Comment by crazygringo | Hacker News Reader

Comment by crazygringo | Hacker News Reader

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> There's no type casting in Python.

If you search "type casting in Python" you will find lots of articles explaining how to use int(), str(), etc. to cast. This is a common and well-documented concept, even if it's different under the hood from e.g. C.

The idea that you'd name a function bool() and have it act differently is a deeply confusing design decision that it's understandable people would get misled by and frustrated with. This is a function named after a fundamental type. It's not a random user-defined constructor.

If we do it that way, we have worse problems.

    if "False":  
       # What do you expect?  True or False?  
       print("True")
    else:
       print("False")

bool() is consistent with how "truthiness" happens in python. Otherwise we end up with the YAML norway problem.

    if bool("False"):
       print("True")
    else:
       print("False")  # This would be different if we landed here.

And that would be different behavior then the above -- creating a nasty inconsistency.

Honestly it's not that hard to write something that looks like this:

    def str_to_bool(val: str) -> bool:
        return val.lower() in ["yes", "true", "1"]

bool() is not a function named after a fundamental type. bool is a type. As with any type, you can call bool(...) to construct a new object of that type.

https://docs.python.org/3/library/functions.html#bool

A good tutorial will reflect this fact and use appropriate language.

Both the idea that you can "cast", and the idea that bool is a function, are misunderstandings rooted in the idea that Python should be like C in all ways.

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