How to disable Ale if PAGER mode is enabled

Question

I use both Ale and VIM pager plugins. But for obvious reasons I want to disable some Vim features and plugins in the "less" mode.

But if I put as recommended this piece of code in my .vimrc it still starts Ale:

if exists('g:vimpager.enabled')
   set nospell
   let g:ale_enabled = 0
endif

And if I start vimpager with vimpager some_file.py it will still show Ale error and warning messages

Answer 1

To quote the docs:

To disable loading plugins, put "set noloadplugins" into a vimpagerrc file.

Vimpagerrc can be ~/.vimpagerrc or (recommended for version control) ~/.vim/vimpagerrc or in the file named by the value of the environment variable VIMPAGER_RC

You could also try putting

let g:ale_enabled = 0

in the vimpagerrc as filbranden suggests.

Answer 2

The answer was in the vimpager initialization. Before it was stated that initialization of the plugin should be done by adding these lines in the .vimrc:

let g:vimpager = {}
let g:less = {}
let g:vimpager.passthrough = 0

But and the check for the g:vimpager.enabled occured later in the VIMRC file. Obviously the value of g:vimpager was reset by this point, rendering the check useless. So the right way would be to write :

if !exists('g:vimpager')
    let g:vimpager = {}
endif
if !exists('g:less')
    let g:less = {}
endif
let g:vimpager.passthrough = 0
...
if !exists('g:vimpager.enabled')
    Plug 'dense-analysis/ale'
endif

Note the disabling the inclusion of the Ale plugin completely - it speeds up the loading considerably, compared to just setting let g:ale_enabled = 0. The documentation for vimpager plugin was fixed in e887ecc commit.