Allow function aliases to be registered for fixing problems, and add some more argument checking for fixing problems

autoload/ale/fix.vim

@@ -191,7 +191,7 @@ function! s:RunFixer(options) abort
     let l:index = a:options.callback_index
 
     while len(a:options.callback_list) > l:index
-        let l:result = function(a:options.callback_list[l:index])(l:buffer, copy(l:input))
+        let l:result = call(a:options.callback_list[l:index], [l:buffer, copy(l:input)])
 
         if type(l:result) == type(0) && l:result == 0
             " When `0` is returned, skip this item.
@@ -223,7 +223,7 @@ function! s:RunFixer(options) abort
     call s:ApplyFixes(l:buffer, l:input)
 endfunction
 
-function! ale#fix#Fix() abort
+function! s:GetCallbacks() abort
     let l:callback_list = []
 
     for l:sub_type in split(&filetype, '\.')
@@ -238,6 +238,40 @@ function! ale#fix#Fix() abort
 
     if empty(l:callback_list)
         echoerr 'No fixers have been defined for filetype: ' . &filetype
+        return []
+    endif
+
+    let l:problem_list = []
+    let l:corrected_list = []
+
+    for l:item in l:callback_list
+        if type(l:item) == type('')
+            if exists('*' . l:item)
+                call add(l:corrected_list, function(l:item))
+            else
+                let l:func = ale#fix#registry#GetFunc(l:item)
+
+                if !empty(l:func) && exists('*' . l:func)
+                    call add(l:corrected_list, function(l:func))
+                else
+                    call add(l:problem_list, l:item)
+                endif
+            endif
+        endif
+    endfor
+
+    if !empty(l:problem_list)
+        echoerr 'Invalid fixers used: ' . string(l:problem_list)
+        return []
+    endif
+
+    return l:corrected_list
+endfunction
+
+function! ale#fix#Fix() abort
+    let l:callback_list = s:GetCallbacks()
+
+    if empty(l:callback_list)
         return
     endif
 

autoload/ale/fix/registry.vim

@@ -0,0 +1,54 @@
+" Author: w0rp <devw0rp@gmail.com>
+" Description: A registry of functions for fixing things.
+
+let s:default_registry = {
+\   'eslint': {
+\       'function': 'ale#handlers#eslint#Fix',
+\       'suggested_filetypes': ['javascript'],
+\       'description': '',
+\   },
+\}
+
+" Reset the function registry to the default entries.
+function! ale#fix#registry#ResetToDefaults() abort
+    let s:entries = deepcopy(s:default_registry)
+endfunction
+
+" Set up entries now.
+call ale#fix#registry#ResetToDefaults()
+
+" Add a function for fixing problems to the registry.
+function! ale#fix#registry#Add(name, func, filetypes, desc) abort
+    if type(a:name) != type('')
+        throw '''name'' must be a String'
+    endif
+
+    if type(a:func) != type('')
+        throw '''func'' must be a String'
+    endif
+
+    if type(a:filetypes) != type([])
+        throw '''filetypes'' must be a List'
+    endif
+
+    for l:type in a:filetypes
+        if type(l:type) != type('')
+            throw 'Each entry of ''filetypes'' must be a String'
+        endif
+    endfor
+
+    if type(a:desc) != type('')
+        throw '''desc'' must be a String'
+    endif
+
+    let s:entries[a:name] = {
+    \   'function': a:func,
+    \   'suggested_filetypes': a:filetypes,
+    \   'description': a:desc,
+    \}
+endfunction
+
+" Get a function from the registry by its short name.
+function! ale#fix#registry#GetFunc(name) abort
+    return get(s:entries, a:name, {'function': ''}).function
+endfunction

test/test_ale_fix.vader

@@ -37,6 +37,7 @@ After:
   delfunction DoNothing
   delfunction CatLine
   delfunction ReplaceWithTempFile
+  call ale#fix#registry#ResetToDefaults()
 
 Given testft (A file with three lines):
   a
@@ -126,3 +127,18 @@ Expect(The first function should be used):
   ^a
   ^b
   ^c
+
+Execute(ALEFix should complain for missing functions):
+  let g:ale_fixers.testft = ['XXX', 'YYY']
+  AssertThrows ALEFix
+  AssertEqual 'Vim(echoerr):Invalid fixers used: [''XXX'', ''YYY'']', g:vader_exception
+
+Execute(ALEFix should use functions from the registry):
+  call ale#fix#registry#Add('add_carets', 'AddCarets', [], 'Add some carets')
+  let g:ale_fixers.testft = ['add_carets']
+  ALEFix
+
+Expect(The registry function should be used):
+  ^a
+  ^b
+  ^c