In h: internal-variables it mentions the "global" variable which is prefixed by g:. What would be the difference between:

let g:var = "xyz"


let var = "xyz"

Does the absence of a prefix mean g:, or are they two different things?

  • Depends on context: the scope default to different things depending on where its used (script local in scripts, function local in functions, i think. Plus there are buffer and window local, which are never defaults) – D. Ben Knoble Jun 13 '20 at 3:41

In VimScript all variables have a scope. Or, better to say, they are organized into :h Dictionaries with reserved names. So echo g: is a perfectly valid command.

There are the following scopes (dictionaries) in no particular order:

  1. g: Global
  2. s: Script-local (like "static" in C)
  3. l: Function-local
  4. a: Function argument
  5. v: Vim internal
  6. b: Buffer local
  7. w: Window local
  8. t: Tab local

If scope is not given then v: is searched. If there's no such variable in v: then it's either s: or l: depending on the execution context. Also, while on the command line it's g:, as, obviously, neither s: nor l: applies in interactive mode.

  • thanks, so if I execute :let var = "new" then that goes into the g: dict because I haven't qualified its prefix/namespace? – David542 Jun 13 '20 at 6:40
  • 1
    Interactively? Yes. You can always check it with echo g:var or echo get(g:, 'var') – Matt Jun 13 '20 at 6:43
  • I did not know for nothing that could be interpreted as s:... oO BTW, there is also a little issue with lambdas: we have to be explicit to use global variables, even interactively, while it's not the case in echo map(somelist, 'v:val > globalthreshold'). – Luc Hermitte Jun 13 '20 at 13:29
  • @LucHermitte Lambda is a kind of closure, so it's normal when it inherits default meaning of l:, a: and s: as if executing in the outer scope. However, it's really strange that "global" lambda does not have g: by default. Should it be called inconsistency or bug? – Matt Jun 13 '20 at 14:20
  • @Matt, I'd say inconsistency. – Luc Hermitte Jun 13 '20 at 16:01

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