Question

Is it possible to get a list of declared variables with a VimL (aka VimScript) expression? I’d like to get the same set of values that will be presented for a command using -complete=expression. The goal is to augment that list for use in a user-defined command completion function.

Answer 1

You can use g: as a dictionary that holds all global variables, so:

let globals = keys(g:)

will give you all the names. The same applies to the other scopes: b:, s:, w:, etc. See :help internal-variables for the complete list.