Table of Contents

1. Features
2. Installation
3. Usage
   1. Basic Example
   2. Advanced Usage
   3. Skipping Callbacks
4. Callback Options
5. How It Works
6. 📚 Use Cases
7. 🤝 Contributing
8. 📄 License

SolidCallback

SolidCallback adds powerful method interception capabilities to your Ruby classes with near-zero overhead. Clean, flexible, and unobtrusive.

Features

• 🔄 Method Lifecycle Hooks: before_call, after_call, and around_call - intercept methods without modifying their code
• 🧩 Zero-coupling: Keep your business logic and cross-cutting concerns separate
• 🔍 Selective targeting: Apply callbacks to specific methods or all methods
• ⚡ Performance-focused: Minimal overhead through efficient method wrapping
• 🔒 Thread-safe: Safely use in concurrent applications
• 📝 Conditional execution: Run callbacks only when specific conditions are met

Installation

Add this line to your application's Gemfile:

  gem 'solid_callback'

And then execute:

  bundle install

Or install it yourself:

  gem install solid_callback

Usage

Basic Example

require 'solid_callback'

class UserService
  include SolidCallback

  before_call :authenticate
  after_call :log_activity
  around_call :measure_performance

  def find_user(id)
    puts "Finding user with ID: #{id}"
    { id: id, name: "User #{id}" }
  end

  def update_user(id, attributes)
    puts "Updating user #{id} with #{attributes}"
    { id: id, updated: true }
  end

  private

  def authenticate
    puts "🔐 Authenticating request"
  end

  def log_activity
    puts "📝 Logging activity"
  end

  def measure_performance
    start_time = Time.now
    result = yield  # Execute the original method
    duration = Time.now - start_time
    puts "⏱️ Method took #{duration} seconds"
    result  # Return the original result
  end
end

service = UserService.new
service.find_user(42)

Advanced Usage

Apply callbacks to specific methods:

class PaymentProcessor
  include SolidCallback

  before_call :validate_amount, only: [:charge, :refund]
  after_call :send_receipt, only: [:charge]
  after_call :notify_fraud_department, only: [:flag_suspicious]
  around_call :transaction, only: [:charge, :refund]

  # Rest of class...
end

Use conditional callbacks:

class DocumentProcessor
  include SolidCallback

  attr_reader :document_size

  before_call :check_permissions
  before_call :backup_document, if: :large_document?
  around_call :with_retry, unless: :read_only?

  def process_document(doc)
    # Implementation...
  end

  private

  def large_document?
    @document_size > 10_000
  end

  def read_only?
    # Some condition
  end
end

You can even use procs for conditions:

before_call :notify_admin, if: -> { Rails.env.production? }

Skipping Callbacks

Skip callbacks for specific methods:

class ApiService
  include SolidCallback

  before_call :rate_limit

  skip_callbacks_for :health_check

  def get_data
    # Implementation...
  end

  def health_check
    # This method won't trigger the rate_limit callback
    { status: "ok" }
  end
end

Callback Options

Each callback method accepts the following options:

Option	Description
only	Array of method names to which the callback applies
except	Array of method names to which the callback does not apply
if	Symbol (method name) or Proc that must return true for the callback to run
unless	Symbol (method name) or Proc that must return false for the callback to run

How It Works

Callbacker uses Ruby's metaprogramming to wrap your methods with callback functionality:

1. When included, it extends your class with callback registration methods
2. When a callback is registered, it stores the configuration
3. When a method is defined, it wraps the method with callback handling code
4. When the method is called, it executes the callbacks in the proper order

📚 Use Cases

• Authentication & Authorization
• Logging & Monitoring
• Caching
• Performance measurement
• Error handling
• Background job retries
• Transaction management
• Input validation
• Data transformation

🤝 Contributing

Bug reports and pull requests are welcome on GitHub at https://github.com/gklsan/solid_callback/issues.

📄 License

The gem is available as open source under the terms of the MIT License.