Enhance: Cleanup eval_lua component and document it

README.md

@@ -177,7 +177,7 @@ sections = {lualine_a = {'FugitiveHead'}}
 <details>
 <summary><b>Using variables as lualine component</b></summary>
 
-You can use variables from vim and lua globals as a lualine component
+You can use variables from vim a lualine component
 Variables from g:, v:, t:, w:, b:, o, go:, vo:, to:, wo:, bo: scopes
 can be used. Scopes ending with o are options usualy accessed with `&` in vimscript
 
@@ -187,6 +187,22 @@ sections = {lualine_a = {'g:coc_status', 'bo:filetype'}}
 
 </details>
 
+<details>
+<summary><b>Using lua expressions as lualine component</b></summary>
+
+You can use any valid lua expression as a component . This allows global
+variables to be used as  a component too. Even require statements can be used to access values returned by specific scripts.
+One liner functions can be inlined by utilizeing this .
+
+For exmaple this will show day of the week.
+And 2nd one will display current value of global variabke data.
+
+```lua
+sections = {lualine_c = {"os.data('%a')", 'data'}}
+```
+
+</details>
+
 <details>
 <summary><b>Options for components</b></summary>
 

doc/lualine.txt

@@ -193,13 +193,27 @@ You can use vim functions as a lualine component
 
 Using variables as lualine component~
 
-You can use variables from vim and lua globals as a lualine component
-Variables from g:, v:, t:, w:, b:, o, go:, vo:, to:, wo:, bo: scopes
-can be used. Scopes ending with o are options usualy accessed with `&` in vimscript
+You can use variables from vim. Variables from g:, v:, t:,
+w:, b:, o, go:, vo:, to:, wo:, bo: scopes can be used.
+Scopes ending with o are options usualy accessed with `&` in
+vimscript
 
 >
     sections = {lualine_a = {'g:coc_status', 'bo:filetype'}}
 <
+Using lua expressions as lualine component~
+
+You can use any valid lua expression as a component . This
+allows global variables to be used as  a component too. Even
+require statements can be used to access values returned by
+specific scripts.  One liner functions can be inlined by
+utilizeing this .
+
+For exmaple this will show day of the week.  And 2nd one
+will display current value of global variabke data.
+>
+    sections = {lualine_c = {"os.data('%a')", 'data'}}
+<
 
 --------------------------------------------------------------------------------
 CUSTOM OPTIONS FOR COMPONENTS                        *lualine_custom_options*

lua/lualine/components/special/eval_func_component.lua

@@ -2,22 +2,13 @@ local EvalFuncComponent = require('lualine.component'):new()
 
 EvalFuncComponent.update_status = function(self)
   local component = self.options[1]
-  local ok, status = EvalFuncComponent.evallua(component)
+  local ok, status = pcall(EvalFuncComponent.eval_lua, component)
   if not ok then status = EvalFuncComponent.vim_function(component) end
   return status
 end
 
-EvalFuncComponent.evallua = function(code)
-  if loadstring(string.format('return %s ~= nil', code)) and
-      loadstring(string.format([[return %s ~= nil]], code))() then
-    -- lua veriable component
-    return true, loadstring(string.format(
-                                [[
-    local ok, return_val = pcall(tostring, %s)
-    if ok then return return_val end
-    return '']], code))()
-  end
-  return false, ''
+EvalFuncComponent.eval_lua = function(code)
+  return tostring(loadstring('return '..code)())
 end
 
 EvalFuncComponent.vim_function = function(name)