Why does vimscript use `set cpo&vim`?

Question

Please explain following two lines found in synload.vim file:

let s:cpo_save = &cpo
set cpo&vim

What is vim in the last expression? What is result of such an expression, and what does it affect?

Note you can find the help page for this with :h &vim, which will find the help page Matt mentioned; just FYI for the next time you're confused by something in Vim: just try entering stuff in :help and see what comes up :-) Using :help something<Tab> to get the autocomplete list is also very useful. — Martin Tournoij, Mar 25 '20 at 22:32
Does this answer your question? Is cpo&vim a special syntax? — Martin Tournoij, Mar 25 '20 at 22:34
While, I totally agree with you all, the help page doesn't explain why the plugins have this habit. — Luc Hermitte, Mar 26 '20 at 12:25
l00p, I've edited your question to make it less of a dupe (and more relevant to @LucHermitte 's answer). If you feel the edits go against the grain of the question you were asking, feel free to revert them. But I feel the question stands better on it's own this way — D. Ben Knoble, Mar 26 '20 at 14:42
Fair enough @LucHermitte; I've retracted the duplicate vote. — Martin Tournoij, Mar 27 '20 at 02:57

Luc Hermitte · Accepted Answer · 2020-03-25T14:34:58.407

6

It resets 'cpo' value to its default value.

Some people may be running vim in compatible mode, by choice or not. In those cases, various things would be inhibited, things we usually rely upon when writing plugins -- in particular :h line-continuation. As a consequence, the plugins would emit many error messages.

Resetting 'cpo' to its factory setting, the plugin becomes resilient to these hostile (IMO) configurations.

This syntax could be used with many (all?) vim options. Before doing that, we record the old value in order to properly restore it afterward

let s:cpo_save = &cpo
set cpo&vim
.
. plugin code
.
let &cpo = s:cpo_save

edited Mar 25 '20 at 14:34

answered Mar 25 '20 at 00:21

Luc Hermitte

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@BLayer Indeed. thanks :) – Luc Hermitte Mar 25 '20 at 01:16
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No problemo :) ... – B Layer Mar 25 '20 at 03:01

Why does vimscript use `set cpo&vim`?

1 Answers1