Python Code
Samples
Easy snippets you can copy, study, and run in the browser editor.
How to Implement an Outbox Pattern Mock in Python
This code demonstrates a simple in-memory outbox pattern mock for publishing domain events and tracking pending events until they are marked as published.
from dataclasses import dataclass, field
from datetime import datetime
from uuid import uuid4
@dataclass
class DomainEvent:
event_id: str = field(default_factory=lambda: str(uuid4()))
occurred_at: datetime = field(default_factory=datetime.utcnow)
class Outbox:
def __init__(self):
self._events =…How to Mock a GraphQL Backend in Python
Create an in-memory GraphQL mock backend using dataclasses and resolver methods returning plain dictionaries.
from dataclasses import dataclass, asdict
from typing import Any, Dict, List
@dataclass
class Product:
id: int
name: str
price: float
@dataclass
class User:
id: int
username: str
class MockGraphQLBackend:
def __init__(self) -> None:
self.products = [
Product(id=1, name…How to Mock Partition Pruning in Python
A dataclass-based mock that filters partitions by year and month to emulate Spark's partition pruning logic.
from dataclasses import dataclass
from typing import List
@dataclass(frozen=True)
class Partition:
id: int
year: int
month: int
class PartitionPruner:
"""Mock partition pruning: only keep partitions that match the filter."""
def __init__(self, partitions: List[Partition]):
self._partiti…Modeling a Hive Metastore Table Schema in Python
A dataclass that mimics a Hive metastore table schema—columns, partition keys, storage format, and location—with helper methods for description and mutation.
from dataclasses import dataclass, field
from typing import Dict, List, Optional
@dataclass
class HiveTable:
"""Simple mock of a Hive metastore table schema."""
name: str
database: str = "default"
columns: List[Dict[str, str]] = field(default_factory=list)
partition_keys: List[Dict[str, str]] = f…How to Build a Data Validation Schema in Python
Create a lightweight validation schema using dataclasses and lambda validators to check fields in a dictionary.
import re
from dataclasses import dataclass, field
from typing import Any, Callable
@dataclass
class Field:
name: str
validator: Callable[[Any], bool]
required: bool = True
def validate(self, value: Any) -> bool:
if not self.required and value is None:
return True
return …How to Define a Mock Primary Metric in Python
Define a mock primary metric object with a name, value, and unit, and serialize it to a dictionary for experimentation and testing.
class Metric:
def __init__(self, name, value, unit=None):
self.name = name
self.value = value
self.unit = unit
def to_dict(self):
result = {"name": self.name, "value": self.value}
if self.unit:
result["unit"] = self.unit
return result
def __repr…How to Replicate Data Across All Shards in Python
Mocks a global table that replicates a key-value pair to every shard, ensuring reads return the same value from any shard.
from dataclasses import dataclass
from typing import Dict, List
@dataclass
class Shard:
id: str
data: Dict[str, int]
class GlobalTable:
def __init__(self, shards: List[Shard]):
self._shards = {s.id: s for s in shards}
def set_value(self, key: str, value: int) -> None:
"""Replicate …Rebalance Shard Ranges Across Nodes in Python
A mock rebalancing function that shuffles shard ranges and distributes them evenly across nodes using round-robin assignment.
import random
from dataclasses import dataclass
@dataclass
class Shard:
id: int
start: int
end: int
def rebalance_shards(shards: list[Shard], node_count: int) -> dict[int, list[Shard]]:
"""Mock rebalancing of shard ranges across nodes."""
all_ranges = [(s.start, s.end) for s in shards]
random…How to Build a Simple Data Helper Class in Python
A beginner-friendly DataHelper class that stores Python dataclass objects as JSON records to disk, with load, add, and save methods.
import json
from dataclasses import dataclass, asdict
from pathlib import Path
@dataclass
class User:
name: str
age: int
email: str
class DataHelper:
def __init__(self, filepath: str = "data.json"):
self.filepath = Path(filepath)
self._data = self._load()
def _load(self) -> l…How to Build a Synthetic Monitor Mock in Python
Simulates a synthetic monitoring system in Python that collects latency samples, averages them, and reports service status as UP or DEGRADED.
import random
import time
from dataclasses import dataclass, field
from statistics import mean
@dataclass
class SyntheticMonitor:
service: str
endpoint: str
latency_ms: list[float] = field(default_factory=list)
def check(self) -> float:
latency = random.uniform(50.0, 250.0)
self.late…How to Mock a CI Pipeline with Build, Test, and Deploy Stages in Python
Simulate a three-stage CI pipeline (build, test, deploy) in Python with random pass/fail logic, early exit on failure, and measured stage durations.
import time
import random
from dataclasses import dataclass
@dataclass
class StageResult:
name: str
status: str
duration: float
def run_stage(name: str, success_chance: float = 0.9) -> StageResult:
"""Simulate a pipeline stage with random success/failure."""
start = time.time()
time.sleep(r…How to Mock a Dockerfile Multi-Stage Build in Python
Simulate a Dockerfile multi-stage build process in Python using dataclasses to validate stage ordering and file availability before you write the real Dockerfile.
from dataclasses import dataclass
from pathlib import Path
@dataclass
class BuildStage:
name: str
base_image: str
files: list[str]
commands: list[str]
def run_build(stage: BuildStage, context_dir: Path):
print(f"=== Stage: {stage.name} (base: {stage.base_image}) ===")
for file in stage.file…How to Mock a Feature Flag Rollout Percentage in Python
Simulate a percentage-based feature flag rollout by hashing a user ID to deterministically enable features for a subset of users.
import random
from dataclasses import dataclass
@dataclass
class FeatureFlag:
name: str
rollout_percentage: int
def is_feature_enabled(feature_flag: FeatureFlag, user_id: str) -> bool:
hashed_id = hash(user_id) % 100
return hashed_id < feature_flag.rollout_percentage
if __name__ == "__main__":
…How to Mock a GitHub Actions Workflow in Python
Build a dataclass-based model of a GitHub Actions workflow and simulate its execution to validate steps and outputs before deployment.
import json
from dataclasses import dataclass, asdict
from typing import List, Dict, Any
@dataclass
class Step:
name: str
run: str
@dataclass
class Job:
name: str
steps: List[Step]
runs_on: str = "ubuntu-latest"
@dataclass
class Workflow:
name: str
jobs: List[Job]
def to_github_a…How to Replace Fields in an Immutable Dataclass in Python
Create a new copy of a frozen dataclass with selected fields changed, leaving the original unchanged.
from dataclasses import dataclass, replace
@dataclass(frozen=True)
class ServerConfig:
name: str
cpu: int = 2
ram: int = 4096
tags: tuple = ()
original = ServerConfig("web-01", cpu=4, tags=("env:prod",))
updated = replace(original, ram=8192, tags=("env:prod", "region:us-east"))
print("Original:", …How to Roll Back to a Previous Image Tag in Python
A dataclass-based mock registry that tracks image tag history and rolls back to the previous tag, useful for deployment rollback logic.
"""Demonstrates a rollback pattern for a Docker-style image tag registry."""
from dataclasses import dataclass, field
@dataclass
class ImageRegistry:
"""A minimal mock registry tracking current tags per image."""
tags: dict[str, list[str]] = field(default_factory=dict)
def push(self, image: str, tag: …Browse by section
Each section groups closely related Python snippets.
Guide: free Python code samples library
Copy-ready Python snippets for learners and developers
PythonSkillset code samples are short, focused examples organised by topic and difficulty. Every snippet is server-rendered HTML — readable by search engines and easy to copy. Open any sample, read the notes, copy the code, then press Try in editor to run it in the browser with Pyodide.
How to use this library
- Pick a topic section — strings, lists, files, functions, and more
- Open a sample, read How it works, and copy the code block
- Run it in the IDE, tweak values, then take a related quiz or tutorial lesson
Samples vs tutorials and challenges
Samples are quick reference — one concept per page. For step-by-step teaching, use our Python tutorials. To test yourself, try quizzes or coding challenges. Clean up style with the Python formatter.