Rulify 🧠

A lightweight, chainable, and prioritized rule engine for Python that makes business logic management simple and elegant.

🚀 Quick Start

pip install rulify

from rulify import Rule, RuleEngine

def is_hot(ctx): 
    return ctx["temp"] > 30

def turn_on_ac(ctx):
    ctx["ac"] = True
    print("AC turned ON")
    return ctx

# Create engine and add rules
engine = RuleEngine()
engine.add_rule(Rule("Hot Check", is_hot, turn_on_ac, priority=10))

# Run with context
context = {"temp": 35}
result = engine.run(context)
print(result)  # {'temp': 35, 'ac': True}

✨ Features

• 🎯 Rule Prioritization: Execute rules in order of importance
• 🔗 Rule Chaining: Chain rules together for complex workflows
• ⚡ Lightweight: Zero external dependencies
• 🐍 Pythonic: Clean, intuitive API design
• 🔧 Flexible: Works with any Python data structure

📖 Documentation

Basic Usage

from rulify import Rule, RuleEngine

# Define conditions and actions
def is_high_temp(ctx): 
    return ctx.get("temp", 0) > 30

def cool_down(ctx): 
    ctx["ac"] = True
    ctx["fan_speed"] = "high"
    print("Cooling system activated")
    return ctx

def is_low_temp(ctx): 
    return ctx.get("temp", 0) < 20

def heat_up(ctx): 
    ctx["heater"] = True
    print("Heating system activated")
    return ctx

# Create engine and add rules
engine = RuleEngine()
engine.add_rule(Rule("Too Hot", is_high_temp, cool_down, priority=10))
engine.add_rule(Rule("Too Cold", is_low_temp, heat_up, priority=5))

# Process context
context = {"temp": 33}
result = engine.run(context)

Rule Chaining

def check_weather(ctx):
    return ctx.get("weather") == "rainy"

def grab_umbrella(ctx):
    ctx["umbrella"] = True
    print("Grabbed umbrella")
    return ctx

def check_location(ctx):
    return ctx.get("location") == "outdoor"

def stay_inside(ctx):
    ctx["location"] = "indoor"
    print("Staying inside")
    return ctx

# Chain rules together
umbrella_rule = Rule("Grab Umbrella", check_weather, grab_umbrella)
location_rule = Rule("Stay Inside", check_location, stay_inside, next_rule=umbrella_rule)

engine = RuleEngine()
engine.add_rule(location_rule)

context = {"weather": "rainy", "location": "outdoor"}
result = engine.run(context)

Advanced Example: E-commerce Order Processing

def is_vip_customer(ctx):
    return ctx.get("customer_tier") == "VIP"

def apply_vip_discount(ctx):
    ctx["discount"] = 0.15
    ctx["priority_shipping"] = True
    print("VIP discount applied")
    return ctx

def is_high_value_order(ctx):
    return ctx.get("order_total", 0) > 1000

def apply_bulk_discount(ctx):
    ctx["discount"] = ctx.get("discount", 0) + 0.10
    print("Bulk discount applied")
    return ctx

def is_express_shipping(ctx):
    return ctx.get("shipping_type") == "express"

def calculate_shipping_cost(ctx):
    base_cost = 10
    if ctx.get("priority_shipping"):
        base_cost += 5
    ctx["shipping_cost"] = base_cost
    return ctx

# Build order processing engine
engine = RuleEngine()
engine.add_rule(Rule("VIP Customer", is_vip_customer, apply_vip_discount, priority=20))
engine.add_rule(Rule("High Value", is_high_value_order, apply_bulk_discount, priority=15))
engine.add_rule(Rule("Express Shipping", is_express_shipping, calculate_shipping_cost, priority=10))

# Process order
order = {
    "customer_tier": "VIP",
    "order_total": 1200,
    "shipping_type": "express"
}

result = engine.run(order)
print(result)

🛠️ API Reference

RuleEngine

The main engine for managing and executing rules.

Methods

• add_rule(rule): Add a rule to the engine
• run(context): Execute all rules against the given context

Rule

Represents a single rule with condition, action, and metadata.

Constructor

Rule(name, condition, action, priority=0, next_rule=None)

• name (str): Human-readable name for the rule
• condition (callable): Function that returns True/False based on context
• action (callable): Function to execute when condition is True
• priority (int): Higher numbers execute first (default: 0)
• next_rule (Rule): Optional rule to chain after this one

🤝 Contributing

Contributions are welcome! Please feel free to submit a Pull Request.

1. Fork the repository
2. Create your feature branch (git checkout -b feature/AmazingFeature)
3. Commit your changes (git commit -m 'Add some AmazingFeature')
4. Push to the branch (git push origin feature/AmazingFeature)
5. Open a Pull Request

📄 License

This project is licensed under the MIT License - see the LICENSE file for details.

🙏 Acknowledgments

• Inspired by business rule engines and workflow management systems
• Built with simplicity and performance in mind

Made with ❤️ by Ertuğrul Kara