[PYTHON] Avoid dangerous global variables in kwarg default values (#68)

python/triton/kernel.py

@@ -1,5 +1,7 @@
 import os
 import struct
+from typing import Optional, Dict, List
+
 import torch
 # C bindings
 import triton._C.libtriton.triton as _triton
@@ -33,14 +35,31 @@ def synchronize(device):
     dev_id = -1 if dev_id is None else dev_id
     _torch_utils.synchronize(dev_id)
 
-def read(path, kernel_names=[]):
+def read(path, kernel_names:Optional[List]=None):
+    if kernel_names is None:
+        kernel_names = []
     with open(path, 'r') as f:
         source = f.read()
         source = _triton.extract_kernels(source, kernel_names)
     return source
 
 class kernel:
-    def __init__(self, src, device, defines=dict(), num_warps=4, autotune_vals=[], autotune_key=[]):
+    def __init__(self,
+                 src,
+                 device,
+                 defines: Optional[Dict]=None,
+                 num_warps:int=4,
+                 autotune_vals:Optional[List]=None,
+                 autotune_key:Optional[List]=None):
+
+        if defines is None:
+            defines = {}
+        if autotune_vals is None:
+            autotune_vals = []
+        if autotune_key is None:
+            autotune_key = []
+
+
         # check if src is empty
         if src == '':
             raise ValueError('Kernel source code is empty')