Merge branch '2025-context'

Author: egges

2025/context/.python-version

@@ -0,0 +1 @@
+3.13

2025/context/before.py

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+import logging
+from db import db_session, init_db, Article, Session
+
+# -----------------------------------
+# Application Logic
+# -----------------------------------
+
+def render_article(article_id: int, db: Session, logger: logging.Logger, api_key: str) -> str:
+    article = db.query(Article).filter(Article.id == article_id).first()
+    if not article:
+        logger.error(f"Article {article_id} not found.")
+        return "<p>Article not found.</p>"
+
+    logger.info(f"Rendering article {article_id} using API key {api_key[:4]}...")
+    html = f"<h1>{article.title}</h1><p>{article.body}</p>"
+    return html
+
+def main() -> None:
+    logging.basicConfig(level=logging.INFO)
+    logger = logging.getLogger("app")
+
+    init_db()
+
+    with db_session() as session:
+
+        api_key = "abcdef123456"
+
+        html = render_article(1, session, logger, api_key)
+        print(html)
+
+        html = render_article(999, session, logger, api_key)  # not found
+        print(html)
+
+
+if __name__ == "__main__":
+    main()
+
+    

2025/context/context_v1.py

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+import logging
+from dataclasses import dataclass
+from typing import Any
+from db import db_session, init_db, Article , Session
+
+# -----------------------------------
+# Context Object
+# -----------------------------------
+
+@dataclass
+class AppContext:
+    user_id: int
+    db: Session
+    logger: logging.Logger
+    config: dict[str, Any]
+
+# -----------------------------------
+# Application Logic
+# -----------------------------------
+
+def render_article(article_id: int, context: AppContext) -> str:
+    article = context.db.query(Article).filter(Article.id == article_id).first()
+    if not article:
+        context.logger.error(f"Article {article_id} not found.")
+        return "<p>Article not found.</p>"
+
+    context.logger.info(f"Rendering article {article_id}")
+    html = f"<h1>{article.title}</h1><p>{article.body}</p>"
+    return html
+# -----------------------------------
+# Entry Point
+# -----------------------------------
+
+def main() -> None:
+    logging.basicConfig(level=logging.INFO)
+    logger = logging.getLogger("app")
+
+    init_db()
+
+    with db_session() as session:
+        context = AppContext(
+            user_id=42,
+            db=session,
+            logger=logger,
+            config={"api_key": "abcdef123456"},
+        )
+
+        html = render_article(1, context)
+        print(html)
+
+        html = render_article(999, context)  # not found
+        print(html)
+
+if __name__ == "__main__":
+    main()
+
+    

2025/context/context_v2.py

@@ -0,0 +1,78 @@
+import logging
+from dataclasses import dataclass
+from typing import Protocol, Any
+from db import db_session, init_db, Article
+
+# -----------------------------------
+# Protocols for loose coupling
+# -----------------------------------
+
+class LoggerProtocol(Protocol):
+    def info(self, msg: str, *args: Any, **kwargs: Any) -> None: ...
+    def error(self, msg: str, *args: Any, **kwargs: Any) -> None: ...
+
+class DBProtocol(Protocol):
+    def query(self, *args: Any, **kwargs: Any) -> Any: ...
+
+# -----------------------------------
+# Context Object
+# -----------------------------------
+
+@dataclass
+class AppContext:
+    user_id: int
+    db: DBProtocol
+    logger: LoggerProtocol
+    config: dict[str, Any]
+
+# -----------------------------------
+# Application Logic
+# -----------------------------------
+
+def render_article(article_id: int, db: DBProtocol, logger: LoggerProtocol) -> str:
+    article = db.query(Article).filter(Article.id == article_id).first()
+    if not article:
+        logger.error(f"Article {article_id} not found.")
+        return "<p>Article not found.</p>"
+
+    logger.info(f"Rendering article {article_id}")
+    html = f"<h1>{article.title}</h1><p>{article.body}</p>"
+    return html
+
+def send_to_external_service(html: str, api_key: str) -> None:
+    print(f"Sending to API with key {api_key[:4]}... Content: {html[:30]}...")
+
+def publish_article(article_id: int, context: AppContext) -> None:
+    html = render_article(
+        article_id,
+        db=context.db,
+        logger=context.logger,
+    )
+    send_to_external_service(html, context.config['api_key'])
+
+# -----------------------------------
+# Entry Point
+# -----------------------------------
+
+def main() -> None:
+    logging.basicConfig(level=logging.INFO)
+    logger = logging.getLogger("app")
+
+    init_db()
+
+    with db_session() as session:
+        context = AppContext(
+            user_id=42,
+            db=session,
+            logger=logger,
+            config={"api_key": "abcdef123456"},
+        )
+
+        publish_article(1, context)
+        publish_article(2, context)
+        publish_article(999, context)  # Not found example
+
+if __name__ == "__main__":
+    main()
+
+    

2025/context/db.py

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+from contextlib import contextmanager
+from sqlalchemy import Column, Integer, String, create_engine
+from sqlalchemy.orm import Session, declarative_base, sessionmaker
+from typing import Generator
+
+Base = declarative_base()
+
+class Article(Base):
+    __tablename__ = "articles"
+
+    id = Column(Integer, primary_key=True)
+    title = Column(String)
+    body = Column(String)
+
+# SQLite in-memory DB for demo purposes
+engine = create_engine("sqlite:///:memory:", echo=False, future=True)
+SessionLocal = sessionmaker(bind=engine, expire_on_commit=False)
+
+def init_db() -> None:
+    Base.metadata.create_all(bind=engine)
+    with db_session() as session:
+        session.add_all([
+            Article(id=1, title="Hello", body="World!"),
+            Article(id=2, title="Python", body="Is Awesome"),
+        ])
+        session.commit()
+
+@contextmanager
+def db_session() -> Generator[Session, None, None]:
+    session = SessionLocal()
+    try:
+        yield session
+    finally:
+        session.close()

2025/context/pyproject.toml

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+[project]
+name = "context-object-example"
+version = "0.1.0"
+description = "An example of the Context Object Pattern using SQLite and SQLAlchemy"
+requires-python = ">=3.13"
+dependencies = [
+    "sqlalchemy>=2.0",
+]