Id' Is a Bad Variable Name in Python

id' is a bad variable name in Python

id() is a fundamental built-in:

Help on built-in function id in module
__builtin__:

id(...)

    id(object) -> integer

    Return the identity of an object.  This is guaranteed to be unique among
    simultaneously existing objects.  (Hint: it's the object's memory
    address.)

In general, using variable names that eclipse a keyword or built-in function in any language is a bad idea, even if it is allowed.

Is `id` a keyword in python?

id is not a keyword in Python, but it is the name of a built-in function.

The keywords are:

and       del       from      not       while
as        elif      global    or        with
assert    else      if        pass      yield
break     except    import    print
class     exec      in        raise
continue  finally   is        return
def       for       lambda    try

Keywords are invalid variable names. The following would be a syntax error:

if = 1

On the other hand, built-in functions like id or type or str can be shadowed:

str = "hello"    # don't do this

Is it a bad practice to name a instance variable after a built-in

I would say it's ok.

Grepping through Python's standard library you can see plenty of places where attributes are named the same as built-ins:

For example:

:~/cpython/Lib$ egrep -R "\.set[^a-zA-Z0-9_]" | wc -l
583
:~/cpython/Lib$ egrep -R "\.type[^a-zA-Z0-9_]" | wc -l
319

Is it bad practice to use a built-in function name as an attribute or method identifier?

It won't confuse the interpreter but it may confuse people reading your code. Unnecessary use of builtin names for attributes and methods should be avoided.

Another ill-effect is that shadowing builtins confuses syntax highlighters in most python-aware editors (vi, emacs, pydev, idle, etc.) Also, some of the lint tools will warn about this practice.

ID, id, or Id?

I do what I feel like. In general, your best practice is to err in favor of readability vs. compliance with some abstract standard.

Just be consistent.

Is giving an argument the same name as the kwarg parameter bad practice in Python?

It's unlikely to be considered bad practice, given that it is used more often than not in the major python packages; see e.g. a random pandas example here (takes a while to jump to the right line).

As for readability I would instead consider it beneficial to have identical names in both scopes whenever you are referring to the same thing. If appropriate, you can still use more specific names to refer to more specific concepts outside the function, such as the production environment file (e.g. dotenv_prod_path = r"./../.env.prod"; load_dotenv(dotenv_path=dotenv_prod_path)).

If you are concerned about reduced readability as it might be unclear which scope the name belongs to, I would suggest to keep methods/functions short and not to use global and nonlocal variables.

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