0.gem

After executing this command, we should see the following:

Pushing gem to RubyGems.org ...
Successfully registered gem: hello-world (1.0)

Alas, we will not see this. Do you know why? Because you and I are not yet registered with RubyGems. You can do it here .
Now repeat the push command and everything will be ok.

All over the world

Now our gem will be able to install any rubist (at least from Australia) by running the command

gem install hello-world

After the installation is completed, we will write the following code and execute it:

require 'rubygems'
require 'hello-world'
inst = HelloWorld.new

As a result, we will see the cherished

Hello World!

in our console.

Stop it!

Actually, we inherited it on RubyGems. You have not forgotten about this? Delete our gem with the following command:

gem yank hello-world -v 1.0

Yes, and from our list of gems you can delete. Play and stop!

gem uninstall hello-world -v 1.0

Conclusion

That’s the end of the tale, and whoever listened is well done.
Today we met a truly wonderful tool called gem . Now you know that if something happens, gem will definitely come to your aid. And Chip, Chip, Chip ... And Dale hurries to us ...