How to return a variable using another one Python

Question

After working a lot with swift, I got used to the following syntax:

private var __privateVar = 100 // Not accessible from outside the Class
public var public_var: Int = {
    return __privateVar // Returns __privateVar, and is get-only variable
}

Is there a way to reproduce this in python 3? Thanks a lot

[How does the @property decorator work?](https://stackoverflow.com/questions/17330160/how-does-the-property-decorator-work) — Sayse, Feb 18 '20 at 17:33
Still, is there a way to access those variables by returning them from another? — Vipera74, Feb 18 '20 at 17:33
Does Python have “private” variables in classes? https://stackoverflow.com/questions/1641219/does-python-have-private-variables-in-classes — Alexander, Feb 18 '20 at 17:39

osuka_ · Accepted Answer · 2020-02-18T17:45:06.647

Python doesn't even have the concept of access modifiers - so if you mean you want a private variable, that's not something you can do. You can, however, use a read-only property:

class Test:
    def __init__(self):
        self._var = 'some string'

    @property
    def var(self):
        return self._var

Then, use it as such:

obj = Test()
obj.var # works
obj.var = 'whatever' # raises AttributeError
obj._var = 'whatever' # still works

It's noteworthy that you can somewhat emulate the behavior of a private variable by prefixing your variable with a double underscore (such as in __var), which introduces name mangling if used in a class scope. This is not foolproof, though, and you can always get around it if you really want to. Generally, however, Python developers know not to assign to variables starting in one or two underscores.

To be clear, `_var` is _not_ read only and can still be viewed or modified by users. — Alexander, Feb 18 '20 at 17:44
@Alexanderthat should be clear enough from the very first sentence in the answer. — osuka_, Feb 18 '20 at 17:47

How to return a variable using another one Python

1 Answers1