Check for variable definition instead of expansion

Author: josevalim

bin/elixir.bat

@@ -81,9 +81,6 @@ set beforeExtra=
 rem Option which determines whether the loop is over
 set endLoop=0
 
-rem Designates which mode / Elixir component to run as
-set runMode="cli"
-
 rem Designates the path to the current script
 set SCRIPT_PATH=%~dp0
 
@@ -106,7 +103,7 @@ if !endLoop! == 1 (
 )
 rem ******* EXECUTION OPTIONS **********************
 if !par!=="--werl"   (set useWerl=1 && goto startloop)
-if !par!=="+iex"     (set parsElixir=!parsElixir! +iex && set runMode="iex" && goto startloop)
+if !par!=="+iex"     (set parsElixir=!parsElixir! +iex && set useIEx=1 && goto startloop)
 if !par!=="+elixirc" (set parsElixir=!parsElixir! +elixirc && goto startloop)
 rem ******* EVAL PARAMETERS ************************
 if ""==!par:-e=! (
@@ -164,7 +161,7 @@ reg query HKCU\Console /v VirtualTerminalLevel 2>nul | findstr /e "0x1" >nul 2>n
 if %errorlevel% == 0 (
   set beforeExtra=-elixir ansi_enabled true !beforeExtra!
 )
-if !runMode! == "iex" (
+if defined useIEx (
   set beforeExtra=-s elixir start_iex !beforeExtra!
 ) else (
   set beforeExtra=-s elixir start_cli !beforeExtra!