More general implementation.

python/paddle/v2/fluid/io.py

@@ -186,12 +186,16 @@ def load_persistables(executor, dirname, main_program=None):
 def get_inference_program(target_vars, main_program=None):
     if main_program is None:
         main_program = default_main_program()
-    if isinstance(target_vars, Evaluator):
-        target_vars = target_vars.states + target_vars.metrics
     if not isinstance(target_vars, list):
         target_vars = [target_vars]
-
-    pruned_program = main_program.prune(targets=target_vars)
+    vars = []
+    for var in target_vars:
+        if isinstance(var, Evaluator):
+            vars.append(var.states)
+            vars.append(var.metrics)
+        else:
+            vars.append(var)
+    pruned_program = main_program.prune(targets=vars)
     inference_program = pruned_program.inference_optimize()
     return inference_program