Add `dir` option: managed plugins outside `g:plug_home`

README.md

@@ -76,6 +76,7 @@ Reload .vimrc and `:PlugInstall` to install plugins.
 | -------------- | -------------------------------------------------------------------- |
 | `branch`/`tag` | Branch or tag of the repository to use                               |
 | `rtp`          | Subdirectory that contains Vim plugin                                |
+| `dir`          | Custom directory for the plugin                                      |
 | `do`           | Post-update hook (string or funcref)                                 |
 | `on`           | On-demand loading: Commands or `<Plug>`-mappings                     |
 | `for`          | On-demand loading: File types                                        |

plug.vim

@@ -319,8 +319,8 @@ function! s:add(force, repo, ...)
       return
     endif
 
-    let spec = extend(a:0 == 1 ? s:parse_options(a:1) : copy(s:base_spec),
-                    \ s:infer_properties(name, repo))
+    let spec = extend(s:infer_properties(name, repo),
+                    \ a:0 == 1 ? s:parse_options(a:1) : copy(s:base_spec))
     if !a:force
       let s:extended[name] = spec
     endif
@@ -342,6 +342,9 @@ function! s:parse_options(arg)
     if has_key(opts, 'tag')
       let opts.branch = remove(opts, 'tag')
     endif
+    if has_key(opts, 'dir')
+      let opts.dir = s:dirpath(expand(opts.dir))
+    endif
   else
     throw 'Invalid argument type (expected: string or dictionary)'
   endif

test/workflow.vader

@@ -660,6 +660,27 @@ Execute (Using Funcref):
   Assert filereadable(g:plugs['vim-pseudocl'].dir.'/vim-pseudoclinstalled2'),
     \ 'vim-pseudocl/vim-pseudoclinstalled2 should exist'
 
+
+**********************************************************************
+~ Overriding `dir`
+**********************************************************************
+
+Execute (Using custom dir):
+  Assert isdirectory(g:plugs['vim-easy-align'].dir)
+
+  call plug#begin()
+  Plug 'junegunn/vim-easy-align', { 'dir': $TMPDIR.'easy-align' }
+  call plug#end()
+  AssertEqual $TMPDIR.'easy-align/', g:plugs['vim-easy-align'].dir
+
+  PlugClean!
+  Assert !isdirectory(g:plugs['vim-easy-align'].dir)
+  q
+
+  PlugInstall
+  q
+  Assert isdirectory(g:plugs['vim-easy-align'].dir)
+
 Execute (Cleanup):
   call system('rm -rf '.temp_plugged)
   call rename('fzf', 'fzf-staged')