How often have you used the function
range() in Python? It’s often something you use early on as you learn about the
But… did you know it’s not really a function, after all?!
Have a look at the docs or use
help() to check…
range is a class. And therefore
range() creates an instance of the class as is always the case with a class.
So, my question is: “Does it matter?”
Technically, it does. A function is not a class – they’re different things
But in practice, what matters is how it behaves and not what it is!
This is a key principle in Python when thinking about data types. What they do and how they behave matters more that what they are!
So you can use
range() like a function, even though it’s not!
@s_gruppetta surely, range() *is* a function - a constructor - which _returns_ an instance of a class? I guess the clever bit is that the class acts a bit like an iterator... (though why it's /not/ an iterator is a puzzle to me)
@raymondlesley one could argue the functions are the __new__() and __init__() methods, as with any class, and not the class itself. But the class is callable, like a function, of course
And the capital letter is just a convention, after all. I believe this is deliberate as the intention is that it’s used “like a function”, even though it isn’t. This comes from Python’s duck-typing philosophy.
@s_gruppetta Interesting. I'm going to have to go back to my Python book and see what it says about this. I'm fairly sure it just presents it as a command to be used in a certain way.
@s_gruppetta Thanks for sharing! I think this is what APIs of any kind are for - serve the purpose and be easy to understand: no matter if that's a built-in library, some additional package or even REST/SOAP. Clearly, a good example that we should focus on building a good interfaces first.
@s_gruppetta Is this really so different to other languages. The instance created by range() is simply enumerable (including iterators). This concept exists in lot of languages.
@CodingKurzgeschichten I wasn’t claiming in any way this is unique to Python. The point is that we use range as function – and that’s the way it was intended – but it’s not. It’s a class
@CodingKurzgeschichten This fits well within the concept of duck-typing which is true for some language but not others.
What matters here is not what it is but how it behaves, and this is a broader mindset in languages such as Python
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