now if THEANO_GPU is defined to something else then "", theano will automatically import cuda!

theano/__init__.py

@@ -63,6 +63,16 @@ import gof
 import floatX
 floatX.set_floatX()
 
+import config
+
+#if THEANO_GPU not defined: don't automaticcaly importe cuda
+#if THEANO_GPU defined to something else then "": automatically import cuda
+#   he will init cuda automatically if THEANO_GPU is not -1 or GPU
+#if cuda.use() and THEANO_GPU not defined or defined to "": init to device 0.
+#if THEANO_GPU defined to "-1" or "CPU", automatically import cuda, but don't init it.
+if config.THEANO_GPU not in [None,""]:
+    import theano.sandbox.cuda
+
 ## import scalar_opt
 
 import subprocess as _subprocess

theano/config.py

@@ -30,7 +30,7 @@ THEANO_BLAS_LDFLAGS = os.getenv('THEANO_BLAS_LDFLAGS','-lblas')
 
 #for gpu
 CUDA_ROOT = os.getenv('CUDA_ROOT')
-THEANO_GPU = os.getenv("THEANO_GPU",0)
+THEANO_GPU = os.getenv("THEANO_GPU")
 
 THEANO_DEFAULT_MODE = os.getenv('THEANO_DEFAULT_MODE','FAST_RUN')
 

theano/sandbox/cuda/__init__.py

@@ -61,7 +61,6 @@ except ImportError:
         set_cuda_disabled()
 
     if enable_cuda:
-        print __file__
 
         cuda_path=os.path.split(old_file)[0]
         code = open(os.path.join(cuda_path, "type_support.cu")).read()
@@ -115,6 +114,8 @@ def use(device=config.THEANO_GPU):
         # No successful call to use() has been made yet
         if device=="-1" or device=="CPU":
             return
+        if device in [None,""]:
+            device=0
         device=int(device)
         try:
             cuda_ndarray.gpu_init(device)
@@ -142,3 +143,6 @@ def handle_shared_float32(tf):
     else:
         raise NotImplementedError('removing our handler')
 
+
+if enable_cuda and config.THEANO_GPU not in [None, ""]:
+    use()