fix: close #160

quafu/algorithms/interface_provider.py

@@ -12,14 +12,20 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from .interface.torch import TorchTransformer
-
-PROVIDERS = {"torch": TorchTransformer}
-
 
 class InterfaceProvider:
+    _init = False
+    _providers = {}
+
     @classmethod
     def get(cls, name: str):
-        if name not in PROVIDERS:
+        if not cls._init:
+            from .interface.torch import TorchTransformer
+
+            cls._providers["torch"] = TorchTransformer
+
+            cls._init = True
+
+        if name not in cls._providers:
             raise NotImplementedError(f"Unsupported interface: {name}")
-        return PROVIDERS[name]
+        return cls._providers[name]