Merge pull request #532 from dbarnett/per_buffer

Add support for buffer-local b:syntastic_checkers var.

doc/syntastic.txt

@@ -299,6 +299,12 @@ e.g. >
     let g:syntastic_python_checkers = ['flake8']
 <
 
+There's also a per-buffer version of this setting, b:syntastic_checkers. Use
+this in an autocmd to configure specific checkers for particular paths: >
+    autocmd FileType python if stridx(expand('%:p'), '/some/path/') == 0 |
+        \ let b:syntastic_checkers = ['pylint'] | endif
+<
+
 To see the list of available checkers for your filetype, look in
 `syntax_checkers/<filetype>/`. The names of the files here correspond to
 '<checker-name>' above.

plugin/syntastic/registry.vim

@@ -110,7 +110,11 @@ function! g:SyntasticRegistry._filterCheckersByDefaultSettings(checkers, filetyp
 endfunction
 
 function! g:SyntasticRegistry._filterCheckersByUserSettings(checkers, filetype)
-    let whitelist = g:syntastic_{a:filetype}_checkers
+    if exists("b:syntastic_checkers")
+        let whitelist = b:syntastic_checkers
+    else
+        let whitelist = g:syntastic_{a:filetype}_checkers
+    endif
     return filter(a:checkers, "index(whitelist, v:val.name()) != -1")
 endfunction
 
@@ -135,7 +139,7 @@ function! g:SyntasticRegistry._haveLoadedCheckers(filetype)
 endfunction
 
 function! g:SyntasticRegistry._userHasFiletypeSettings(filetype)
-    return exists("g:syntastic_" . a:filetype . "_checkers")
+    return exists("b:syntastic_checkers") || exists("g:syntastic_" . a:filetype . "_checkers")
 endfunction
 
 function! g:SyntasticRegistry._validateUniqueName(checker) abort