Switch to keyword-only arguments for a bunch of internal methods

[simonw]

This is a good idea, and one that needs to happen before Datasette 1.0:

While you are adding features, would you be future-proofing your APIs if you switched over some arguments over to keyword-only arguments or would that be too disruptive?

Thinking out loud:

async def render_template( 
     self, templates, *, context=None, plugin_context=None, request=None, view_name=None 
): 

Originally posted by @jefftriplett in #1817 (comment)

[simonw]

Everything on https://docs.datasette.io/en/stable/internals.html that uses keyword arguments should do this I think.

[simonw]

A start:

diff --git a/datasette/utils/asgi.py b/datasette/utils/asgi.py
index 8a2fa060..41ade961 100644
--- a/datasette/utils/asgi.py
+++ b/datasette/utils/asgi.py
@@ -118,7 +118,7 @@ class Request:
         return dict(parse_qsl(body.decode("utf-8"), keep_blank_values=True))
 
     @classmethod
-    def fake(cls, path_with_query_string, method="GET", scheme="http", url_vars=None):
+    def fake(cls, path_with_query_string, *, method="GET", scheme="http", url_vars=None):
         """Useful for constructing Request objects for tests"""
         path, _, query_string = path_with_query_string.partition("?")
         scope = {
@@ -204,7 +204,7 @@ class AsgiWriter:
         )
 
 
-async def asgi_send_json(send, info, status=200, headers=None):
+async def asgi_send_json(send, info, *, status=200, headers=None):
     headers = headers or {}
     await asgi_send(
         send,
@@ -215,7 +215,7 @@ async def asgi_send_json(send, info, status=200, headers=None):
     )
 
 
-async def asgi_send_html(send, html, status=200, headers=None):
+async def asgi_send_html(send, html, *, status=200, headers=None):
     headers = headers or {}
     await asgi_send(
         send,
@@ -226,7 +226,7 @@ async def asgi_send_html(send, html, status=200, headers=None):
     )
 
 
-async def asgi_send_redirect(send, location, status=302):
+async def asgi_send_redirect(send, location, *, status=302):
     await asgi_send(
         send,
         "",
@@ -236,12 +236,12 @@ async def asgi_send_redirect(send, location, status=302):
     )
 
 
-async def asgi_send(send, content, status, headers=None, content_type="text/plain"):
+async def asgi_send(send, content, status, *, headers=None, content_type="text/plain"):
     await asgi_start(send, status, headers, content_type)
     await send({"type": "http.response.body", "body": content.encode("utf-8")})
 
 
-async def asgi_start(send, status, headers=None, content_type="text/plain"):
+async def asgi_start(send, status, *, headers=None, content_type="text/plain"):
     headers = headers or {}
     # Remove any existing content-type header
     headers = {k: v for k, v in headers.items() if k.lower() != "content-type"}
@@ -259,7 +259,7 @@ async def asgi_start(send, status, headers=None, content_type="text/plain"):
 
 
 async def asgi_send_file(
-    send, filepath, filename=None, content_type=None, chunk_size=4096, headers=None
+    send, filepath, filename=None, *, content_type=None, chunk_size=4096, headers=None
 ):
     headers = headers or {}
     if filename:
@@ -284,7 +284,7 @@ async def asgi_send_file(
             )
 
 
-def asgi_static(root_path, chunk_size=4096, headers=None, content_type=None):
+def asgi_static(root_path, *, chunk_size=4096, headers=None, content_type=None):
     root_path = Path(root_path)
 
     async def inner_static(request, send):
@@ -313,7 +313,7 @@ def asgi_static(root_path, chunk_size=4096, headers=None, content_type=None):
 
 
 class Response:
-    def __init__(self, body=None, status=200, headers=None, content_type="text/plain"):
+    def __init__(self, body=None, *, status=200, headers=None, content_type="text/plain"):
         self.body = body
         self.status = status
         self.headers = headers or {}
@@ -346,6 +346,7 @@ class Response:
         self,
         key,
         value="",
+        *,
         max_age=None,
         expires=None,
         path="/",
@@ -374,7 +375,7 @@ class Response:
         self._set_cookie_headers.append(cookie.output(header="").strip())
 
     @classmethod
-    def html(cls, body, status=200, headers=None):
+    def html(cls, body, *, status=200, headers=None):
         return cls(
             body,
             status=status,
@@ -383,7 +384,7 @@ class Response:
         )
 
     @classmethod
-    def text(cls, body, status=200, headers=None):
+    def text(cls, body, *, status=200, headers=None):
         return cls(
             str(body),
             status=status,
@@ -392,7 +393,7 @@ class Response:
         )
 
     @classmethod
-    def json(cls, body, status=200, headers=None, default=None):
+    def json(cls, body, *, status=200, headers=None, default=None):
         return cls(
             json.dumps(body, default=default),
             status=status,
@@ -401,7 +402,7 @@ class Response:
         )
 
     @classmethod
-    def redirect(cls, path, status=302, headers=None):
+    def redirect(cls, path, *, status=302, headers=None):
         headers = headers or {}
         headers["Location"] = path
         return cls("", status=status, headers=headers)
@@ -412,6 +413,7 @@ class AsgiFileDownload:
         self,
         filepath,
         filename=None,
+        *,
         content_type="application/octet-stream",
         headers=None,
     ):

diff --git a/datasette/app.py b/datasette/app.py
index 03d1dacc..4d4e5584 100644
--- a/datasette/app.py
+++ b/datasette/app.py
@@ -190,6 +190,7 @@ class Datasette:
     def __init__(
         self,
         files=None,
+        *,
         immutables=None,
         cache_headers=True,
         cors=False,

[simonw]

I'll do this in a PR.