:help :global is an incredibly cool command.
One thing I like to do with :global is to list lines matching a given pattern in the current file and use that to move around. It looks like this:
:g/let/#
7 let &path .= 'src/**,public/**,static/**'
31 unlet b:gqview
33 nmap <silent> GQ :let b:gqview = winsaveview()<CR>:set opfunc=Format<CR>g@
[...]
:
I like it. I use it all the time.
What if there was a way to persist the result of :[range]g/foo/# and use it to move around?
Well, that's what :[range]Global <pattern> does: it simulates :[range]g/<pattern>/# and populates the location list with the result, allowing us to navigate that list with :help :lnext, :help :lprevious, filter it with :help :Lfilter, operate on each line with :help :ldo, etc.
And :[range]Global! <pattern> does the same but for :[range]g!/<pattern>/#/:[range]v/<pattern>/#.
Neat.
List all lines with foo:
:[range]Global foo
List all lines without foo:
:[range]Global! foo
Is there a reason you're avoiding
&grepprgin your example? As opposed to say something similar to your "Instant grep + quickfix" gist e.g.