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by _ZeD_
4861 days ago
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In java the arrays objects expose a public int attribute called .length.
The strings also expose a .length attribute, but it's a method.
If, for some reason, you need to know how many elements are in enum, you need to call NameOfTheEnum.values().length.
If you have a Collection (a Map, a List...), you need to call .size().
... Yeah. You are right about the fact that a possible "convention" would be to call .len, not .__len__ but you are forgetting 20+ years of backward compatibility. I don't know when len() was introduced, and I'm not sure it's initial implementation was a simple "return object.__len__()" (or an equivalent...).
What I know is that an explicit len function helped to hide the eventually different implementation details, and allowed the developers of the containers go crazy with attributes. Moreover, with a len(obj) function and a obj.len() "public" method, you have two ways to do it. |
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