Automattic / Automattic/VIP-Coding-Standards

Check the hook callback parameter count ?

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主要言語
PHP
スター
261
フォーク
44
平均マージ
19分
マージ済み PR(30日)
1

説明

## What problem would the enhancement address for VIP?

Prevent potential fatal `ArgumentCount` errors.

## Describe the solution you'd like

Inspired by the `AlwaysReturnInFilter` sniff, I was thinking that once the abstract hook/callback sniff exists, it wouldn't be that hard to create a sniff which would check synchronicity between the parameters requested from a hook-in and the callback function declaration.

This would apply to both `add_filter()` as well as `add_action()`.

Such a sniff would also be a candidate for (eventually moving to) WPCS, but I wanted to discuss the general idea here first, largely to see if the potential issue described above actually occurs in real life situations.

## What code should be reported as a violation?

```php
// Error: Two parameters expected, one (implicit) requested.
add_filter( 'the_title', function( $title, $id ) {
// Do something.
return $title;
} );

// Warning: One parameter expected, two requested.
add_filter( 'the_title', function( $title ) {
// Do something.
return $title;
}, 10, 2 );
```

## What code should *not* be reported as a violation?

```php
// OK: Two parameters expected, two requested.
add_filter( 'the_title', function( $title, $id ) {
// Do something.
return $title;
}, 10, 2 );

// OK: Three parameters expected, two requested, but third parameter is optional,
// which can be done by design to allow direct calls to the function to pass it.
function prefix_title_filter( $title, $id, $optional = null ) {
// Do something.
return $title;
}
add_filter( 'the_title', 'prefix_title_filter', 10, 2 );
```

## Additional context

### Future scope
* Once a list of WP native hooks + the amount of parameters they pass is known (via a trait in WPCS for instance), an additional check could be added that the `$accepted_args` parameter value is never higher than the number of passed parameters when the hook is called.

```php
function prefix_title_filter( $title, $id, $optional = null ) {
// Do something.
return $title;
}

// The `the_title` filter only passes two arguments max, so the code here is an error.
add_filter( 'the_title', 'prefix_title_filter', 10, 3 );
```
* For PHP native functions used in callbacks, reflection could be used to see how many (required) parameters these take and match that with the `$accepted_args` parameter.
* For WP native functions a list based solution would be needed to do the same.

## Relevant links
* https://developer.wordpress.org/reference/functions/add_action/
* https://developer.wordpress.org/reference/functions/add_filter/

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調査の方向性

まず、既存の AlwaysReturnInFilter sniff と、リンクされた WordPress リファレンスに記載されている add_filter() および add_action() のエントリーポイントを確認します。sniff の範囲を定義する前に、オプションのパラメーターやクロージャを含め、コールバック宣言と accepted_args をどのように比較すべきかを明確にします。提供された違反例および非違反例について動作が仕様化されていれば完了です。

索引モデルが issue の本文から書いたものです。

評価

技術スタック
php
領域
tooling
issue の種類
機能追加
難易度
5/5
見積もり時間
1週間以上
活発さ
停滞
明瞭さ
説明が足りない
初心者へのやさしさ
25/100

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