Limits on Windows environment variable nesting?

Question

So, is there a limit to how deeply environment variables can be nested in Windows? I do a lot of development work and I'm trying to set up my development environment vars, and a lot of them nest off each other, ie.

GLEW=%THIRD_PARTY_ROOT%\GLEW
GLEW_1_5_5=%GLEW%\glew-1.5.5
GLEW_BIN_PATH=%GLEW_ROOT%\bin
GLEW_INCLUDE_PATH=%GLEW_ROOT%\include
GLEW_LIB_PATH=%GLEW_ROOT%\lib
GLEW_ROOT=%GLEW_1_5_5%

OSG=%THIRD_PARTY_ROOT%\OpenSceneGraph
OSG_2_8_3=%OSG%\OpenSceneGraph-2.8.3
OSG_BIN_PATH=%OSG_ROOT%\bin
OSG_INCLUDE_PATH=%OSG_ROOT%\include
OSG_LIB_PATH=%OSG_ROOT%\lib
OSG_ROOT=%OSG_2_8_3%

THIRD_PARTY_ROOT=C:\dev\third-party

But I was having a heck of a time getting them to actually expand properly. For a while when I looked at the output of set, I was just getting what looked like they were being expanded in order and so any ones that depended on foo_ROOT weren't being expanded properly. I tried enabling delayed expansion and that didn't help, but restarting seemed to... so maybe delayed expansion required a restart..

Either way, I have GLEW_BIN_PATH and OSG_BIN_PATH in my PATH variable and they refuse to expand. This is really frustrating because the dll's are residing there and of course I can get evvvverything else to expand... any thoughts?

Edit: I have them in the PATH variable as:

[everything else....];%GLEW_BIN_PATH%;%OSG_BIN_PATH%

So I'm not seeing an obvious cause to keep them from expanding out..

Answer 1

I've had success with escaping the percent sign:

GLEW=%%THIRD_PARTY_ROOT%%\GLEW

THIRD_PARTY_ROOT=C:\dev\third-party

C:\>set GLEW
GLEW=C:\dev\third-party\GLEW

When viewing the variable from the Windows Environment Variable window, it will display as

GLEW | %THIRD_PARTY_ROOT%\GLEW

Note: The double percent signs will only work inside a script. If using on the command line, use the caret escape character (e.g. GLEW=^%THIRD_PARTY_ROOT^%\GLEW).