Add short-circuit boilerplate to plugins

Set a g:loaded_* flag to prevent repeated reloads, and refuse to load at
all if &compatible is set or if required features are missing.

Some more accommodating plugins avoid the problems 'compatible' causes
by saving its value at startup into a script variable, setting the
option to the Vim default, and then restoring it when the plugin is
done, to prevent any of its flags from interfering in the plugin code:

    let s:save_cpo = &cpo
    set cpo&vim
    ...
    let &cpo = s:save_cpo
    unlet s:save_cpo

I don't want this boilerplate, so I'm going to do what Tim Pope's
modules seem to, and just have the plugin refuse to do a single thing if
'compatible' is set.

1 files changed, 44 insertions, 40 deletions

diff --git a/vim/plugin/toggle_option_flag.vim b/vim/plugin/toggle_option_flag.vim
index f83af1cc..ad89d080 100644
--- a/vim/plugin/toggle_option_flag.vim
+++ b/vim/plugin/toggle_option_flag.vim
@@ -7,44 +7,48 @@
 " Author: Tom Ryder <tom@sanctum.geek.nz>
 " License: Same as Vim itself
 "
-if has('eval') && has('user_commands')
-
-  " Internal function to do the toggling
-  function! s:Toggle(option, flag, local)
-
-    " Check for weird options, we don't want to eval() anything funny
-    if a:option =~# '[^a-z]'
-      echoerr 'Illegal option name'
-      return
-    endif
-
-    " Weird flags, too; should be a single inoffensive char
-    if a:flag !~# '^[a-z0-9.]$'
-      echoerr 'Illegal flag'
-      return
-    endif
-
-    " Choose which set command to use
-    let l:set = a:local
-          \ ? 'setlocal'
-          \ : 'set'
-
-    " eval() to assign -= or += to l:op for the option toggle
-    " (I couldn't get {curly braces} indirection to work)
-    let l:op = ''
-    execute 'let l:op = &' . a:option . ' =~# a:flag ? "-=" : "+="'
-
-    " eval() to perform the option toggle and then print the value
-    execute l:set . ' ' . a:option . l:op . a:flag
-    execute l:set . ' ' . a:option . '?'
-
-  endfunction
-
-  " User commands wrapping around calls to the above function
-  command! -nargs=+
-        \ ToggleOptionFlag
-        \ call <SID>Toggle(<f-args>, 0)
-  command! -nargs=+
-        \ ToggleOptionFlagLocal
-        \ call <SID>Toggle(<f-args>, 1)
+if exists('g:loaded_toggle_option_flag')
+      \ || !has('user_commands')
+      \ || &compatible
+  finish
 endif
+let g:loaded_toggle_option_flag = 1
+
+" Internal function to do the toggling
+function! s:Toggle(option, flag, local)
+
+  " Check for weird options, we don't want to eval() anything funny
+  if a:option =~# '[^a-z]'
+    echoerr 'Illegal option name'
+    return
+  endif
+
+  " Weird flags, too; should be a single inoffensive char
+  if a:flag !~# '^[a-z0-9.]$'
+    echoerr 'Illegal flag'
+    return
+  endif
+
+  " Choose which set command to use
+  let l:set = a:local
+        \ ? 'setlocal'
+        \ : 'set'
+
+  " eval() to assign -= or += to l:op for the option toggle
+  " (I couldn't get {curly braces} indirection to work)
+  let l:op = ''
+  execute 'let l:op = &' . a:option . ' =~# a:flag ? "-=" : "+="'
+
+  " eval() to perform the option toggle and then print the value
+  execute l:set . ' ' . a:option . l:op . a:flag
+  execute l:set . ' ' . a:option . '?'
+
+endfunction
+
+" User commands wrapping around calls to the above function
+command! -nargs=+
+      \ ToggleOptionFlag
+      \ call <SID>Toggle(<f-args>, 0)
+command! -nargs=+
+      \ ToggleOptionFlagLocal
+      \ call <SID>Toggle(<f-args>, 1)