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Python Code Samples

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3 matches
OOP & classes medium

How to Lazy Load an Expensive Attribute with a Proxy in Python

This code shows a Proxy class that lazily loads an ExpensiveResource only when first accessed, caching it for subsequent uses.

lazy-loading proxy properties
Python 
class ExpensiveResource:
    def __init__(self, name):
        self.name = name
        print(f"Expensive resource '{name}' created (e.g., DB connection)")

    def use(self):
        return f"Using {self.name}"

class Proxy:
    def __init__(self, name):
        self._name = name
        self._resource = None

    @p…
15 0 Open
System design patterns medium

How to Build a Sidecar Logging Proxy in Python

Wrap any object with a proxy that transparently logs every method call, arguments, return value, and execution time to a file — mimicking a sidecar pattern.

proxy logging sidecar
Python 
import logging
import time
from datetime import datetime


class LoggingProxy:
    """Sidecar-style proxy that logs all calls to a wrapped object."""

    def __init__(self, target, log_file="proxy.log"):
        self._target = target
        logging.basicConfig(
            filename=log_file,
            level=loggin…
15 0 Open
System design patterns medium

Lazy loading with a proxy in Python: defer expensive service creation

A lazy proxy defers creating an expensive service object until its method is first called, then caches it for reuse.

proxy lazy-loading design-patterns
Python 
import time
import random


class ExpensiveService:
    def __init__(self, name):
        self.name = name
        print(f"Creating expensive service: {self.name}")

    def fetch_data(self):
        time.sleep(1)
        return f"Data from {self.name}: {random.randint(1, 100)}"


class LazyProxy:
    def __init__(sel…
15 0 Open

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