Pythonの型ヒントと共に進化するコード Advent Calendar 2025

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@inetcpl

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Recusotmer でエンジニアをしている 𝕂' こと Yuki です。

本アドベントカレンダーでは、
「動くけれど触りたくない」Python コードが型ヒントと共に堅牢なコードへ進化する過程 を 25 日間で追います！

脆いコードに対して TypedDict、Union、Protocol、Callable、TypeVar など多様な型ヒントを漸進的に取り入れ、後半では簡易的な自作の Result 型も実装し、最終的にはパッケージ化して外部公開可能な品質まで引き上げます。

型チェッカー（mypy）と仲良くなり、実行時エラーを開発時に潰す実践的なリファクタリング手法を紹介します。
このアドベントカレンダーを通じて Python における型の重要性を共有できたらと思います！

How to join the calendar

You can join the calendar by selecting an available date and registering the URL of the article you wish to link to. If a slot is available, you can go back to a past date to join!

Series 1

Sunday	Monday	Tuesday	Wednesday	Thursday	Friday	Saturday
30	@inetcpl なぜ Recusotmer が型を語るのか Overwrite Title URL You can post either your article on Qiita or your blog post. About reserved posting If you register a secret article by the day before the same day, it will be automatically published around 7:00 on the same day. About posting period Only articles submitted after October 31, 2025 can be registered. (Secret articles can be registered anytime articles are posted.) When you participate, we will assume that you have agreed to the terms of use	@inetcpl 本連載で得られること・型チェッカーの基本的な紹介など Overwrite Title URL You can post either your article on Qiita or your blog post. About reserved posting If you register a secret article by the day before the same day, it will be automatically published around 7:00 on the same day. About posting period Only articles submitted after October 31, 2025 can be registered. (Secret articles can be registered anytime articles are posted.) When you participate, we will assume that you have agreed to the terms of use	@inetcpl 進化対象の「脆いコード」お披露目回 Overwrite Title URL You can post either your article on Qiita or your blog post. About reserved posting If you register a secret article by the day before the same day, it will be automatically published around 7:00 on the same day. About posting period Only articles submitted after October 31, 2025 can be registered. (Secret articles can be registered anytime articles are posted.) When you participate, we will assume that you have agreed to the terms of use	@inetcpl TypedDict Overwrite Title URL You can post either your article on Qiita or your blog post. About reserved posting If you register a secret article by the day before the same day, it will be automatically published around 7:00 on the same day. About posting period Only articles submitted after October 31, 2025 can be registered. (Secret articles can be registered anytime articles are posted.) When you participate, we will assume that you have agreed to the terms of use	@inetcpl Union, Optional Overwrite Title URL You can post either your article on Qiita or your blog post. About reserved posting If you register a secret article by the day before the same day, it will be automatically published around 7:00 on the same day. About posting period Only articles submitted after October 31, 2025 can be registered. (Secret articles can be registered anytime articles are posted.) When you participate, we will assume that you have agreed to the terms of use	@inetcpl NewType, TypeAlias Overwrite Title URL You can post either your article on Qiita or your blog post. About reserved posting If you register a secret article by the day before the same day, it will be automatically published around 7:00 on the same day. About posting period Only articles submitted after October 31, 2025 can be registered. (Secret articles can be registered anytime articles are posted.) When you participate, we will assume that you have agreed to the terms of use
@inetcpl ABC — Abstract Base Classes Overwrite Title URL You can post either your article on Qiita or your blog post. About reserved posting If you register a secret article by the day before the same day, it will be automatically published around 7:00 on the same day. About posting period Only articles submitted after October 31, 2025 can be registered. (Secret articles can be registered anytime articles are posted.) When you participate, we will assume that you have agreed to the terms of use	@inetcpl Protocol Overwrite Title URL You can post either your article on Qiita or your blog post. About reserved posting If you register a secret article by the day before the same day, it will be automatically published around 7:00 on the same day. About posting period Only articles submitted after October 31, 2025 can be registered. (Secret articles can be registered anytime articles are posted.) When you participate, we will assume that you have agreed to the terms of use	@inetcpl モジュール分割 Overwrite Title URL You can post either your article on Qiita or your blog post. About reserved posting If you register a secret article by the day before the same day, it will be automatically published around 7:00 on the same day. About posting period Only articles submitted after October 31, 2025 can be registered. (Secret articles can be registered anytime articles are posted.) When you participate, we will assume that you have agreed to the terms of use	@inetcpl dataclasses, ClassVar Overwrite Title URL You can post either your article on Qiita or your blog post. About reserved posting If you register a secret article by the day before the same day, it will be automatically published around 7:00 on the same day. About posting period Only articles submitted after October 31, 2025 can be registered. (Secret articles can be registered anytime articles are posted.) When you participate, we will assume that you have agreed to the terms of use	@inetcpl コレクション抽象型（Mapping） Overwrite Title URL You can post either your article on Qiita or your blog post. About reserved posting If you register a secret article by the day before the same day, it will be automatically published around 7:00 on the same day. About posting period Only articles submitted after October 31, 2025 can be registered. (Secret articles can be registered anytime articles are posted.) When you participate, we will assume that you have agreed to the terms of use	@inetcpl Final Overwrite Title URL You can post either your article on Qiita or your blog post. About reserved posting If you register a secret article by the day before the same day, it will be automatically published around 7:00 on the same day. About posting period Only articles submitted after October 31, 2025 can be registered. (Secret articles can be registered anytime articles are posted.) When you participate, we will assume that you have agreed to the terms of use	@inetcpl from __future__ import annotations（と、TYPE_CHECKING） Overwrite Title URL You can post either your article on Qiita or your blog post. About reserved posting If you register a secret article by the day before the same day, it will be automatically published around 7:00 on the same day. About posting period Only articles submitted after October 31, 2025 can be registered. (Secret articles can be registered anytime articles are posted.) When you participate, we will assume that you have agreed to the terms of use
@inetcpl コラム回：Typer のすゝめ Overwrite Title URL You can post either your article on Qiita or your blog post. About reserved posting If you register a secret article by the day before the same day, it will be automatically published around 7:00 on the same day. About posting period Only articles submitted after October 31, 2025 can be registered. (Secret articles can be registered anytime articles are posted.) When you participate, we will assume that you have agreed to the terms of use	@inetcpl Self, ReadOnly Overwrite Title URL You can post either your article on Qiita or your blog post. About reserved posting If you register a secret article by the day before the same day, it will be automatically published around 7:00 on the same day. About posting period Only articles submitted after October 31, 2025 can be registered. (Secret articles can be registered anytime articles are posted.) When you participate, we will assume that you have agreed to the terms of use	@inetcpl TypeVar で実現する Generics Overwrite Title URL You can post either your article on Qiita or your blog post. About reserved posting If you register a secret article by the day before the same day, it will be automatically published around 7:00 on the same day. About posting period Only articles submitted after October 31, 2025 can be registered. (Secret articles can be registered anytime articles are posted.) When you participate, we will assume that you have agreed to the terms of use	@inetcpl ParamSpec, Callable Overwrite Title URL You can post either your article on Qiita or your blog post. About reserved posting If you register a secret article by the day before the same day, it will be automatically published around 7:00 on the same day. About posting period Only articles submitted after October 31, 2025 can be registered. (Secret articles can be registered anytime articles are posted.) When you participate, we will assume that you have agreed to the terms of use	@inetcpl Type Narrowing（isinstance, TypeGuard, TypeIs） Overwrite Title URL You can post either your article on Qiita or your blog post. About reserved posting If you register a secret article by the day before the same day, it will be automatically published around 7:00 on the same day. About posting period Only articles submitted after October 31, 2025 can be registered. (Secret articles can be registered anytime articles are posted.) When you participate, we will assume that you have agreed to the terms of use	@inetcpl コラム回：reveal_type Overwrite Title URL You can post either your article on Qiita or your blog post. About reserved posting If you register a secret article by the day before the same day, it will be automatically published around 7:00 on the same day. About posting period Only articles submitted after October 31, 2025 can be registered. (Secret articles can be registered anytime articles are posted.) When you participate, we will assume that you have agreed to the terms of use	@inetcpl Enum, assert_never Overwrite Title URL You can post either your article on Qiita or your blog post. About reserved posting If you register a secret article by the day before the same day, it will be automatically published around 7:00 on the same day. About posting period Only articles submitted after October 31, 2025 can be registered. (Secret articles can be registered anytime articles are posted.) When you participate, we will assume that you have agreed to the terms of use
@inetcpl 簡易な Result 型を自作する Overwrite Title URL You can post either your article on Qiita or your blog post. About reserved posting If you register a secret article by the day before the same day, it will be automatically published around 7:00 on the same day. About posting period Only articles submitted after October 31, 2025 can be registered. (Secret articles can be registered anytime articles are posted.) When you participate, we will assume that you have agreed to the terms of use	@inetcpl Literal, Annotated（print卒業） Overwrite Title URL You can post either your article on Qiita or your blog post. About reserved posting If you register a secret article by the day before the same day, it will be automatically published around 7:00 on the same day. About posting period Only articles submitted after October 31, 2025 can be registered. (Secret articles can be registered anytime articles are posted.) When you participate, we will assume that you have agreed to the terms of use	@inetcpl 型情報を外部に公開する（py.typed, typeshed） Overwrite Title URL You can post either your article on Qiita or your blog post. About reserved posting If you register a secret article by the day before the same day, it will be automatically published around 7:00 on the same day. About posting period Only articles submitted after October 31, 2025 can be registered. (Secret articles can be registered anytime articles are posted.) When you participate, we will assume that you have agreed to the terms of use	@inetcpl コラム回：mypy strict モードを深堀りする Overwrite Title URL You can post either your article on Qiita or your blog post. About reserved posting If you register a secret article by the day before the same day, it will be automatically published around 7:00 on the same day. About posting period Only articles submitted after October 31, 2025 can be registered. (Secret articles can be registered anytime articles are posted.) When you participate, we will assume that you have agreed to the terms of use	@inetcpl なぜ私たちはPythonで型を書くのか Overwrite Title URL You can post either your article on Qiita or your blog post. About reserved posting If you register a secret article by the day before the same day, it will be automatically published around 7:00 on the same day. About posting period Only articles submitted after October 31, 2025 can be registered. (Secret articles can be registered anytime articles are posted.) When you participate, we will assume that you have agreed to the terms of use	26	27

@inetcpl
なぜ Recusotmer が型を語るのか
Overwrite
Title
URL
You can post either your article on Qiita or your blog post.
About reserved posting
If you register a secret article by the day before the same day, it will be automatically published around 7:00 on the same day.
About posting period
Only articles submitted after October 31, 2025 can be registered. (Secret articles can be registered anytime articles are posted.)
When you participate, we will assume that you have agreed to the terms of use
@inetcpl
本連載で得られること・型チェッカーの基本的な紹介など
Overwrite
Title
URL
You can post either your article on Qiita or your blog post.
About reserved posting
If you register a secret article by the day before the same day, it will be automatically published around 7:00 on the same day.
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Only articles submitted after October 31, 2025 can be registered. (Secret articles can be registered anytime articles are posted.)
When you participate, we will assume that you have agreed to the terms of use
@inetcpl
進化対象の「脆いコード」お披露目回
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If you register a secret article by the day before the same day, it will be automatically published around 7:00 on the same day.
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@inetcpl
TypedDict
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@inetcpl
Union, Optional
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@inetcpl
NewType, TypeAlias
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@inetcpl
ABC — Abstract Base Classes
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@inetcpl
Protocol
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@inetcpl
モジュール分割
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@inetcpl
dataclasses, ClassVar
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@inetcpl
コレクション抽象型（Mapping）
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@inetcpl
Final
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from __future__ import annotations（と、TYPE_CHECKING）
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@inetcpl
コラム回：Typer のすゝめ
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@inetcpl
Self, ReadOnly
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TypeVar で実現する Generics
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ParamSpec, Callable
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Type Narrowing（isinstance, TypeGuard, TypeIs）
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コラム回：reveal_type
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@inetcpl
Enum, assert_never
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@inetcpl
簡易な Result 型を自作する
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Only articles submitted after October 31, 2025 can be registered. (Secret articles can be registered anytime articles are posted.)
When you participate, we will assume that you have agreed to the terms of use
@inetcpl
Literal, Annotated（print卒業）
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If you register a secret article by the day before the same day, it will be automatically published around 7:00 on the same day.
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@inetcpl
型情報を外部に公開する（py.typed, typeshed）
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@inetcpl
コラム回：mypy strict モードを深堀りする
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@inetcpl
なぜ私たちはPythonで型を書くのか
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When you participate, we will assume that you have agreed to the terms of use

Sunday	Monday	Tuesday	Wednesday	Thursday	Friday	Saturday
30	@inetcpl なぜ Recusotmer が型を語るのか Overwrite Title URL You can post either your article on Qiita or your blog post. About reserved posting If you register a secret article by the day before the same day, it will be automatically published around 7:00 on the same day. About posting period Only articles submitted after October 31, 2025 can be registered. (Secret articles can be registered anytime articles are posted.) When you participate, we will assume that you have agreed to the terms of use	@inetcpl 本連載で得られること・型チェッカーの基本的な紹介など Overwrite Title URL You can post either your article on Qiita or your blog post. About reserved posting If you register a secret article by the day before the same day, it will be automatically published around 7:00 on the same day. About posting period Only articles submitted after October 31, 2025 can be registered. (Secret articles can be registered anytime articles are posted.) When you participate, we will assume that you have agreed to the terms of use	@inetcpl 進化対象の「脆いコード」お披露目回 Overwrite Title URL You can post either your article on Qiita or your blog post. About reserved posting If you register a secret article by the day before the same day, it will be automatically published around 7:00 on the same day. About posting period Only articles submitted after October 31, 2025 can be registered. (Secret articles can be registered anytime articles are posted.) When you participate, we will assume that you have agreed to the terms of use	@inetcpl TypedDict Overwrite Title URL You can post either your article on Qiita or your blog post. About reserved posting If you register a secret article by the day before the same day, it will be automatically published around 7:00 on the same day. About posting period Only articles submitted after October 31, 2025 can be registered. (Secret articles can be registered anytime articles are posted.) When you participate, we will assume that you have agreed to the terms of use	@inetcpl Union, Optional Overwrite Title URL You can post either your article on Qiita or your blog post. About reserved posting If you register a secret article by the day before the same day, it will be automatically published around 7:00 on the same day. About posting period Only articles submitted after October 31, 2025 can be registered. (Secret articles can be registered anytime articles are posted.) When you participate, we will assume that you have agreed to the terms of use	@inetcpl NewType, TypeAlias Overwrite Title URL You can post either your article on Qiita or your blog post. About reserved posting If you register a secret article by the day before the same day, it will be automatically published around 7:00 on the same day. About posting period Only articles submitted after October 31, 2025 can be registered. (Secret articles can be registered anytime articles are posted.) When you participate, we will assume that you have agreed to the terms of use
@inetcpl ABC — Abstract Base Classes Overwrite Title URL You can post either your article on Qiita or your blog post. About reserved posting If you register a secret article by the day before the same day, it will be automatically published around 7:00 on the same day. About posting period Only articles submitted after October 31, 2025 can be registered. (Secret articles can be registered anytime articles are posted.) When you participate, we will assume that you have agreed to the terms of use	@inetcpl Protocol Overwrite Title URL You can post either your article on Qiita or your blog post. About reserved posting If you register a secret article by the day before the same day, it will be automatically published around 7:00 on the same day. About posting period Only articles submitted after October 31, 2025 can be registered. (Secret articles can be registered anytime articles are posted.) When you participate, we will assume that you have agreed to the terms of use	@inetcpl モジュール分割 Overwrite Title URL You can post either your article on Qiita or your blog post. About reserved posting If you register a secret article by the day before the same day, it will be automatically published around 7:00 on the same day. About posting period Only articles submitted after October 31, 2025 can be registered. (Secret articles can be registered anytime articles are posted.) When you participate, we will assume that you have agreed to the terms of use	@inetcpl dataclasses, ClassVar Overwrite Title URL You can post either your article on Qiita or your blog post. About reserved posting If you register a secret article by the day before the same day, it will be automatically published around 7:00 on the same day. About posting period Only articles submitted after October 31, 2025 can be registered. (Secret articles can be registered anytime articles are posted.) When you participate, we will assume that you have agreed to the terms of use	@inetcpl コレクション抽象型（Mapping） Overwrite Title URL You can post either your article on Qiita or your blog post. About reserved posting If you register a secret article by the day before the same day, it will be automatically published around 7:00 on the same day. About posting period Only articles submitted after October 31, 2025 can be registered. (Secret articles can be registered anytime articles are posted.) When you participate, we will assume that you have agreed to the terms of use	@inetcpl Final Overwrite Title URL You can post either your article on Qiita or your blog post. About reserved posting If you register a secret article by the day before the same day, it will be automatically published around 7:00 on the same day. About posting period Only articles submitted after October 31, 2025 can be registered. (Secret articles can be registered anytime articles are posted.) When you participate, we will assume that you have agreed to the terms of use	@inetcpl from __future__ import annotations（と、TYPE_CHECKING） Overwrite Title URL You can post either your article on Qiita or your blog post. About reserved posting If you register a secret article by the day before the same day, it will be automatically published around 7:00 on the same day. About posting period Only articles submitted after October 31, 2025 can be registered. (Secret articles can be registered anytime articles are posted.) When you participate, we will assume that you have agreed to the terms of use
@inetcpl コラム回：Typer のすゝめ Overwrite Title URL You can post either your article on Qiita or your blog post. About reserved posting If you register a secret article by the day before the same day, it will be automatically published around 7:00 on the same day. About posting period Only articles submitted after October 31, 2025 can be registered. (Secret articles can be registered anytime articles are posted.) When you participate, we will assume that you have agreed to the terms of use	@inetcpl Self, ReadOnly Overwrite Title URL You can post either your article on Qiita or your blog post. About reserved posting If you register a secret article by the day before the same day, it will be automatically published around 7:00 on the same day. About posting period Only articles submitted after October 31, 2025 can be registered. (Secret articles can be registered anytime articles are posted.) When you participate, we will assume that you have agreed to the terms of use	@inetcpl TypeVar で実現する Generics Overwrite Title URL You can post either your article on Qiita or your blog post. About reserved posting If you register a secret article by the day before the same day, it will be automatically published around 7:00 on the same day. About posting period Only articles submitted after October 31, 2025 can be registered. (Secret articles can be registered anytime articles are posted.) When you participate, we will assume that you have agreed to the terms of use	@inetcpl ParamSpec, Callable Overwrite Title URL You can post either your article on Qiita or your blog post. About reserved posting If you register a secret article by the day before the same day, it will be automatically published around 7:00 on the same day. About posting period Only articles submitted after October 31, 2025 can be registered. (Secret articles can be registered anytime articles are posted.) When you participate, we will assume that you have agreed to the terms of use	@inetcpl Type Narrowing（isinstance, TypeGuard, TypeIs） Overwrite Title URL You can post either your article on Qiita or your blog post. About reserved posting If you register a secret article by the day before the same day, it will be automatically published around 7:00 on the same day. About posting period Only articles submitted after October 31, 2025 can be registered. (Secret articles can be registered anytime articles are posted.) When you participate, we will assume that you have agreed to the terms of use	@inetcpl コラム回：reveal_type Overwrite Title URL You can post either your article on Qiita or your blog post. About reserved posting If you register a secret article by the day before the same day, it will be automatically published around 7:00 on the same day. About posting period Only articles submitted after October 31, 2025 can be registered. (Secret articles can be registered anytime articles are posted.) When you participate, we will assume that you have agreed to the terms of use	@inetcpl Enum, assert_never Overwrite Title URL You can post either your article on Qiita or your blog post. About reserved posting If you register a secret article by the day before the same day, it will be automatically published around 7:00 on the same day. About posting period Only articles submitted after October 31, 2025 can be registered. (Secret articles can be registered anytime articles are posted.) When you participate, we will assume that you have agreed to the terms of use
@inetcpl 簡易な Result 型を自作する Overwrite Title URL You can post either your article on Qiita or your blog post. About reserved posting If you register a secret article by the day before the same day, it will be automatically published around 7:00 on the same day. About posting period Only articles submitted after October 31, 2025 can be registered. (Secret articles can be registered anytime articles are posted.) When you participate, we will assume that you have agreed to the terms of use	@inetcpl Literal, Annotated（print卒業） Overwrite Title URL You can post either your article on Qiita or your blog post. About reserved posting If you register a secret article by the day before the same day, it will be automatically published around 7:00 on the same day. About posting period Only articles submitted after October 31, 2025 can be registered. (Secret articles can be registered anytime articles are posted.) When you participate, we will assume that you have agreed to the terms of use	@inetcpl 型情報を外部に公開する（py.typed, typeshed） Overwrite Title URL You can post either your article on Qiita or your blog post. About reserved posting If you register a secret article by the day before the same day, it will be automatically published around 7:00 on the same day. About posting period Only articles submitted after October 31, 2025 can be registered. (Secret articles can be registered anytime articles are posted.) When you participate, we will assume that you have agreed to the terms of use	@inetcpl コラム回：mypy strict モードを深堀りする Overwrite Title URL You can post either your article on Qiita or your blog post. About reserved posting If you register a secret article by the day before the same day, it will be automatically published around 7:00 on the same day. About posting period Only articles submitted after October 31, 2025 can be registered. (Secret articles can be registered anytime articles are posted.) When you participate, we will assume that you have agreed to the terms of use	@inetcpl なぜ私たちはPythonで型を書くのか Overwrite Title URL You can post either your article on Qiita or your blog post. About reserved posting If you register a secret article by the day before the same day, it will be automatically published around 7:00 on the same day. About posting period Only articles submitted after October 31, 2025 can be registered. (Secret articles can be registered anytime articles are posted.) When you participate, we will assume that you have agreed to the terms of use	26	27

@inetcpl
なぜ Recusotmer が型を語るのか
Overwrite
Title
URL
You can post either your article on Qiita or your blog post.
About reserved posting
If you register a secret article by the day before the same day, it will be automatically published around 7:00 on the same day.
About posting period
Only articles submitted after October 31, 2025 can be registered. (Secret articles can be registered anytime articles are posted.)
When you participate, we will assume that you have agreed to the terms of use
@inetcpl
本連載で得られること・型チェッカーの基本的な紹介など
Overwrite
Title
URL
You can post either your article on Qiita or your blog post.
About reserved posting
If you register a secret article by the day before the same day, it will be automatically published around 7:00 on the same day.
About posting period
Only articles submitted after October 31, 2025 can be registered. (Secret articles can be registered anytime articles are posted.)
When you participate, we will assume that you have agreed to the terms of use
@inetcpl
進化対象の「脆いコード」お披露目回
Overwrite
Title
URL
You can post either your article on Qiita or your blog post.
About reserved posting
If you register a secret article by the day before the same day, it will be automatically published around 7:00 on the same day.
About posting period
Only articles submitted after October 31, 2025 can be registered. (Secret articles can be registered anytime articles are posted.)
When you participate, we will assume that you have agreed to the terms of use
@inetcpl
TypedDict
Overwrite
Title
URL
You can post either your article on Qiita or your blog post.
About reserved posting
If you register a secret article by the day before the same day, it will be automatically published around 7:00 on the same day.
About posting period
Only articles submitted after October 31, 2025 can be registered. (Secret articles can be registered anytime articles are posted.)
When you participate, we will assume that you have agreed to the terms of use
@inetcpl
Union, Optional
Overwrite
Title
URL
You can post either your article on Qiita or your blog post.
About reserved posting
If you register a secret article by the day before the same day, it will be automatically published around 7:00 on the same day.
About posting period
Only articles submitted after October 31, 2025 can be registered. (Secret articles can be registered anytime articles are posted.)
When you participate, we will assume that you have agreed to the terms of use
@inetcpl
NewType, TypeAlias
Overwrite
Title
URL
You can post either your article on Qiita or your blog post.
About reserved posting
If you register a secret article by the day before the same day, it will be automatically published around 7:00 on the same day.
About posting period
Only articles submitted after October 31, 2025 can be registered. (Secret articles can be registered anytime articles are posted.)
When you participate, we will assume that you have agreed to the terms of use
@inetcpl
ABC — Abstract Base Classes
Overwrite
Title
URL
You can post either your article on Qiita or your blog post.
About reserved posting
If you register a secret article by the day before the same day, it will be automatically published around 7:00 on the same day.
About posting period
Only articles submitted after October 31, 2025 can be registered. (Secret articles can be registered anytime articles are posted.)
When you participate, we will assume that you have agreed to the terms of use
@inetcpl
Protocol
Overwrite
Title
URL
You can post either your article on Qiita or your blog post.
About reserved posting
If you register a secret article by the day before the same day, it will be automatically published around 7:00 on the same day.
About posting period
Only articles submitted after October 31, 2025 can be registered. (Secret articles can be registered anytime articles are posted.)
When you participate, we will assume that you have agreed to the terms of use
@inetcpl
モジュール分割
Overwrite
Title
URL
You can post either your article on Qiita or your blog post.
About reserved posting
If you register a secret article by the day before the same day, it will be automatically published around 7:00 on the same day.
About posting period
Only articles submitted after October 31, 2025 can be registered. (Secret articles can be registered anytime articles are posted.)
When you participate, we will assume that you have agreed to the terms of use
@inetcpl
dataclasses, ClassVar
Overwrite
Title
URL
You can post either your article on Qiita or your blog post.
About reserved posting
If you register a secret article by the day before the same day, it will be automatically published around 7:00 on the same day.
About posting period
Only articles submitted after October 31, 2025 can be registered. (Secret articles can be registered anytime articles are posted.)
When you participate, we will assume that you have agreed to the terms of use
@inetcpl
コレクション抽象型（Mapping）
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Title
URL
You can post either your article on Qiita or your blog post.
About reserved posting
If you register a secret article by the day before the same day, it will be automatically published around 7:00 on the same day.
About posting period
Only articles submitted after October 31, 2025 can be registered. (Secret articles can be registered anytime articles are posted.)
When you participate, we will assume that you have agreed to the terms of use
@inetcpl
Final
Overwrite
Title
URL
You can post either your article on Qiita or your blog post.
About reserved posting
If you register a secret article by the day before the same day, it will be automatically published around 7:00 on the same day.
About posting period
Only articles submitted after October 31, 2025 can be registered. (Secret articles can be registered anytime articles are posted.)
When you participate, we will assume that you have agreed to the terms of use
@inetcpl
from __future__ import annotations（と、TYPE_CHECKING）
Overwrite
Title
URL
You can post either your article on Qiita or your blog post.
About reserved posting
If you register a secret article by the day before the same day, it will be automatically published around 7:00 on the same day.
About posting period
Only articles submitted after October 31, 2025 can be registered. (Secret articles can be registered anytime articles are posted.)
When you participate, we will assume that you have agreed to the terms of use
@inetcpl
コラム回：Typer のすゝめ
Overwrite
Title
URL
You can post either your article on Qiita or your blog post.
About reserved posting
If you register a secret article by the day before the same day, it will be automatically published around 7:00 on the same day.
About posting period
Only articles submitted after October 31, 2025 can be registered. (Secret articles can be registered anytime articles are posted.)
When you participate, we will assume that you have agreed to the terms of use
@inetcpl
Self, ReadOnly
Overwrite
Title
URL
You can post either your article on Qiita or your blog post.
About reserved posting
If you register a secret article by the day before the same day, it will be automatically published around 7:00 on the same day.
About posting period
Only articles submitted after October 31, 2025 can be registered. (Secret articles can be registered anytime articles are posted.)
When you participate, we will assume that you have agreed to the terms of use
@inetcpl
TypeVar で実現する Generics
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Title
URL
You can post either your article on Qiita or your blog post.
About reserved posting
If you register a secret article by the day before the same day, it will be automatically published around 7:00 on the same day.
About posting period
Only articles submitted after October 31, 2025 can be registered. (Secret articles can be registered anytime articles are posted.)
When you participate, we will assume that you have agreed to the terms of use
@inetcpl
ParamSpec, Callable
Overwrite
Title
URL
You can post either your article on Qiita or your blog post.
About reserved posting
If you register a secret article by the day before the same day, it will be automatically published around 7:00 on the same day.
About posting period
Only articles submitted after October 31, 2025 can be registered. (Secret articles can be registered anytime articles are posted.)
When you participate, we will assume that you have agreed to the terms of use
@inetcpl
Type Narrowing（isinstance, TypeGuard, TypeIs）
Overwrite
Title
URL
You can post either your article on Qiita or your blog post.
About reserved posting
If you register a secret article by the day before the same day, it will be automatically published around 7:00 on the same day.
About posting period
Only articles submitted after October 31, 2025 can be registered. (Secret articles can be registered anytime articles are posted.)
When you participate, we will assume that you have agreed to the terms of use
@inetcpl
コラム回：reveal_type
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Title
URL
You can post either your article on Qiita or your blog post.
About reserved posting
If you register a secret article by the day before the same day, it will be automatically published around 7:00 on the same day.
About posting period
Only articles submitted after October 31, 2025 can be registered. (Secret articles can be registered anytime articles are posted.)
When you participate, we will assume that you have agreed to the terms of use
@inetcpl
Enum, assert_never
Overwrite
Title
URL
You can post either your article on Qiita or your blog post.
About reserved posting
If you register a secret article by the day before the same day, it will be automatically published around 7:00 on the same day.
About posting period
Only articles submitted after October 31, 2025 can be registered. (Secret articles can be registered anytime articles are posted.)
When you participate, we will assume that you have agreed to the terms of use
@inetcpl
簡易な Result 型を自作する
Overwrite
Title
URL
You can post either your article on Qiita or your blog post.
About reserved posting
If you register a secret article by the day before the same day, it will be automatically published around 7:00 on the same day.
About posting period
Only articles submitted after October 31, 2025 can be registered. (Secret articles can be registered anytime articles are posted.)
When you participate, we will assume that you have agreed to the terms of use
@inetcpl
Literal, Annotated（print卒業）
Overwrite
Title
URL
You can post either your article on Qiita or your blog post.
About reserved posting
If you register a secret article by the day before the same day, it will be automatically published around 7:00 on the same day.
About posting period
Only articles submitted after October 31, 2025 can be registered. (Secret articles can be registered anytime articles are posted.)
When you participate, we will assume that you have agreed to the terms of use
@inetcpl
型情報を外部に公開する（py.typed, typeshed）
Overwrite
Title
URL
You can post either your article on Qiita or your blog post.
About reserved posting
If you register a secret article by the day before the same day, it will be automatically published around 7:00 on the same day.
About posting period
Only articles submitted after October 31, 2025 can be registered. (Secret articles can be registered anytime articles are posted.)
When you participate, we will assume that you have agreed to the terms of use
@inetcpl
コラム回：mypy strict モードを深堀りする
Overwrite
Title
URL
You can post either your article on Qiita or your blog post.
About reserved posting
If you register a secret article by the day before the same day, it will be automatically published around 7:00 on the same day.
About posting period
Only articles submitted after October 31, 2025 can be registered. (Secret articles can be registered anytime articles are posted.)
When you participate, we will assume that you have agreed to the terms of use
@inetcpl
なぜ私たちはPythonで型を書くのか
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Title
URL
You can post either your article on Qiita or your blog post.
About reserved posting
If you register a secret article by the day before the same day, it will be automatically published around 7:00 on the same day.
About posting period
Only articles submitted after October 31, 2025 can be registered. (Secret articles can be registered anytime articles are posted.)
When you participate, we will assume that you have agreed to the terms of use

You can increase the number of series when Calendar 1 is filled with more than 10 articles.

Pythonの型ヒントと共に進化するコード Advent Calendar 2025

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Series 1

How to join the calendar