smartswitch 0.9.2

Named function registry and plugin system for Python

SmartSwitch

Named function registry and plugin system for Python

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SmartSwitch is a lightweight Python library for managing function registries with named handlers and extensible plugin architecture. Perfect for API routers, command dispatchers, event handlers, and any scenario where you need clean, maintainable function organization.

What is SmartSwitch?

SmartSwitch provides two core capabilities:

1. Named Handler Registry: Register functions by name or custom alias, then call them dynamically
2. Plugin System: Extend functionality with middleware-style plugins for logging, validation, async support, etc.

When to use SmartSwitch:

• Building API routers or command dispatchers
• Creating plugin-based architectures
• Organizing related functions into callable registries
• Need middleware-style function wrapping
• Want clean, testable code instead of if-elif chains

Installation

pip install smartswitch

Quick Start

Basic Handler Registry

from smartswitch import Switcher

# Create a registry
ops = Switcher()

# Register handlers
@ops
def save_data(data):
    return f"Saved: {data}"

@ops
def load_data(data):
    return f"Loaded: {data}"

# Call by name
result = ops('save_data')("my_file.txt")
print(result)  # → "Saved: my_file.txt"

Custom Aliases

ops = Switcher()

# Register with custom names
@ops('reset')
def destroy_all_data():
    return "Everything destroyed"

@ops('clear')
def remove_cache():
    return "Cache cleared"

# Call with friendly alias
result = ops('reset')()
print(result)  # → "Everything destroyed"

Prefix-Based Auto-Naming

Use naming conventions to automatically derive handler names:

# Set a prefix for automatic name derivation
protocols = Switcher(prefix='protocol_')

@protocols  # Auto-registers as 's3_aws' (removes prefix)
def protocol_s3_aws():
    return {"type": "s3", "region": "us-east-1"}

@protocols  # Auto-registers as 'gcs'
def protocol_gcs():
    return {"type": "gcs", "bucket": "data"}

# Call by derived names
result = protocols('s3_aws')()
print(result)  # → {"type": "s3", "region": "us-east-1"}

Hierarchical Organization

Organize multiple Switchers into parent-child relationships:

from smartswitch import Switcher

class MyAPI:
    # Main switcher
    main = Switcher(name="main")

    # Child switchers with hierarchy
    users = Switcher(name="users", parent=main, prefix="user_")
    products = Switcher(name="products", parent=main, prefix="product_")

    @users
    def user_list(self):
        return ["alice", "bob"]

    @products
    def product_list(self):
        return ["laptop", "phone"]

# Direct access
api = MyAPI()
api.users('list')()  # → ["alice", "bob"]

# Hierarchical access via parent
api.main('users.list')()  # → ["alice", "bob"]
api.main('products.list')()  # → ["laptop", "phone"]

# Discover children
for child in api.main._children.values():
    print(f"{child.name}: {list(child._methods.keys())}")

Plugin System

Extend SmartSwitch functionality with plugins:

from smartswitch import Switcher

# Create switcher with logging plugin
sw = Switcher().plug('logging', mode='print,after,time')

@sw
def my_handler(x):
    return x * 2

# Use handler - logs output automatically
result = sw('my_handler')(5)  # → 10
# Output: ← my_handler() → 10 (0.0001s)

# Use before+after for debugging
sw_debug = Switcher().plug('logging', mode='print,before,after')

@sw_debug
def process(data):
    return f"Processed: {data}"

sw_debug('process')("test")
# Output:
# → process('test')
# ← process() → Processed: test

Creating Custom Plugins

from smartswitch import BasePlugin

class ValidationPlugin(BasePlugin):
    """Validate arguments before handler execution."""

    def wrap_handler(self, switch, entry, call_next):
        def wrapper(*args, **kwargs):
            # Custom validation logic
            if not args:
                raise ValueError("No arguments provided")
            return call_next(*args, **kwargs)
        return wrapper

# Use custom plugin
sw = Switcher().plug(ValidationPlugin())

@sw
def process(data):
    return f"Processed: {data}"

# Plugin validates before execution
result = sw('process')("test")  # → "Processed: test"

Chaining Multiple Plugins

from smartswitch import Switcher
from my_plugins import CachePlugin, MetricsPlugin

sw = (Switcher()
      .plug('logging', mode='print,after,time')
      .plug(CachePlugin(ttl=300))
      .plug(MetricsPlugin(namespace='api')))

@sw
def expensive_operation(x):
    # Plugins execute in order: logging → cache → metrics
    return x * 2

Real-World Examples

API Router

from smartswitch import Switcher

api = Switcher(name="api")

@api('list_users')
def get_users(page=1):
    # Fetch from database
    return {"users": [...], "page": page}

@api('create_user')
def create_user(data):
    # Create user
    return {"id": 123, "created": True}

@api('not_found')
def handle_404():
    return {"error": "Not Found", "status": 404}

# Route requests
def handle_request(endpoint, **kwargs):
    handler = api._methods.get(endpoint)
    if handler:
        return api(endpoint)(**kwargs)
    return api('not_found')()

Command Dispatcher

cli = Switcher(prefix='cmd_')

@cli
def cmd_backup(target):
    return f"Backing up {target}"

@cli
def cmd_restore(source):
    return f"Restoring from {source}"

@cli('help')
def cmd_show_help():
    return "Available commands: " + ", ".join(cli._methods.keys())

# Dispatch commands
command = input("Enter command: ")
result = cli(command.split()[0])(*command.split()[1:])

Event Handler

events = Switcher()

@events('user.created')
def on_user_created(user_id):
    print(f"Welcome email sent to user {user_id}")

@events('user.deleted')
def on_user_deleted(user_id):
    print(f"Cleanup completed for user {user_id}")

# Emit events
def emit(event_name, *args):
    if event_name in events._methods:
        events(event_name)(*args)

Key Features

Core Functionality

• Named handler registry: Register and call functions by name
• Custom aliases: Use friendly names different from function names
• Prefix-based naming: Convention-driven automatic name derivation
• Hierarchical organization: Parent-child Switcher relationships with dotted-path access
• Zero dependencies: Pure Python 3.10+ standard library
• Type-safe: Full type hints support

Plugin System

• Extensible architecture: Add custom functionality via plugins
• Clean API: Access plugins via sw.plugin_name.method() pattern
• Composable: Chain multiple plugins seamlessly
• Standard plugins: Built-in logging plugin included
• External plugins: Third-party packages can extend functionality

Developer Experience

• Modular & testable: Each handler is an independent, testable function
• Clean code: Replace if-elif chains with declarative registries
• High performance: Optimized with caching (~1-2μs overhead per call)
• Well documented: Comprehensive guides and tested examples

Performance

SmartSwitch adds minimal overhead (~1-2 microseconds per dispatch). For real-world functions doing actual work (API calls, database queries, business logic), this is negligible:

Function execution time: 50ms (API call)
SmartSwitch overhead: 0.002ms
Relative impact: 0.004% ✅

Good for:

• API handlers and request routers
• Command dispatchers
• Event handling systems
• Business logic organization
• Any function doing real work (>1ms execution time)

Consider alternatives for:

• Ultra-fast functions (<10μs) called millions of times per second
• Simple 2-3 case switches (plain if-elif is fine)

See Performance Best Practices for details.

Thread Safety

SmartSwitch is designed for typical Python usage patterns:

• Handler dispatch (calling sw('name')(args)) is fully thread-safe - uses read-only operations
• Decorator registration should be done at module import time (single-threaded)

Recommended usage:

# Module level - executed once at import (safe)
switch = Switcher()

@switch
def my_handler(x):
    return x * 2

# Runtime - called many times (thread-safe)
result = switch('my_handler')(42)

For advanced scenarios requiring runtime registration in multi-threaded applications, external synchronization is needed.

Documentation

📚 Full documentation: smartswitch.readthedocs.io

User Guides:

• Installation
• Quick Start
• Basic Usage

Feature Guides:

• Named Handlers - Function registry patterns
• API Discovery - Introspection and hierarchies
• Best Practices - Production patterns

Plugin System:

• Plugin Overview - Understanding plugins
• Plugin Development - Create custom plugins
• Logging Plugin - Call history tracking

Reference:

• API Reference - Complete API docs
• Architecture - Internal design

All examples in documentation are tested - They come directly from our test suite with 82% coverage.

License

MIT

Contributing

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

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