Sample code for: Python 3.15: Cool New Features for You to Try

pyproject.toml

@@ -9,6 +9,7 @@ exclude = [
     "agents-md/run1_main.py",
     "python315-frozendict/",
     "python315-lazy-imports",
+    "python315-new-features",
     "ai-benchmark"
 ]
 

python315-new-features/README.md

@@ -0,0 +1,3 @@
+# Python 3.15: Cool New Features for You to Try
+
+This folder provides the code examples for the Real Python tutorial [Python 3.15: Cool New Features for You to Try](https://realpython.com/python315-new-features/)

python315-new-features/ctxmgr.py

@@ -0,0 +1,15 @@
+from contextlib import contextmanager
+
+@contextmanager
+def logged(label):
+    print(f"enter {label}")
+    yield
+    print(f"exit {label}")
+
+@logged("reading")
+def read_lines():
+    yield "first"
+    yield "second"
+
+for line in read_lines():
+    print(line)

python315-new-features/lazy_json.py

@@ -0,0 +1,8 @@
+import sys
+
+lazy import json
+
+print("json loaded:", "json" in sys.modules)
+config = json.dumps({"theme": "dark", "autosave": True})
+print("json loaded:", "json" in sys.modules)
+print(config)

python315-new-features/menu.txt

@@ -0,0 +1 @@
+Crème brûlée — 7 €

python315-new-features/python315_in_15_lines.py

@@ -0,0 +1,18 @@
+import sys
+from pathlib import Path
+lazy import json
+
+defaults = frozendict({"theme": "light", "autosave": True})
+MISSING = sentinel("MISSING")
+
+def resolve(overrides, name, default=MISSING):
+    value = (defaults | overrides).get(name, default)
+    return "unset" if value is MISSING else value
+
+profiles = [{"theme": "crème brûlée"}, {"autosave": False}]
+merged = {**profile for profile in profiles}
+print("json imported:", "json" in sys.modules)
+Path("user.json").write_text(json.dumps(defaults | merged, ensure_ascii=False))
+print("json imported:", "json" in sys.modules)
+print("theme:", resolve(merged, "theme"), "| font:", resolve(merged, "font"))
+print(Path("user.json").read_text())

python315-new-features/requirements.txt

@@ -0,0 +1 @@
+pyright==1.1.414

python315-new-features/typeddict.py

@@ -0,0 +1,14 @@
+from typing import TypedDict
+
+class Movie(TypedDict, closed=True):
+    title: str
+    year: int
+
+class Headers(TypedDict, extra_items=str):
+    content_type: str
+
+movie: Movie = {"title": "Brazil", "year": 1985, "rating": 8.0}
+headers: Headers = {"content_type": "text/html", "x-trace-id": "abc123"}
+bad_headers: Headers = {"content_type": "text/html", "x-retries": 3}
+
+print(Movie.__closed__, Headers.__extra_items__)

python315-new-features/typeform_check.py

@@ -0,0 +1,11 @@
+from typing import TypeForm, reveal_type
+
+def parse_old[T](value: str, typ: type[T]) -> T: ...
+
+def parse_new[T](value: str, typ: TypeForm[T]) -> T: ...
+
+reveal_type(parse_old("42", int))
+reveal_type(parse_old("42", int | None))
+reveal_type(parse_new("42", int | None))
+reveal_type(parse_new("42", list[int]))
+parse_new("42", 42)

python315-new-features/wordstats.py

@@ -0,0 +1,8 @@
+from collections import Counter
+
+def most_common_words(text, n=3):
+    words = [word.strip(".,").lower() for word in text.split()]
+    return Counter(words).most_common(n)
+
+sample = "The quick brown fox jumps over the lazy dog. " * 100_000
+print(most_common_words(sample))