This is a document containing the most important things about ruby, and tends to be a learning path to Ruby as to become a proficient developer in this language.

The guide will be divided in three components aimed to be followed in order:

1. A gentle introduction to the Ruby sintax and singularities.

   • To get a quick overview on the Ruby language and sintax, Ruby in 20 minutes needs to be your first option.

   • For differences between Ruby and other languages, Ruby unique traits & Ruby for other languages may be handy, and also presents comparisons between Ruby and C and C++, Java, Perl, PHP and Python.

   • To be more alligned on Ruby best practices, you can refer to : Ruby style guide

2. A theorical and practical primer on the main concepts of Ruby.

   • Learn Ruby The Hard Way Disclaimer: there are lessons that I didn't find so useful, but if you feel the need to check them out, you can find them in The 'Learn Ruby The Hard Way' website

   • String Formatting

   • Prompting to the user

   • Program Arguments

   • Reading files

   • File manipulation

   • Working with modules

   • Conditionals

   • Arrays and Loops

   • Symbols (Idiomatic cheatsheet)

   • Hashmaps

   • Modules, Classes and Objects

   • Object-Oriented Ruby For more OOP exercises, you can also use Excercise 42, Execise 43 and Exercise 44

   • Project Structure

   • Writing tests

     • Programming Ruby Programming Ruby is a documentation site with a lot of helpful information on Ruby. I will only add the links that add something of value which we didn't found on Ruby the Hard Way, or the ones that are not covered in that book.
       • Expressions
       • Handling Exceptions
       • Threads
       • Reflection Reflection is the ability to look under the hood on a class or object in order to understand for example, which methods can be called.
       • Modules Including files & mixins.

3. Useful Libraries

   • Ethereum/related libraries:
     • Ethereum Ruby library and this helpful tutorial
     • Web3 RPC client for Ethereum node
     • Another Web3 RPC client for Ethereum node
     • A simple Ethereum library for Ruby

4. Notes on the different issues I have come across.

   • Installing a gem RubyGems is the package manager of Ruby, which can be helpful for you in the development process. For example, in my case I wanted to install SQLITE3 to be able to easily interact with a SQLite database. To install a gem, the command used is: gem install <gemName> But, running that command was ending with an error:

         ERROR: Failed to build gem native extension.
             current directory: /var/lib/gems/2.5.0/gems/nokogiri-1.10.3/ext/nokogiri
             /usr/bin/ruby2.5 -r ./siteconf20190807-22036-snjnej.rb extconf.rb mkmf.rb can't find header files for ruby at /usr/lib/ruby/include/ruby.h
             extconf failed, exit code 1
     
             Gem files will remain installed in /var/lib/gems/2.5.0/gems/n-okogiri-1.10.3 for inspection.
             Results logged to /var/lib/gems/2.5.0/extensions/x86_64-linux/2.5.0/nokogiri-1.10.3/gem_make.out
     

     Which seems to be a problem on the header files, but after Googling for a bit, I found the command needed to install the ruby-dev dependencies that are needed to fix this problem in an Ubuntu box:

     sudo apt-get install rubyruby -e 'puts RUBY_VERSION[/\d+.\d+/]'-dev

     Also, at this point I added the Ruby package path to source by running:

     gem env and grabbing the "RUBY E XECUTABLE" value, and then:

     export PATH=$PATH:/var/lib/gems/2.5.0/

     Nevertheless, once I ran again the command, I encountered another error:

         Fetching: sqlite3-1.4.1.gem (100%)
             Building native extensions. This could take a while...
             ERROR:  Error installing sqlite3:
                     ERROR: Failed to build gem native extension.
     
                 current directory: /var/lib/gems/2.5.0/gems/sqlite3-1.4.1/ext/sqlite3
             /usr/bin/ruby2.5 -r ./siteconf20190807-9493-wzuepa.rb extconf.rb
             checking for sqlite3.h... no
             sqlite3.h is missing. Try 'brew install sqlite3',
             'yum install sqlite-devel' or 'apt-get install libsqlite3-dev'
             and check your shared library search path (the
             location where your sqlite3 shared library is located).
             *** extconf.rb failed ***
             Could not create Makefile due to some reason, probably lack of necessary
             libraries and/or headers.  Check the mkmf.log file for more details.  You may
             need configuration options.
     
             Provided configuration options:
                     --with-opt-dir
                     --without-opt-dir
                     --with-opt-include
                     --without-opt-include=${opt-dir}/include
                     --with-opt-lib
                     --without-opt-lib=${opt-dir}/lib
                     --with-make-prog
                     --without-make-prog
                     --srcdir=.
                     --curdir
                     --ruby=/usr/bin/$(RUBY_BASE_NAME)2.5
                     --with-sqlcipher
                     --without-sqlcipher
                     --with-sqlite3-config
                     --without-sqlite3-config
                     --with-pkg-config
                     --without-pkg-config
                     --with-sqlcipher
                     --without-sqlcipher
                     --with-sqlite3-dir
                     --without-sqlite3-dir
                     --with-sqlite3-include
                     --without-sqlite3-include=${sqlite3-dir}/include
                     --with-sqlite3-lib
                     --without-sqlite3-lib=${sqlite3-dir}/lib
     
             To see why this extension failed to compile, please check the mkmf.log which can be found here:
     
             /var/lib/gems/2.5.0/extensions/x86_64-linux/2.5.0/sqlite3-1.4.1/mkmf.log
     
             extconf failed, exit code 1
     
             Gem files will remain installed in /var/lib/gems/2.5.0/gems/sqlite3-1.4.1 for inspection.
             Results logged to /var/lib/gems/2.5.0/extensions/x86_64-linux/2.5.0/sqlite3-1.4.1/gem_make.out
         ```
         
     

   This error was because of missing dependencies (again), and the command to add them is: sudo apt-get install libsqlite3-dev

   Now, you can run gem install sqlite3 and everything will work correctly So, you can take two takeaways from this Note:

   • Add your Gem folder to PATH.
   • You may be missing some dependencies to install the correct Gem, so search for the error in DuckDuckGo and enjoy the slick StackoverFlow widget they have on their search engine.