Merge pull request #441 from realpython/python-type-hints-multiple-types

Code files for Type Hints tutorial

python-type-hints-multiple-types/01_type_hints_for_one_piece_of_data.py

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+def parse_email(email_address: str) -> str | None:
+    if "@" in email_address:
+        username, domain = email_address.split("@")
+        return username
+    return None
+
+
+# from typing import Union
+# def parse_email(email_address: str) -> Union[str, None]:
+#     if "@" in email_address:
+#         username, domain = email_address.split("@")
+#         return username
+#     return None

python-type-hints-multiple-types/02_type_hints_for_multiple_pieces_of_data.py

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+def parse_email(email_address: str) -> tuple[str, str] | None:
+    if "@" in email_address:
+        username, domain = email_address.split("@")
+        return username, domain
+    return None
+
+
+# from typing import Tuple, Union
+# def parse_email(email_address: str) -> Union[Tuple[str, str], None]:
+#     if "@" in email_address:
+#         username, domain = email_address.split("@")
+#         return username, domain
+#     return None

python-type-hints-multiple-types/03_type_hints_for_callback.py

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+from collections.abc import Callable
+from typing import Any
+
+
+def apply_func(func: Callable[..., Any], *args: Any) -> Any:
+    return func(*args)
+
+
+def parse_email(email_address: str) -> tuple[str, str] | None:
+    if "@" in email_address:
+        username, domain = email_address.split("@")
+        return username, domain
+    return None
+
+
+apply_func(parse_email, "[email protected]")

python-type-hints-multiple-types/04_type_hints_for_factory_function.py

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+import functools
+import time
+from collections.abc import Callable
+from typing import Any
+
+
+def timeit(function: Callable[..., Any]) -> Callable[..., Any]:
+    @functools.wraps(function)
+    def wrapper(*args, **kwargs):
+        start = time.perf_counter()
+        result = function(*args, **kwargs)
+        end = time.perf_counter()
+        print(f"{function.__name__}() finished in {end - start:.10f}s")
+        return result
+
+    return wrapper
+
+
+@timeit
+def parse_email(email_address: str) -> tuple[str, str] | None:
+    if "@" in email_address:
+        username, domain = email_address.split("@")
+        return username, domain
+    return None
+
+
+username, domain = parse_email("[email protected]")
+print(username, domain)

python-type-hints-multiple-types/05_type_hints_for_generator.py

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+from collections.abc import Generator, Iterator
+
+
+def parse_email() -> Generator[tuple[str, str], str, str]:
+    sent = yield "", ""
+    while sent != "":
+        if "@" in sent:
+            username, domain = sent.split("@")
+            sent = yield username, domain
+        else:
+            sent = yield "invalid email"
+    return "Done"
+
+
+generator = parse_email()
+next(generator)
+generator.send("[email protected]")
+generator.send("realpython")
+try:
+    generator.send("")
+except StopIteration as ex:
+    print(ex.value)
+
+
+def parse_emails(emails: list[str]) -> Iterator[tuple[str, str]]:
+    for email in emails:
+        if "@" in email:
+            username, domain = email.split("@")
+            yield username, domain
+
+
+# from collections.abc import Iterable
+# def parse_emails(emails: Iterable[str]) -> Iterable[tuple[str, str]]:
+#     for email in emails:
+#         if "@" in email:
+#             username, domain = email.split("@")
+#             yield username, domain

python-type-hints-multiple-types/06_type_aliases.py

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+from typing import TypeAlias
+
+
+EmailComponents: TypeAlias = tuple[str, str] | None
+
+
+def parse_email(email_address: str) -> EmailComponents:
+    if "@" in email_address:
+        username, domain = email_address.split("@")
+        return username, domain
+    return None

python-type-hints-multiple-types/07_static_type_checking.py

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+def parse_email(email_address: str) -> tuple[str, str] | None:
+    if "@" in email_address:
+        username, domain = email_address.split("@")
+        return username, domain
+    return None

python-type-hints-multiple-types/README.md

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+# How to Use Type Hints for Multiple Return Types in Python
+
+This folder contains sample code for the [How to Use Type Hints for Multiple Return Types in Python](https://realpython.com/python-type-hints-multiple-types/) tutorial on Real Python.
+
+## Installation
+
+Some of the code requires the following third-party library:
+
+- [`mypy`](https://pypi.org/project/mypy/)
+
+To install it into a [virtual environment](https://realpython.com/python-virtual-environments-a-primer/), type the following commands:
+
+```shell
+$ python3 -m venv venv/
+$ source venv/bin/activate
+(venv) $ python -m pip install -r requirements.txt
+```

python-type-hints-multiple-types/requirements.txt

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+mypy==1.5.1
+mypy-extensions==1.0.0
+typing_extensions==4.8.0