vimrc: Refactor for sustainability and portability

Author: tony

vimrc

@@ -1,13 +1,15 @@
 "------------------------------------------------------------------------------
-" Basic Recommended Settings (optional)
+" Basic Recommended Settings
 "------------------------------------------------------------------------------
 if v:version >= 800
   set nocompatible
   syntax on
   filetype plugin indent on
 endif
 
-" For older Vim versions (if needed):
+"------------------------------------------------------------------------------
+" Fallback for older Vim (comment out if unnecessary)
+"------------------------------------------------------------------------------
 " set nocompatible
 " syntax enable
 " filetype plugin on
@@ -16,11 +18,19 @@ endif
 "------------------------------------------------------------------------------
 " Helper Function for Conditional Sourcing
 "------------------------------------------------------------------------------
-function! SourceIfExists(file) abort
-  if filereadable(expand(a:file))
-    execute 'source ' . fnameescape(a:file)
-  endif
-endfunction
+if has('vim9script')
+  def SourceIfExists(file: string)
+    if filereadable(expand(file))
+      execute 'source ' .. fnameescape(file)
+    endif
+  enddef
+else
+  function! SourceIfExists(file) abort
+    if filereadable(expand(a:file))
+      execute 'source ' . fnameescape(a:file)
+    endif
+  endfunction
+endif
 
 "------------------------------------------------------------------------------
 " Session / Directory Locations
@@ -50,8 +60,7 @@ set nowritebackup
 set noswapfile
 
 " Disable matchparen plugin (avoid glitchy behavior)
-let g:loaded_matchparen = 1
-" or use `:NoMatchParen`
+let g:loaded_matchparen = 1  " or use `:NoMatchParen`
 
 " Automatically cd to directory of opened file
 set autochdir
@@ -68,8 +77,11 @@ endif
 "------------------------------------------------------------------------------
 " Netrw Tweak
 "------------------------------------------------------------------------------
-" Fix netrw so that its buffer is hidden when leaving
-autocmd FileType netrw setlocal bufhidden=delete
+augroup MyNetrwFix
+  autocmd!
+  " Fix netrw so that its buffer is hidden on exit
+  autocmd FileType netrw setlocal bufhidden=delete
+augroup END
 
 "------------------------------------------------------------------------------
 " Truecolor Support (especially under tmux)
@@ -81,31 +93,30 @@ if exists('+termguicolors')
 endif
 
 "------------------------------------------------------------------------------
-" Source Shared/Plugin Files
+" Source Additional Files (Plugins, Settings, etc.)
 "------------------------------------------------------------------------------
-call SourceIfExists("$HOME/.vim/plugin_loader.vim")
+call SourceIfExists('$HOME/.vim/plugin_loader.vim')
 call plugin_loader#PlugInit()
 call settings#LoadSettings()
-call SourceIfExists("$HOME/.vim/settings/highlight.vim")
+call SourceIfExists('$HOME/.vim/settings/highlight.vim')
 
 "------------------------------------------------------------------------------
 " Color Schemes - Fallback Logic
 "------------------------------------------------------------------------------
+" Using an assumed function lib#ColorSchemeExists() to check if a scheme is present
 
-" Typically, you'll have a function or autoload script lib#ColorSchemeExists()
-" to check if a color scheme is installed. Keeping your existing logic:
-if has('nvim') && lib#ColorSchemeExists("tokyonight-moon")
+if has('nvim') && exists('*lib#ColorSchemeExists') && lib#ColorSchemeExists('tokyonight-moon')
   colorscheme tokyonight-moon
-elseif lib#ColorSchemeExists("tokyonight")
+elseif exists('*lib#ColorSchemeExists') && lib#ColorSchemeExists('tokyonight')
   colorscheme tokyonight
-elseif lib#ColorSchemeExists("catppuccin_mocha")
+elseif exists('*lib#ColorSchemeExists') && lib#ColorSchemeExists('catppuccin_mocha')
   colorscheme catppuccin_mocha
-elseif lib#ColorSchemeExists("gruvbox")
+elseif exists('*lib#ColorSchemeExists') && lib#ColorSchemeExists('gruvbox')
   colorscheme gruvbox
-elseif lib#ColorSchemeExists("gruvbox-material")
+elseif exists('*lib#ColorSchemeExists') && lib#ColorSchemeExists('gruvbox-material')
   let g:gruvbox_material_disable_italic_comment = 1
   colorscheme gruvbox-material
-elseif lib#ColorSchemeExists("everforest")
+elseif exists('*lib#ColorSchemeExists') && lib#ColorSchemeExists('everforest')
   if has('termguicolors')
     set termguicolors
   endif
@@ -114,7 +125,7 @@ elseif lib#ColorSchemeExists("everforest")
   let g:everforest_transparent_background = 2
   let g:everforest_disable_italic_comment = 1
   colorscheme everforest
-elseif lib#ColorSchemeExists("desert-warm-256")
+elseif exists('*lib#ColorSchemeExists') && lib#ColorSchemeExists('desert-warm-256')
   colorscheme desert-warm-256
 else
   colorscheme desert
@@ -123,4 +134,4 @@ endif
 "------------------------------------------------------------------------------
 " Local Customizations
 "------------------------------------------------------------------------------
-call SourceIfExists("$HOME/.vimrc.local")
+call SourceIfExists('$HOME/.vimrc.local')