Provide v:shell_error equivalent (g:xolox#shell#make_exit_code)

See issue #8 on GitHub:
  #8

Author: xolox

README.md

@@ -40,6 +40,8 @@ Note that on UNIX if the environment variable `$DISPLAY` is empty the plug-in wi
 
 This command is a very simple replacement for the [:make][make] command that does not pop up a console window on Windows. It doesn't come with all of the bells and whistles that Vim's built-in make command does but it should work.
 
+Because Vim's [v:shell_error][shell_error] variable is read only (which means it cannot be set by a Vim plug-in) the vim-shell plug-in defines its own variable with the exit code of the `make` process executed by `:MakeWithShell`. This variable is called `g:xolox#shell#make_exit_code`. The semantics are exactly the same as for [v:shell_error][shell_error].
+
 ### The `xolox#misc#os#exec()` function
 
 This function enables other Vim plug-ins to execute external commands in the background (i.e. asynchronously) *without opening a command prompt window on Windows*. For example try to execute the following command on Windows ([vimrun.exe][vimrun] is only included with Vim for Windows because it isn't needed on other platforms):
@@ -135,6 +137,7 @@ This software is licensed under the [MIT license](http://en.wikipedia.org/wiki/M
 [make]: http://vimdoc.sourceforge.net/htmldoc/quickfix.html#:make
 [sh_opt]: http://vimdoc.sourceforge.net/htmldoc/options.html#%27shell%27
 [shcf_opt]: http://vimdoc.sourceforge.net/htmldoc/options.html#%27shellcmdflag%27
+[shell_error]: http://vimdoc.sourceforge.net/htmldoc/eval.html#v:shell_error
 [system]: http://vimdoc.sourceforge.net/htmldoc/eval.html#system()
 [vim]: http://www.vim.org/
 [vim_scripts_entry]: http://www.vim.org/scripts/script.php?script_id=3123

autoload/xolox/shell.vim

@@ -1,9 +1,9 @@
 " Vim auto-load script
 " Author: Peter Odding <peter@peterodding.com>
-" Last Change: May 13, 2013
+" Last Change: May 14, 2013
 " URL: http://peterodding.com/code/vim/shell/
 
-let g:xolox#shell#version = '0.12.1'
+let g:xolox#shell#version = '0.12.2'
 
 call xolox#misc#compat#check('shell', 3)
 
@@ -154,9 +154,14 @@ endfunction
 function! s:make_cmd(command)
   let command = a:command . ' 2>&1'
   let result = xolox#misc#os#exec({'command': command, 'check': 0})
+  let g:xolox#shell#make_exit_code = result['exit_code']
   return join(result['stdout'], "\n")
 endfunction
 
+if !exists('g:xolox#shell#make_exit_code')
+  let g:xolox#shell#make_exit_code = 0
+endif
+
 function! xolox#shell#maximize(...) " {{{1
   " Show/hide Vim's menu, tool bar and/or tab line.
   let new_state = a:0 == 0 ? !s:maximized : a:1

doc/shell.txt

@@ -107,6 +107,12 @@ This command is a very simple replacement for the |:make| command that does not
 pop up a console window on Windows. It doesn't come with all of the bells and
 whistles that Vim's built-in make command does but it should work.
 
+Because Vim's |v:shell_error| variable is read only (which means it cannot be
+set by a Vim plug-in) the vim-shell plug-in defines its own variable with the
+exit code of the 'make' process executed by |:MakeWithShell|. This variable is
+called 'g:xolox#shell#make_exit_code'. The semantics are exactly the same as
+for |v:shell_error|.
+
 -------------------------------------------------------------------------------
 The *xolox#misc#os#exec()* function