Handle fields that clash with Python reserved keywords

Author: danielgtaylor

README.md

@@ -155,7 +155,7 @@ You can use it like so (enable async in the interactive shell first):
 EchoResponse(values=["hello", "hello"])
 
 >>> async for response in service.echo_stream(value="hello", extra_times=1)
-    print(response)
+        print(response)
 
 EchoStreamResponse(value="hello")
 EchoStreamResponse(value="hello")
@@ -296,13 +296,13 @@ $ pipenv run tests
   - [ ] Any support
   - [x] Enum strings
   - [ ] Well known types support (timestamp, duration, wrappers)
-  - [ ] Support different casing (orig vs. camel vs. others?)
+  - [x] Support different casing (orig vs. camel vs. others?)
 - [ ] Async service stubs
   - [x] Unary-unary
   - [x] Server streaming response
   - [ ] Client streaming request
 - [x] Renaming messages and fields to conform to Python name standards
-- [ ] Renaming clashes with language keywords and standard library top-level packages
+- [x] Renaming clashes with language keywords
 - [x] Python package
 - [x] Automate running tests
 - [ ] Cleanup!

betterproto/__init__.py

@@ -26,6 +26,8 @@
 import grpclib.const
 import stringcase
 
+from .casing import safe_snake_case
+
 # Proto 3 data types
 TYPE_ENUM = "enum"
 TYPE_BOOL = "bool"
@@ -642,7 +644,7 @@ def to_dict(self, casing: Casing = Casing.CAMEL) -> dict:
         for field in dataclasses.fields(self):
             meta = FieldMetadata.get(field)
             v = getattr(self, field.name)
-            cased_name = casing(field.name)
+            cased_name = casing(field.name).rstrip("_")
             if meta.proto_type == "message":
                 if isinstance(v, list):
                     # Convert each item.
@@ -686,7 +688,7 @@ def from_dict(self: T, value: dict) -> T:
         self._serialized_on_wire = True
         fields_by_name = {f.name: f for f in dataclasses.fields(self)}
         for key in value:
-            snake_cased = stringcase.snakecase(key)
+            snake_cased = safe_snake_case(key)
             if snake_cased in fields_by_name:
                 field = fields_by_name[snake_cased]
                 meta = FieldMetadata.get(field)

betterproto/casing.py

@@ -0,0 +1,41 @@
+import stringcase
+
+
+def safe_snake_case(value: str) -> str:
+    """Snake case a value taking into account Python keywords."""
+    value = stringcase.snakecase(value)
+    if value in [
+        "and",
+        "as",
+        "assert",
+        "break",
+        "class",
+        "continue",
+        "def",
+        "del",
+        "elif",
+        "else",
+        "except",
+        "finally",
+        "for",
+        "from",
+        "global",
+        "if",
+        "import",
+        "in",
+        "is",
+        "lambda",
+        "nonlocal",
+        "not",
+        "or",
+        "pass",
+        "raise",
+        "return",
+        "try",
+        "while",
+        "with",
+        "yield",
+    ]:
+        # https://www.python.org/dev/peps/pep-0008/#descriptive-naming-styles
+        value += "_"
+    return value

betterproto/plugin.py

@@ -27,6 +27,8 @@
     ServiceDescriptorProto,
 )
 
+from betterproto.casing import safe_snake_case
+
 
 def get_ref_type(package: str, imports: set, type_name: str) -> str:
     """
@@ -255,7 +257,7 @@ def generate_code(request, response):
                         data["properties"].append(
                             {
                                 "name": f.name,
-                                "py_name": stringcase.snakecase(f.name),
+                                "py_name": safe_snake_case(f.name),
                                 "number": f.number,
                                 "comment": get_comment(proto_file, path + [2, i]),
                                 "proto_type": int(f.type),

betterproto/tests/keywords.json

@@ -0,0 +1,5 @@
+{
+  "for": 1,
+  "with": 2,
+  "as": 3
+}

betterproto/tests/keywords.proto

@@ -0,0 +1,7 @@
+syntax = "proto3";
+
+message Test {
+  int32 for = 1;
+  int32 with = 2;
+  int32 as = 3;
+}