How to set g:python_indent.disable_parentheses_indenting?

Question

:help ft-python-indent lists the following command:

let g:python_indent.disable_parentheses_indenting = 1

but when I try to use that in my config I am getting the error message

E121: Undefined variable g:python_indent

I am surprised that the variable name contains a dot and judging from the error message it seems like vim indeed considers the dot part the end of the variable name.

I have found the code where the variable is used in /usr/share/vim/vim90/autoload/python.vim:

if g:python_indent.disable_parentheses_indenting == 1

As far as I remember a dot is used to concatenate strings so I thought that maybe these are two variables and I can use either one to enable this feature. So I have tried:

let disable_parentheses_indenting = 1

That does not give an error but does not enable the feature either.

Probably because it's a local variable.

I don't want to set the first variable, g:python_indent because that is used for other features, too, which I don't want to change. But then again it seems pretty clear in the help that this is supposed to be a single variable.

What is going on here?

How can I enable this feature?

I am using vim 9.0.

Answer 1

The . syntax is an alternative to access a dictionary value associated to a key.

let g:python_indent.disable_parentheses_indenting = 1

Is equivalent to:

let g:python_indent['disable_parentheses_indenting'] = 1

To define it you first declare g:python_indent as a dictionary

let g:python_indent = {}
let g:python_indent.disable_parentheses_indenting = 1

Or if you want to be sure not to empty an existing dictionary

if !exists('g:python_indent')
  let g:python_indent = {}
endif
let g:python_indent.disable_parentheses_indenting = 1