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EX.Subclass relationships
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README.md
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README.md
@ -47,7 +47,7 @@ So, here we go...
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- [> The disappearing variable from outer scope/消失的外部变量](#-the-disappearing-variable-from-outer-scope消失的外部变量)
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- [> When True is actually False/真亦假](#-when-true-is-actually-false真亦假)
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- [> From filled to None in one instruction.../从有到无...](#-from-filled-to-none-in-one-instruction从有到无)
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- [> Subclass relationships *](#-subclass-relationships-)
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- [> Subclass relationships/子类关系 *](#-subclass-relationships子类关系-)
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- [> The mysterious key type conversion *](#-the-mysterious-key-type-conversion-)
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- [> Let's see if you can guess this?](#-lets-see-if-you-can-guess-this)
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- [Section: Appearances are deceptive!](#section-appearances-are-deceptive)
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@ -1096,7 +1096,7 @@ None
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---
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### > Subclass relationships *
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### > Subclass relationships/子类关系 *
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**Output:**
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```py
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@ -1109,14 +1109,14 @@ True
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False
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```
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The Subclass relationships were expected to be transitive, right? (i.e., if `A` is a subclass of `B`, and `B` is a subclass of `C`, the `A` _should_ a subclass of `C`)
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子类关系应该是可传递的, 对吧? (即, 如果 `A` 是 `B` 的子类, `B` 是 `C` 的子类, 那么 `A` _应该_ 是 `C` 的子类.)
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#### 💡 Explanation:
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#### 💡 说明:
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* Subclass relationships are not necessarily transitive in Python. Anyone is allowed to define their own, arbitrary `__subclasscheck__` in a metaclass.
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* When `issubclass(cls, Hashable)` is called, it simply looks for non-Falsey "`__hash__`" method in `cls` or anything it inherits from.
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* Since `object` is hashable, but `list` is non-hashable, it breaks the transitivity relation.
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* More detailed explanation can be found [here](https://www.naftaliharris.com/blog/python-subclass-intransitivity/).
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* Python 中的子类关系并不一定是传递的. 任何人都可以在元类中随意定义 `__subclasscheck__`.
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* 当 `issubclass(cls, Hashable)` 被调用时, 它只是在 `cls` 中寻找 `__hash__` 方法或者从继承的父类中寻找 `__hash__` 方法.
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* 由于 `object` is 可散列的(hashable), 但是 `list` 是不可散列的, 所以它打破了这种传递关系.
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* 在[这里](https://www.naftaliharris.com/blog/python-subclass-intransitivity/)可以找到更详细的解释.
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---
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