Pros of Ruby

• Native performance for CPU-intensive tasks
• Smaller memory footprint
• Faster startup time

Cons of Ruby

• Limited platform support (primarily Unix-based systems)
• Lack of true multithreading due to Global Interpreter Lock (GIL)
• More challenging integration with Java libraries

Code Comparison

Ruby:

# Native C extension example
require 'fiddle'

libc = Fiddle.dlopen('/lib/libc.so.6')
puts libc['puts'].call('Hello from C!')

JRuby:

# Java interop example
require 'java'

java_import 'java.util.ArrayList'
list = ArrayList.new
list.add("Hello from Java!")
puts list.get(0)

The Ruby example demonstrates native C extension usage, which is not directly possible in JRuby. The JRuby example showcases seamless Java interoperability, a key feature not available in standard Ruby.

Both Ruby and JRuby have their strengths and use cases. Ruby excels in native performance and memory efficiency, while JRuby offers broader platform support and Java ecosystem integration. The choice between them depends on specific project requirements and constraints.

Pros of RubyGems

• Focused specifically on package management for Ruby
• Lighter weight and more streamlined for gem-related tasks
• Faster installation and updates for Ruby gems

Cons of RubyGems

• Limited to Ruby ecosystem, unlike JRuby's Java integration
• Lacks the full Ruby implementation that JRuby provides
• May have fewer contributors due to its more specialized focus

Code Comparison

RubyGems (gem installation):

gem install rails

JRuby (running Ruby code on JVM):

jruby -e "puts 'Hello from JRuby!'"

Key Differences

• Purpose: RubyGems focuses on package management, while JRuby is a full Ruby implementation on the JVM
• Language: RubyGems is written in Ruby, JRuby is implemented in Java
• Scope: RubyGems is specific to Ruby gems, JRuby provides Ruby compatibility for Java environments
• Performance: JRuby can offer better performance for certain tasks due to JVM optimizations
• Ecosystem: JRuby allows access to Java libraries, RubyGems is limited to Ruby gems

Use Cases

• Choose RubyGems for managing Ruby packages in standard Ruby projects
• Opt for JRuby when integrating Ruby with Java or leveraging JVM performance benefits

Pros of Rails

• Faster development speed and higher productivity due to convention over configuration
• Larger community and ecosystem with more gems and resources available
• Better suited for rapid prototyping and building full-stack web applications

Cons of Rails

• Generally slower runtime performance compared to JRuby
• Limited compatibility with Java libraries and frameworks
• Steeper learning curve for developers new to Ruby or web development

Code Comparison

Rails (config/routes.rb):

Rails.application.routes.draw do
  resources :users
  root 'home#index'
end

JRuby (example.rb):

require 'java'

java_import 'java.util.ArrayList'

list = ArrayList.new
list.add("Hello")
list.add("from")
list.add("JRuby")

The Rails code snippet demonstrates the simplicity of defining routes in a Rails application, while the JRuby example showcases its ability to seamlessly integrate with Java libraries and classes.

Pros of rbenv

• Lightweight and focused solely on Ruby version management
• Allows per-project Ruby versions without modifying the global environment
• Seamless integration with shell environments

Cons of rbenv

• Limited to managing Ruby versions only, not a full Ruby implementation
• Requires manual installation of Ruby versions
• May require additional plugins for certain functionalities

Code Comparison

rbenv:

# Install a Ruby version
rbenv install 3.0.0

# Set local Ruby version
rbenv local 3.0.0

# Check current Ruby version
rbenv version

JRuby:

# Example of Java interop in JRuby
require 'java'

java_import 'java.util.ArrayList'
list = ArrayList.new

puts list.class  # Java::JavaUtil::ArrayList

Key Differences

• rbenv is a version manager for Ruby, while JRuby is a Ruby implementation on the Java Virtual Machine (JVM)
• rbenv focuses on managing multiple Ruby versions, whereas JRuby provides Java interoperability
• rbenv is written in shell script, making it lightweight, while JRuby is a more complex system integrating Ruby with Java

Use Cases

• Choose rbenv for managing multiple Ruby versions in development environments
• Opt for JRuby when you need to integrate Ruby with Java or leverage JVM performance benefits

Pros of RVM

• Manages multiple Ruby versions and gemsets on a single system
• Provides easy switching between Ruby environments
• Supports installation of various Ruby implementations (including JRuby)

Cons of RVM

• Limited to Ruby ecosystem management
• Can be complex for beginners to set up and use
• Potential conflicts with system-wide Ruby installations

Code Comparison

RVM (installation):

\curl -sSL https://get.rvm.io | bash -s stable
source ~/.rvm/scripts/rvm
rvm install 2.7.2

JRuby (usage):

require 'java'
java_import 'java.util.ArrayList'
list = ArrayList.new
list.add("Hello from JRuby!")
puts list.get(0)

Key Differences

• Purpose: RVM is a version manager for Ruby, while JRuby is a Ruby implementation on the Java Virtual Machine
• Scope: RVM focuses on managing Ruby environments, JRuby enables Ruby-Java interoperability
• Usage: RVM is used for development environment setup, JRuby is used for running Ruby code on JVM
• Target audience: RVM targets Ruby developers, JRuby targets developers working with both Ruby and Java ecosystems

Both projects serve different purposes in the Ruby ecosystem, with RVM facilitating Ruby version management and JRuby enabling Ruby execution on the Java platform.

Pros of mruby

• Lightweight and embeddable, ideal for resource-constrained environments
• Designed for easy integration into existing C programs
• Highly customizable, allowing users to include only necessary features

Cons of mruby

• Limited standard library compared to JRuby
• Fewer third-party gems and libraries available
• May have compatibility issues with some Ruby code due to differences in implementation

Code Comparison

mruby:

#include <mruby.h>
#include <mruby/compile.h>

int main(int argc, char *argv[]) {
  mrb_state *mrb = mrb_open();
  mrb_load_string(mrb, "puts 'Hello, World!'");
  mrb_close(mrb);
  return 0;
}

JRuby:

import org.jruby.Ruby;
import org.jruby.RubyRuntimeAdapter;
import org.jruby.javasupport.JavaEmbedUtils;

public class JRubyExample {
    public static void main(String[] args) {
        Ruby runtime = JavaEmbedUtils.initialize(new String[0]);
        RubyRuntimeAdapter evaler = JavaEmbedUtils.newRuntimeAdapter();
        evaler.eval(runtime, "puts 'Hello, World!'");
    }
}

The code examples demonstrate the embedding process for each implementation. mruby is embedded in C, while JRuby is embedded in Java. mruby's approach is more lightweight and C-friendly, while JRuby offers deeper Java integration and a more complete Ruby environment.