refactor: separate the child creation and initialization (#81)

- includes modified class implementation from https://github.com/rxi/classic/blob/master/classic.lua
- now base component class is created from classic.
- change to how component classes are created.
  - Don't overwrite new method to initialize a component.
    Overwrite the init method. new is responsible for
    creating class object and calling init on it.
    Unlike previous new overwrite you don't need to create
    the class (table) and return it. Instead you will recive
    the object as self and do required manipulation on that
    just like any most other oop langs. Also don't need to
    return anything from init. init's job is to initialize.
    remember to call classes init before running your operations
    unfortunately lua isn't full fledged oop lang and I don't
    how to automate this.
- changes how super classes are accesed.
  - rename Component._parent -> Component.super
  - methods on super classes now ran through super class instead
    of objects _parent self._parent as that can lead to recursive inf loop.
  See branch, diff, tabs, buffer classes call to init for example
  on pattern.
- All components updated to reflect current logic
- component loader updated to use new initialization procedure.
- updated tests
- updated BREAKING_CHANGES.md
- plus quite a bit of formatting changes in the components
  - comp.method = function(self, ...) -> function M:method(...)
BREAKING_CHANGE

BREAKING_CHANGES.md

@@ -61,3 +61,33 @@ See [#24](https://github.com/shadmansaleh/lualine.nvim/pull/24) for details
 modified, removed in diff_color table option
 - color_error, color_warning, color_info, color_hint are now available
 as error, warn, info, hint in diagnostics_color table option
+
+### Component class refactor
+***Applicable only ones responsible for custom components***
+- Now call extend method on super class to create new type of component instead of calling new with empty args.
+- Don't overrite new method for initialization. Overrite init instead.
+- rename Component._parent -> Component.super
+- Call methods from super class directly on classes super not through
+  objects super or self.super
+So basically if you had something like
+```lua
+local my_comp = require'lualine.component':new()
+function mycomp:new(options, child)
+  local obj = self._parent:new(options, child or my_comp)
+  obj.x = 1
+  obj.y = 2
+  return obj
+end
+```
+change it to
+```lua
+local my_comp = require('lualine.component'):extend()
+
+function my_comp:init(options)
+  -- Notice carefully it's not self.super.init nor my_comp.super:init
+  my_comp.super.init(self, options)
+  self.x = 1
+  self.y = 2
+end
+```
+

lua/lualine/component.lua

@@ -1,6 +1,8 @@
 -- Copyright (c) 2020-2021 shadmansaleh
 -- MIT license, see LICENSE for more details.
+local require = require('lualine_require').require
 local highlight = require 'lualine.highlight'
+local M = require('lualine.utils.class'):extend()
 
 -- Used to provide a unique id for each component
 local component_no = 1
@@ -27,28 +29,29 @@ for %s component.
   rename_notice('format', 'fmt')
   rename_notice('condition', 'cond')
 end
-local Component = {
-  -- Creates a new component
-  new = function(self, options, child)
-    local new_component = {}
-    new_component.options = options
-    new_component._parent = child or self
-    setmetatable(new_component, { __index = new_component._parent })
-    -- Operation that are required for creating new components but not for inheritence
-    if options ~= nil then
-      component_no = component_no + 1
-      check_deprecated_options(new_component.options)
-      if not options.component_name then
-        new_component.options.component_name = tostring(component_no)
-      end
-      new_component.component_no = component_no
-      new_component:set_separator()
-      new_component:create_option_highlights()
-    end
-    return new_component
-  end,
 
-  set_separator = function(self)
+function M:__tostring()
+  local str = 'Component: ' .. self.options.component_name
+  if self.debug then
+    str = str .. '\n---------------------\n' .. vim.inspect(self)
+  end
+  return str
+end
+
+-- Initialize new component
+function M:init(options)
+  self.options = options or {}
+  component_no = component_no + 1
+  check_deprecated_options(self.options)
+  if not options.component_name then
+    self.options.component_name = tostring(component_no)
+  end
+  self.component_no = component_no
+  self:set_separator()
+  self:create_option_highlights()
+end
+
+function M:set_separator()
   if self.options.separator == nil then
     if self.options.component_separators then
       if self.options.self.section < 'lualine_x' then
@@ -58,9 +61,9 @@ local Component = {
       end
     end
   end
-  end,
+end
 
-  create_option_highlights = function(self)
+function M:create_option_highlights()
   -- set custom highlights
   if self.options.color then
     self.options.color_highlight = highlight.create_component_highlight_group(
@@ -69,10 +72,10 @@ local Component = {
       self.options
     )
   end
-  end,
+end
 
-  -- set upper or lower case
+-- set upper or lower case
-  apply_case = function(self)
+function M:apply_case()
   -- Donn't work on components that emit vim statusline escaped chars
   if self.status:find '%%' and not self.status:find '%%%%' then
     return
@@ -82,10 +85,10 @@ local Component = {
   elseif self.options.lower == true then
     self.status = self.status:lower()
   end
-  end,
+end
 
-  -- Adds spaces to left and right of a component
+-- Adds spaces to left and right of a component
-  apply_padding = function(self)
+function M:apply_padding()
   local padding = self.options.padding
   local l_padding, r_padding
   if padding == nil then
@@ -109,10 +112,10 @@ local Component = {
   if r_padding then
     self.status = self.status .. string.rep(' ', r_padding)
   end
-  end,
+end
 
-  -- Applies custom highlights for component
+-- Applies custom highlights for component
-  apply_highlights = function(self, default_highlight)
+function M:apply_highlights(default_highlight)
   if self.options.color_highlight then
     self.status = highlight.component_format_highlight(self.options.color_highlight) .. self.status
   end
@@ -129,18 +132,18 @@ local Component = {
   if not self.status:find '^%%#' then
     self.status = default_highlight .. self.status
   end
-  end,
+end
 
-  -- Apply icon in front of component
+-- Apply icon in front of component
-  apply_icon = function(self)
+function M:apply_icon()
   if self.options.icons_enabled and self.options.icon then
     self.status = self.options.icon .. ' ' .. self.status
   end
-  end,
+end
 
-  -- Apply separator at end of component only when
+-- Apply separator at end of component only when
-  -- custom highlights haven't affected background
+-- custom highlights haven't affected background
-  apply_separator = function(self)
+function M:apply_separator()
   local separator = self.options.separator
   if type(separator) == 'table' then
     if self.options.separator[2] == '' then
@@ -157,9 +160,9 @@ local Component = {
     self.status = self.status .. separator
     self.applied_separator = self.applied_separator .. separator
   end
-  end,
+end
 
-  apply_section_separators = function(self)
+function M:apply_section_separators()
   if type(self.options.separator) ~= 'table' then
     return
   end
@@ -170,26 +173,26 @@ local Component = {
   if self.options.separator.right ~= nil and self.options.separator.right ~= '' then
     self.status = string.format('%s%%S{%s}', self.status, self.options.separator.right)
   end
-  end,
+end
 
-  strip_separator = function(self)
+function M:strip_separator()
   if not self.applied_separator then
     self.applied_separator = ''
   end
   self.status = self.status:sub(1, (#self.status - #self.applied_separator))
   self.applied_separator = nil
   return self.status
-  end,
+end
 
-  -- variable to store component output for manipulation
+-- variable to store component output for manipulation
-  status = '',
+M.status = ''
-  -- Actual function that updates a component. Must be overwritten with component functionality
+-- Actual function that updates a component. Must be overwritten with component functionality
-  -- luacheck: push no unused args
+-- luacheck: push no unused args
-  update_status = function(self, is_focused) end,
+function M:update_status(is_focused) end
-  -- luacheck: pop
+-- luacheck: pop
 
-  -- Driver code of the class
+-- Driver code of the class
-  draw = function(self, default_highlight, is_focused)
+function M:draw(default_highlight, is_focused)
   self.status = ''
   self.applied_separator = ''
 
@@ -210,7 +213,6 @@ local Component = {
     self:apply_separator()
   end
   return self.status
-  end,
+end
-}
 
-return Component
+return M

lua/lualine/components/branch.lua

@@ -1,49 +1,48 @@
 -- Copyright (c) 2020-2021 shadmansaleh
 -- MIT license, see LICENSE for more details.
-local Branch = require('lualine.component'):new()
+local M = require('lualine.component'):extend()
 local modules = require('lualine_require').lazy_require {
   utils = 'lualine.utils.utils',
 }
 -- vars
-Branch.git_branch = ''
+M.git_branch = ''
-Branch.git_dir = ''
+M.git_dir = ''
 -- os specific path separator
-Branch.sep = package.config:sub(1, 1)
+M.sep = package.config:sub(1, 1)
 -- event watcher to watch head file
 -- Use file wstch for non windows and poll for windows.
 -- windows doesn't like file watch for some reason.
-Branch.file_changed = Branch.sep ~= '\\' and vim.loop.new_fs_event() or vim.loop.new_fs_poll()
+M.file_changed = M.sep ~= '\\' and vim.loop.new_fs_event() or vim.loop.new_fs_poll()
-Branch.active_bufnr = '0'
+M.active_bufnr = '0'
 local branch_cache = {} -- stores last known branch for a buffer
 -- Initilizer
-Branch.new = function(self, options, child)
+M.init = function(self, options)
-  local new_branch = self._parent:new(options, child or Branch)
+  M.super.init(self, options)
-  if not new_branch.options.icon then
+  if not self.options.icon then
-    new_branch.options.icon = '' -- e0a0
+    self.options.icon = '' -- e0a0
   end
   -- run watch head on load so branch is present when component is loaded
-  Branch.find_git_dir()
+  M.find_git_dir()
   -- update branch state of BufEnter as different Buffer may be on different repos
   modules.utils.define_autocmd('BufEnter', "lua require'lualine.components.branch'.find_git_dir()")
-  return new_branch
 end
 
-Branch.update_status = function(_, is_focused)
+M.update_status = function(_, is_focused)
-  if Branch.active_bufnr ~= vim.g.actual_curbuf then
+  if M.active_bufnr ~= vim.g.actual_curbuf then
     -- Workaround for https://github.com/hoob3rt/lualine.nvim/issues/286
     -- See upstream issue https://github.com/neovim/neovim/issues/15300
     -- Diff is out of sync re sync it.
-    Branch.find_git_dir()
+    M.find_git_dir()
   end
   if not is_focused then
     return branch_cache[vim.fn.bufnr()] or ''
   end
-  return Branch.git_branch
+  return M.git_branch
 end
 
 local git_dir_cache = {} -- Stores git paths that we already know of
 -- returns full path to git directory for current directory
-function Branch.find_git_dir()
+function M.find_git_dir()
   -- get file dir so we can search from that dir
   local file_dir = vim.fn.expand '%:p:h'
   local root_dir = file_dir
@@ -54,7 +53,7 @@ function Branch.find_git_dir()
       git_dir = git_dir_cache[root_dir]
       break
     end
-    local git_path = root_dir .. Branch.sep .. '.git'
+    local git_path = root_dir .. M.sep .. '.git'
     local git_file_stat = vim.loop.fs_stat(git_path)
     if git_file_stat then
       if git_file_stat.type == 'directory' then
@@ -66,12 +65,12 @@ function Branch.find_git_dir()
         git_dir = git_dir:match 'gitdir: (.+)$'
         file:close()
         -- submodule / relative file path
-        if git_dir and git_dir:sub(1, 1) ~= Branch.sep and not git_dir:match '^%a:.*$' then
+        if git_dir and git_dir:sub(1, 1) ~= M.sep and not git_dir:match '^%a:.*$' then
           git_dir = git_path:match '(.*).git' .. git_dir
         end
       end
       if git_dir then
-        local head_file_stat = vim.loop.fs_stat(git_dir .. Branch.sep .. 'HEAD')
+        local head_file_stat = vim.loop.fs_stat(git_dir .. M.sep .. 'HEAD')
         if head_file_stat and head_file_stat.type == 'file' then
           break
         else
@@ -79,54 +78,54 @@ function Branch.find_git_dir()
         end
       end
     end
-    root_dir = root_dir:match('(.*)' .. Branch.sep .. '.-')
+    root_dir = root_dir:match('(.*)' .. M.sep .. '.-')
   end
 
   git_dir_cache[file_dir] = git_dir
-  if Branch.git_dir ~= git_dir then
+  if M.git_dir ~= git_dir then
-    Branch.git_dir = git_dir
+    M.git_dir = git_dir
-    Branch.update_branch()
+    M.update_branch()
   end
   return git_dir
 end
 
 -- sets git_branch veriable to branch name or commit hash if not on branch
-function Branch.get_git_head(head_file)
+function M.get_git_head(head_file)
   local f_head = io.open(head_file)
   if f_head then
     local HEAD = f_head:read()
     f_head:close()
     local branch = HEAD:match 'ref: refs/heads/(.+)$'
     if branch then
-      Branch.git_branch = branch
+      M.git_branch = branch
     else
-      Branch.git_branch = HEAD:sub(1, 6)
+      M.git_branch = HEAD:sub(1, 6)
     end
   end
   return nil
 end
 
 -- Update branch
-function Branch.update_branch()
+function M.update_branch()
-  Branch.active_bufnr = tostring(vim.fn.bufnr())
+  M.active_bufnr = tostring(vim.fn.bufnr())
-  Branch.file_changed:stop()
+  M.file_changed:stop()
-  local git_dir = Branch.git_dir
+  local git_dir = M.git_dir
   if git_dir and #git_dir > 0 then
-    local head_file = git_dir .. Branch.sep .. 'HEAD'
+    local head_file = git_dir .. M.sep .. 'HEAD'
-    Branch.get_git_head(head_file)
+    M.get_git_head(head_file)
-    Branch.file_changed:start(
+    M.file_changed:start(
       head_file,
-      Branch.sep ~= '\\' and {} or 1000,
+      M.sep ~= '\\' and {} or 1000,
       vim.schedule_wrap(function()
         -- reset file-watch
-        Branch.update_branch()
+        M.update_branch()
       end)
     )
   else
     -- set to '' when git dir was not found
-    Branch.git_branch = ''
+    M.git_branch = ''
   end
-  branch_cache[vim.fn.bufnr()] = Branch.git_branch
+  branch_cache[vim.fn.bufnr()] = M.git_branch
 end
 
-return Branch
+return M

lua/lualine/components/buffers.lua

@@ -1,6 +1,6 @@
 -- Copyright (c) 2020-2021 shadmansaleh
 -- MIT license, see LICENSE for more details.
-local Buffers = require('lualine.component'):new()
+local M = require('lualine.component'):extend()
 local highlight = require 'lualine.highlight'
 
 local default_options = {
@@ -134,29 +134,28 @@ function Buffer:name()
     or vim.fn.pathshorten(vim.fn.fnamemodify(self.file, ':p:.'))
 end
 
-function Buffers:new(options, child)
+function M:init(options)
-  local newObj = self._parent:new(options, child or Buffers)
+  M.super.init(self, options)
   default_options.buffers_color = {
     active = get_hl(options.self.section, true),
     inactive = get_hl(options.self.section, false),
   }
-  newObj.options = vim.tbl_deep_extend('keep', newObj.options or {}, default_options)
+  self.options = vim.tbl_deep_extend('keep', self.options or {}, default_options)
-  newObj.highlights = {
+  self.highlights = {
     active = highlight.create_component_highlight_group(
-      newObj.options.buffers_color.active,
+      self.options.buffers_color.active,
       'buffers_active',
-      newObj.options
+      self.options
     ),
     inactive = highlight.create_component_highlight_group(
-      newObj.options.buffers_color.inactive,
+      self.options.buffers_color.inactive,
       'buffers_active',
-      newObj.options
+      self.options
     ),
   }
-  return newObj
 end
 
-function Buffers:update_status()
+function M:update_status()
   local data = {}
   local buffers = {}
   for b = 1, vim.fn.bufnr '$' do
@@ -267,4 +266,4 @@ vim.cmd [[
   endfunction
 ]]
 
-return Buffers
+return M

lua/lualine/components/diagnostics.lua

@@ -7,7 +7,7 @@ local modules = lualine_require.lazy_require {
   utils_notices = 'lualine.utils.notices',
 }
 
-local Diagnostics = lualine_require.require('lualine.component'):new()
+local M = lualine_require.require 'lualine.component':extend()
 
 local function check_deprecated_options(options)
   if options.color_error or options.color_warn or options.color_info or options.color_hint then
@@ -83,56 +83,55 @@ local default_options = {
   },
 }
 -- Initializer
-Diagnostics.new = function(self, options, child)
+function M:init(options)
   -- Run super()
-  local new_diagnostics = self._parent:new(options, child or Diagnostics)
+  M.super.init(self, options)
   -- Apply default options
-  new_diagnostics.options = vim.tbl_deep_extend('keep', new_diagnostics.options or {}, default_options)
+  self.options = vim.tbl_deep_extend('keep', self.options or {}, default_options)
-  check_deprecated_options(new_diagnostics.options)
+  check_deprecated_options(self.options)
   -- Apply default symbols
-  new_diagnostics.symbols = vim.tbl_extend(
+  self.symbols = vim.tbl_extend(
     'keep',
-    new_diagnostics.options.symbols or {},
+    self.options.symbols or {},
-    new_diagnostics.options.icons_enabled ~= false and default_symbols.icons or default_symbols.no_icons
+    self.options.icons_enabled ~= false and default_symbols.icons or default_symbols.no_icons
   )
   -- Initialize highlight groups
-  if new_diagnostics.options.colored then
+  if self.options.colored then
-    new_diagnostics.highlight_groups = {
+    self.highlight_groups = {
       error = modules.highlight.create_component_highlight_group(
-        new_diagnostics.options.diagnostics_color.error,
+        self.options.diagnostics_color.error,
         'diagnostics_error',
-        new_diagnostics.options
+        self.options
       ),
       warn = modules.highlight.create_component_highlight_group(
-        new_diagnostics.options.diagnostics_color.warn,
+        self.options.diagnostics_color.warn,
         'diagnostics_warn',
-        new_diagnostics.options
+        self.options
       ),
       info = modules.highlight.create_component_highlight_group(
-        new_diagnostics.options.diagnostics_color.info,
+        self.options.diagnostics_color.info,
         'diagnostics_info',
-        new_diagnostics.options
+        self.options
       ),
       hint = modules.highlight.create_component_highlight_group(
-        new_diagnostics.options.diagnostics_color.hint,
+        self.options.diagnostics_color.hint,
         'diagnostics_hint',
-        new_diagnostics.options
+        self.options
       ),
     }
   end
 
   -- Error out no source
-  if #new_diagnostics.options.sources < 1 then
+  if #self.options.sources < 1 then
     print 'no sources for diagnostics configured'
     return ''
   end
   -- Initialize variable to store last update so we can use it in insert
   -- mode for no update_in_insert
-  new_diagnostics.last_update = ''
+  self.last_update = ''
-  return new_diagnostics
 end
 
-Diagnostics.update_status = function(self)
+function M:update_status()
   if not self.options.update_in_insert and vim.api.nvim_get_mode().mode:sub(1, 1) == 'i' then
     return self.last_update
   end
@@ -175,7 +174,7 @@ Diagnostics.update_status = function(self)
   return self.last_update
 end
 
-Diagnostics.diagnostic_sources = {
+M.diagnostic_sources = {
   nvim_lsp = function()
     local error_count = vim.lsp.diagnostic.get_count(0, 'Error')
     local warning_count = vim.lsp.diagnostic.get_count(0, 'Warning')
@@ -220,11 +219,11 @@ Diagnostics.diagnostic_sources = {
   end,
 }
 
-Diagnostics.get_diagnostics = function(sources)
+M.get_diagnostics = function(sources)
   local result = {}
   for index, source in ipairs(sources) do
     if type(source) == 'string' then
-      local error_count, warning_count, info_count, hint_count = Diagnostics.diagnostic_sources[source]()
+      local error_count, warning_count, info_count, hint_count = M.diagnostic_sources[source]()
       result[index] = {
         error = error_count,
         warn = warning_count,
@@ -245,4 +244,4 @@ Diagnostics.get_diagnostics = function(sources)
   return result
 end
 
-return Diagnostics
+return M

lua/lualine/components/diff.lua

@@ -7,7 +7,7 @@ local modules = lualine_require.lazy_require {
   highlight = 'lualine.highlight',
   Job = 'lualine.utils.job',
 }
-local Diff = lualine_require.require('lualine.component'):new()
+local M = lualine_require.require('lualine.component'):extend()
 
 local function check_deprecated_options(options)
   if options.color_added or options.color_modified or options.color_removed then
@@ -35,12 +35,12 @@ end
 
 -- Vars
 -- variable to store git diff stats
-Diff.git_diff = nil
+M.git_diff = nil
 -- accumulates output from diff process
-Diff.diff_output_cache = {}
+M.diff_output_cache = {}
 -- variable to store git_diff job
-Diff.diff_job = nil
+M.diff_job = nil
-Diff.active_bufnr = '0'
+M.active_bufnr = '0'
 
 local diff_cache = {} -- Stores last known value of diff of a buffer
 
@@ -61,54 +61,52 @@ local default_options = {
 }
 
 -- Initializer
-Diff.new = function(self, options, child)
+function M:init(options)
-  local new_instance = self._parent:new(options, child or Diff)
+  M.super.init(self, options)
-  new_instance.options = vim.tbl_deep_extend('keep', new_instance.options or {}, default_options)
+  self.options = vim.tbl_deep_extend('keep', self.options or {}, default_options)
-  check_deprecated_options(new_instance.options)
+  check_deprecated_options(self.options)
   -- create highlights and save highlight_name in highlights table
-  if new_instance.options.colored then
+  if self.options.colored then
-    new_instance.highlights = {
+    self.highlights = {
       added = modules.highlight.create_component_highlight_group(
-        new_instance.options.diff_color.added,
+        self.options.diff_color.added,
         'diff_added',
-        new_instance.options
+        self.options
       ),
       modified = modules.highlight.create_component_highlight_group(
-        new_instance.options.diff_color.modified,
+        self.options.diff_color.modified,
         'diff_modified',
-        new_instance.options
+        self.options
       ),
       removed = modules.highlight.create_component_highlight_group(
-        new_instance.options.diff_color.removed,
+        self.options.diff_color.removed,
         'diff_removed',
-        new_instance.options
+        self.options
       ),
     }
   end
 
-  Diff.diff_checker_enabled = type(new_instance.options.source) ~= 'function'
+  M.diff_checker_enabled = type(self.options.source) ~= 'function'
 
-  if Diff.diff_checker_enabled then
+  if M.diff_checker_enabled then
     -- setup internal source
     modules.utils.define_autocmd('BufEnter', "lua require'lualine.components.diff'.update_diff_args()")
     modules.utils.define_autocmd('BufWritePost', "lua require'lualine.components.diff'.update_git_diff()")
-    Diff.update_diff_args()
+    M.update_diff_args()
   end
-
-  return new_instance
 end
 
 -- Function that runs everytime statusline is updated
-Diff.update_status = function(self, is_focused)
+function M:update_status(is_focused)
   local git_diff
-  if Diff.diff_checker_enabled then
+  if M.diff_checker_enabled then
-    if Diff.active_bufnr ~= vim.g.actual_curbuf then
+    if M.active_bufnr ~= vim.g.actual_curbuf then
       -- Workaround for https://github.com/hoob3rt/lualine.nvim/issues/286
       -- See upstream issue https://github.com/neovim/neovim/issues/15300
       -- Diff is out of sync re sync it.
-      Diff.update_diff_args()
+      M.update_diff_args()
     end
-    git_diff = Diff.git_diff
+    git_diff = M.git_diff
   else
     git_diff = self.options.source()
   end
@@ -154,15 +152,15 @@ end
 --    removed = removed_count,
 -- }
 -- error_code = { added = -1, modified = -1, removed = -1 }
-function Diff.get_sign_count()
+function M.get_sign_count()
-  if Diff.diff_checker_enabled then
+  if M.diff_checker_enabled then
-    Diff.update_diff_args()
+    M.update_diff_args()
   end
-  return Diff.git_diff or { added = -1, modified = -1, removed = -1 }
+  return M.git_diff or { added = -1, modified = -1, removed = -1 }
 end
 
 -- process diff data and update git_diff{ added, removed, modified }
-function Diff.process_diff(data)
+function M.process_diff(data)
   -- Adapted from https://github.com/wbthomason/nvim-vcs.lua
   local added, removed, modified = 0, 0, 0
   for _, line in ipairs(data) do
@@ -185,19 +183,19 @@ function Diff.process_diff(data)
       end
     end
   end
-  Diff.git_diff = { added = added, modified = modified, removed = removed }
+  M.git_diff = { added = added, modified = modified, removed = removed }
 end
 
 -- Updates the job args
-function Diff.update_diff_args()
+function M.update_diff_args()
   -- Donn't show git diff when current buffer doesn't have a filename
-  Diff.active_bufnr = tostring(vim.fn.bufnr())
+  M.active_bufnr = tostring(vim.fn.bufnr())
   if #vim.fn.expand '%' == 0 then
-    Diff.diff_args = nil
+    M.diff_args = nil
-    Diff.git_diff = nil
+    M.git_diff = nil
     return
   end
-  Diff.diff_args = {
+  M.diff_args = {
     cmd = string.format(
       [[git -C %s --no-pager diff --no-color --no-ext-diff -U0 -- %s]],
       vim.fn.expand '%:h',
@@ -205,40 +203,40 @@ function Diff.update_diff_args()
     ),
     on_stdout = function(_, data)
       if next(data) then
-        Diff.diff_output_cache = vim.list_extend(Diff.diff_output_cache, data)
+        M.diff_output_cache = vim.list_extend(M.diff_output_cache, data)
       end
     end,
     on_stderr = function(_, data)
       data = table.concat(data, '\n')
       if #data > 1 or (#data == 1 and #data[1] > 0) then
-        Diff.git_diff = nil
+        M.git_diff = nil
-        Diff.diff_output_cache = {}
+        M.diff_output_cache = {}
       end
     end,
     on_exit = function()
-      if #Diff.diff_output_cache > 0 then
+      if #M.diff_output_cache > 0 then
-        Diff.process_diff(Diff.diff_output_cache)
+        M.process_diff(M.diff_output_cache)
       else
-        Diff.git_diff = { added = 0, modified = 0, removed = 0 }
+        M.git_diff = { added = 0, modified = 0, removed = 0 }
       end
-      diff_cache[vim.fn.bufnr()] = Diff.git_diff
+      diff_cache[vim.fn.bufnr()] = M.git_diff
     end,
   }
-  Diff.update_git_diff()
+  M.update_git_diff()
 end
 
 -- Update git_diff veriable
-function Diff.update_git_diff()
+function M.update_git_diff()
-  if Diff.diff_args then
+  if M.diff_args then
-    Diff.diff_output_cache = {}
+    M.diff_output_cache = {}
-    if Diff.diff_job then
+    if M.diff_job then
-      Diff.diff_job:stop()
+      M.diff_job:stop()
     end
-    Diff.diff_job = modules.Job(Diff.diff_args)
+    M.diff_job = modules.Job(M.diff_args)
-    if Diff.diff_job then
+    if M.diff_job then
-      Diff.diff_job:start()
+      M.diff_job:start()
     end
   end
 end
 
-return Diff
+return M

lua/lualine/components/encoding.lua

@@ -1,9 +1,9 @@
 -- Copyright (c) 2020-2021 hoob3rt
 -- MIT license, see LICENSE for more details.
-local Encoding = require('lualine.component'):new()
+local M = require('lualine.component'):extend()
 
-Encoding.update_status = function()
+M.update_status = function()
   return [[%{strlen(&fenc)?&fenc:&enc}]]
 end
 
-return Encoding
+return M

lua/lualine/components/fileformat.lua

@@ -1,20 +1,20 @@
 -- Copyright (c) 2020-2021 shadmansaleh
 -- MIT license, see LICENSE for more details.
-local FileFormat = require('lualine.component'):new()
+local M = require('lualine.component'):extend()
 
 -- stylua: ignore
-FileFormat.icon = {
+M.icon = {
   unix = '', -- e712
   dos  = '', -- e70f
   mac  = ''  -- e711
 }
 
-FileFormat.update_status = function(self)
+M.update_status = function(self)
   if self.options.icons_enabled and not self.options.icon then
     local format = vim.bo.fileformat
-    return FileFormat.icon[format] or format
+    return M.icon[format] or format
   end
   return vim.bo.fileformat
 end
 
-return FileFormat
+return M

lua/lualine/components/filename.lua

@@ -1,6 +1,6 @@
 -- Copyright (c) 2020-2021 shadmansaleh
 -- MIT license, see LICENSE for more details.
-local FileName = require('lualine.component'):new()
+local M = require('lualine.component'):extend()
 
 local default_options = {
   symbols = { modified = '[+]', readonly = '[-]' },
@@ -18,13 +18,12 @@ local function shorten_path(path, sep)
   return path:gsub(string.format('([^%s])[^%s]+%%%s', sep, sep, sep), '%1' .. sep, 1)
 end
 
-FileName.new = function(self, options, child)
+M.init = function(self, options)
-  local new_instance = self._parent:new(options, child or FileName)
+  M.super.init(self, options)
-  new_instance.options = vim.tbl_deep_extend('keep', new_instance.options or {}, default_options)
+  self.options = vim.tbl_deep_extend('keep', self.options or {}, default_options)
-  return new_instance
 end
 
-FileName.update_status = function(self)
+M.update_status = function(self)
   local data
   if self.options.path == 1 then
     -- relative path
@@ -63,4 +62,4 @@ FileName.update_status = function(self)
   return data
 end
 
-return FileName
+return M

lua/lualine/components/filesize.lua

@@ -1,6 +1,6 @@
 -- Copyright (c) 2020-2021 shadmansaleh
 -- MIT license, see LICENSE for more details.
-local M = require('lualine.component'):new()
+local M = require('lualine.component'):extend()
 
 M.update_status = function()
   local file = vim.fn.expand '%:p'

lua/lualine/components/filetype.lua

@@ -5,7 +5,7 @@ local modules = lualine_require.lazy_require {
   highlight = 'lualine.highlight',
   utils = 'lualine.utils.utils',
 }
-local FileType = lualine_require.require('lualine.component'):new()
+local M = lualine_require.require('lualine.component'):extend()
 
 local function check_deprecated_options(options)
   local function rename_notice(before, now)
@@ -33,18 +33,17 @@ local default_options = {
   icon_only = false,
 }
 
-function FileType:new(options, child)
+function M:init(options)
-  local new_instance = self._parent:new(options, child or FileType)
+  M.super.init(self, options)
-  new_instance.options = vim.tbl_deep_extend('keep', new_instance.options or {}, default_options)
+  self.options = vim.tbl_deep_extend('keep', self.options or {}, default_options)
-  check_deprecated_options(new_instance.options)
+  check_deprecated_options(self.options)
-  return new_instance
 end
 
-function FileType.update_status()
+function M.update_status()
   return vim.bo.filetype or ''
 end
 
-function FileType:apply_icon()
+function M:apply_icon()
   if not self.options.icons_enabled then
     return
   end
@@ -87,4 +86,4 @@ function FileType:apply_icon()
   end
 end
 
-return FileType
+return M

lua/lualine/components/hostname.lua

@@ -1,7 +1,7 @@
 -- Copyright (c) 2020-2021 hoob3rt
 -- MIT license, see LICENSE for more details.
-local HostName = require('lualine.component'):new()
+local M = require('lualine.component'):extend()
 
-HostName.update_status = vim.loop.os_gethostname
+M.update_status = vim.loop.os_gethostname
 
-return HostName
+return M

lua/lualine/components/location.lua

@@ -1,9 +1,9 @@
 -- Copyright (c) 2020-2021 hoob3rt
 -- MIT license, see LICENSE for more details.
-local Location = require('lualine.component'):new()
+local M = require('lualine.component'):extend()
 
-Location.update_status = function()
+M.update_status = function()
   return [[%3l:%-2c]]
 end
 
-return Location
+return M

lua/lualine/components/mode.lua

@@ -1,9 +1,10 @@
 -- Copyright (c) 2020-2021 hoob3rt
 -- MIT license, see LICENSE for more details.
 local require = require('lualine_require').require
-local Mode = require('lualine.component'):new()
 local get_mode = require('lualine.utils.mode').get_mode
 
-Mode.update_status = get_mode
+local M = require('lualine.component'):extend()
 
-return Mode
+M.update_status = get_mode
+
+return M

lua/lualine/components/progress.lua

@@ -1,9 +1,9 @@
 -- Copyright (c) 2020-2021 hoob3rt
 -- MIT license, see LICENSE for more details.
-local Progress = require('lualine.component'):new()
+local M = require('lualine.component'):extend()
 
-Progress.update_status = function()
+M.update_status = function()
   return [[%3P]]
 end
 
-return Progress
+return M

lua/lualine/components/special/eval_func_component.lua

@@ -1,36 +1,35 @@
 -- Copyright (c) 2020-2021 shadmansaleh
 -- MIT license, see LICENSE for more details.
+local M = require('lualine.component'):extend()
 
-local EvalFuncComponent = require('lualine.component'):new()
+function M:update_status()
-
-EvalFuncComponent.update_status = function(self)
   local component = self.options[1]
   local ok, status
   if self.options.type == nil then
-    ok, status = pcall(EvalFuncComponent.lua_eval, component)
+    ok, status = pcall(M.lua_eval, component)
     if not ok then
-      status = EvalFuncComponent.vim_function(component)
+      status = M.vim_function(component)
     end
   else
     if self.options.type == 'luae' then
-      ok, status = pcall(EvalFuncComponent.lua_eval, component)
+      ok, status = pcall(M.lua_eval, component)
       if not ok then
         status = nil
       end
     elseif self.options.type == 'vimf' then
-      status = EvalFuncComponent.vim_function(component)
+      status = M.vim_function(component)
     end
   end
   return status
 end
 
-EvalFuncComponent.lua_eval = function(code)
+function M.lua_eval(code)
   local result = loadstring('return ' .. code)()
   assert(result, 'String expected got nil')
   return tostring(result)
 end
 
-EvalFuncComponent.vim_function = function(name)
+function M.vim_function(name)
   -- vim function component
   local ok, return_val = pcall(vim.api.nvim_call_function, name, {})
   if not ok then
@@ -40,4 +39,4 @@ EvalFuncComponent.vim_function = function(name)
   return ok and return_val or ''
 end
 
-return EvalFuncComponent
+return M

lua/lualine/components/special/function_component.lua

@@ -1,8 +1,8 @@
 -- Copyright (c) 2020-2021 shadmansaleh
 -- MIT license, see LICENSE for more details.
-local FunctionComponent = require('lualine.component'):new()
+local M = require('lualine.component'):extend()
 
-FunctionComponent.update_status = function(self, is_focused)
+M.update_status = function(self, is_focused)
   -- 1st element in options table is the function provided by config
   local ok, retval
   ok, retval = pcall(self.options[1], self, is_focused)
@@ -18,4 +18,4 @@ FunctionComponent.update_status = function(self, is_focused)
   return retval
 end
 
-return FunctionComponent
+return M

lua/lualine/components/special/vim_var_component.lua

@@ -1,7 +1,8 @@
 -- Copyright (c) 2020-2021 shadmansaleh
 -- MIT license, see LICENSE for more details.
-local VarComponent = require('lualine.component'):new()
+local M = require('lualine.component'):extend()
-VarComponent.update_status = function(self)
+
+function M:update_status()
   local component = self.options[1]
   -- vim veriable component
   -- accepts g:, v:, t:, w:, b:, o, go:, vo:, to:, wo:, bo:
@@ -31,4 +32,4 @@ VarComponent.update_status = function(self)
   return ok and return_val or ''
 end
 
-return VarComponent
+return M

lua/lualine/components/tabs.lua

@@ -1,6 +1,6 @@
 -- Copyright (c) 2020-2021 shadmansaleh
 -- MIT license, see LICENSE for more details.
-local Tabs = require('lualine.component'):new()
+local M = require('lualine.component'):extend()
 local highlight = require 'lualine.highlight'
 
 local default_options = {
@@ -103,30 +103,29 @@ function Tab:separator_after()
   end
 end
 
-function Tabs:new(options, child)
+function M:init(options)
-  local newObj = self._parent:new(options, child or Tabs)
+  M.super.init(self, options)
   default_options.tabs_color = {
     active = get_hl(options.self.section, true),
     inactive = get_hl(options.self.section, false),
   }
-  newObj.options = vim.tbl_deep_extend('keep', newObj.options or {}, default_options)
+  self.options = vim.tbl_deep_extend('keep', self.options or {}, default_options)
   -- stylua: ignore
-  newObj.highlights = {
+  self.highlights = {
     active = highlight.create_component_highlight_group(
-      newObj.options.tabs_color.active,
+      self.options.tabs_color.active,
       'tabs_active',
-      newObj.options
+      self.options
     ),
     inactive = highlight.create_component_highlight_group(
-      newObj.options.tabs_color.inactive,
+      self.options.tabs_color.inactive,
       'tabs_active',
-      newObj.options
+      self.options
     ),
   }
-  return newObj
 end
 
-function Tabs:update_status()
+function M:update_status()
   local data = {}
   local tabs = {}
   for t = 1, vim.fn.tabpagenr '$' do
@@ -214,4 +213,4 @@ vim.cmd [[
   endfunction
 ]]
 
-return Tabs
+return M

lua/lualine/utils/class.lua

@@ -0,0 +1,43 @@
+-- Adapted from https://github.com/rxi/classic/blob/master/classic.lua
+local Object = {}
+
+Object.__index = Object
+
+-- luacheck: push no unused args
+-- Initializer
+function Object:init(...) end
+-- luacheck: pop
+
+-- Extened base class to create a child class
+function Object:extend()
+  local cls = {}
+  for k, v in pairs(self) do
+    if k:find '__' == 1 then
+      cls[k] = v
+    end
+  end
+  cls.__index = cls
+  cls.super = self
+  setmetatable(cls, self)
+  return cls
+end
+
+-- luacheck: push no unused args
+function Object:__tostring()
+  return 'Object'
+end
+-- luacheck: pop
+
+-- Creates a new object
+function Object:new(...)
+  local obj = setmetatable({}, self)
+  obj:init(...)
+  return obj
+end
+
+-- Creates a new object
+function Object:__call(...)
+  return self:new(...)
+end
+
+return Object

lua/lualine/utils/loader.lua

@@ -12,13 +12,13 @@ local sep = lualine_require.sep
 
 local component_types = {
   luaf = function(component)
-    return require('lualine.components.special.function_component'):new(component)
+    return require 'lualine.components.special.function_component'(component)
   end,
   mod = function(component)
     local ok, loaded_component = pcall(require, 'lualine.components.' .. component[1])
     if ok then
       component.component_name = component[1]
-      loaded_component = loaded_component:new(component)
+      loaded_component = loaded_component(component)
       return loaded_component
     end
   end,
@@ -27,13 +27,13 @@ local component_types = {
     component[1] = function()
       return stl_expr
     end
-    return require('lualine.components.special.function_component'):new(component)
+    return require 'lualine.components.special.function_component'(component)
   end,
   var = function(component)
-    return require('lualine.components.special.vim_var_component'):new(component)
+    return require 'lualine.components.special.vim_var_component'(component)
   end,
   ['_'] = function(component)
-    return require('lualine.components.special.eval_func_component'):new(component)
+    return require 'lualine.components.special.eval_func_component'(component)
   end,
 }
 

lua/tests/helpers.lua

@@ -17,7 +17,7 @@ M.assert_component = function(component, opts, result)
   if component == nil then
     component = 'special.function_component'
   end
-  local comp = require('lualine.components.' .. component):new(opts)
+  local comp = require('lualine.components.' .. component)(opts)
   eq(result, comp:draw(opts.hl))
 end
 

lua/tests/spec/component_spec.lua

@@ -12,20 +12,20 @@ local stub = require 'luassert.stub'
 describe('Component:', function()
   it('can select separators', function()
     local opts = build_component_opts()
-    local comp = require('lualine.components.special.function_component'):new(opts)
+    local comp = require 'lualine.components.special.function_component'(opts)
     -- correct for lualine_c
     eq('', comp.options.separator)
     local opts2 = build_component_opts { self = { section = 'lualine_y' } }
-    local comp2 = require('lualine.components.special.function_component'):new(opts2)
+    local comp2 = require 'lualine.components.special.function_component'(opts2)
     -- correct for lualine_u
     eq('', comp2.options.separator)
   end)
 
   it('can provide unique identifier', function()
     local opts1 = build_component_opts()
-    local comp1 = require('lualine.components.special.function_component'):new(opts1)
+    local comp1 = require 'lualine.components.special.function_component'(opts1)
     local opts2 = build_component_opts()
-    local comp2 = require('lualine.components.special.function_component'):new(opts2)
+    local comp2 = require 'lualine.components.special.function_component'(opts2)
     neq(comp1.component_no, comp2.component_no)
   end)
 
@@ -35,7 +35,7 @@ describe('Component:', function()
     local hl = require 'lualine.highlight'
     stub(hl, 'create_component_highlight_group')
     hl.create_component_highlight_group.returns 'MyCompHl'
-    local comp1 = require('lualine.components.special.function_component'):new(opts1)
+    local comp1 = require 'lualine.components.special.function_component'(opts1)
     eq('MyCompHl', comp1.options.color_highlight)
     -- color highlight wan't in options when create_comp_hl was
     -- called so remove it before assert
@@ -46,7 +46,7 @@ describe('Component:', function()
     local opts2 = build_component_opts { color = color }
     stub(hl, 'create_component_highlight_group')
     hl.create_component_highlight_group.returns 'MyCompLinkedHl'
-    local comp2 = require('lualine.components.special.function_component'):new(opts2)
+    local comp2 = require 'lualine.components.special.function_component'(opts2)
     eq('MyCompLinkedHl', comp2.options.color_highlight)
     -- color highlight wan't in options when create_comp_hl was
     -- called so remove it before assert
@@ -206,7 +206,7 @@ describe('Component:', function()
         padding = 0,
         color = 'MyHl',
       }
-      local comp = require('lualine.components.special.function_component'):new(opts)
+      local comp = require 'lualine.components.special.function_component'(opts)
       local custom_link_hl_name = 'lualine_' .. comp.options.component_name .. '_no_mode'
       eq('%#' .. custom_link_hl_name .. '#test', comp:draw(opts.hl))
       local opts2 = build_component_opts {
@@ -217,7 +217,7 @@ describe('Component:', function()
       local hl = require 'lualine.highlight'
       stub(hl, 'component_format_highlight')
       hl.component_format_highlight.returns '%#MyCompHl#'
-      local comp2 = require('lualine.components.special.function_component'):new(opts2)
+      local comp2 = require 'lualine.components.special.function_component'(opts2)
       assert_component(nil, opts2, '%#MyCompHl#test')
       assert.stub(hl.component_format_highlight).was_called_with(comp2.options.color_highlight)
       hl.component_format_highlight:revert()

lua/tests/spec/utils_spec.lua

@@ -59,8 +59,8 @@ describe('Section genarator', function()
   it('can draw', function()
     local opts = build_component_opts { section_separators = { left = '', right = '' } }
     local section = {
-      require('lualine.components.special.function_component'):new(opts),
+      require 'lualine.components.special.function_component'(opts),
-      require('lualine.components.special.function_component'):new(opts),
+      require 'lualine.components.special.function_component'(opts),
     }
     eq('%#lualine_MySection_normal# test %#lualine_MySection_normal# test ', sec.draw_section(section, 'MySection'))
   end)
@@ -78,9 +78,9 @@ describe('Section genarator', function()
     }
     require('lualine.highlight').create_highlight_groups(require 'lualine.themes.gruvbox')
     local section = {
-      require('lualine.components.special.function_component'):new(opts),
+      require 'lualine.components.special.function_component'(opts),
-      require('lualine.components.special.function_component'):new(opts_colored),
+      require 'lualine.components.special.function_component'(opts_colored),
-      require('lualine.components.special.function_component'):new(opts),
+      require 'lualine.components.special.function_component'(opts),
     }
     local highlight_name2 = 'lualine_' .. section[2].options.component_name .. '_no_mode'
     -- Removes separator on string color
@@ -88,14 +88,14 @@ describe('Section genarator', function()
       '%#lualine_MySection_normal# test %#' .. highlight_name2 .. '#' .. ' test %#lualine_MySection_normal# test ',
       sec.draw_section(section, 'MySection')
     )
-    section[2] = require('lua.lualine.components.special.function_component'):new(opts_colored2)
+    section[2] = require 'lua.lualine.components.special.function_component'(opts_colored2)
     local highlight_name = '%#lualine_c_' .. section[2].options.component_name .. '_normal#'
     -- Removes separator on color with bg
     eq(
       '%#lualine_MySection_normal# test ' .. highlight_name .. ' test %#lualine_MySection_normal# test ',
       sec.draw_section(section, 'MySection')
     )
-    section[2] = require('lua.lualine.components.special.function_component'):new(opts_colored3)
+    section[2] = require 'lua.lualine.components.special.function_component'(opts_colored3)
     highlight_name2 = '%#lualine_c_' .. section[2].options.component_name .. '_normal#'
     -- Doesn't remove separator on color without bg
     eq(