Add type signature for a WSGI Application to wsgiref. #725

rowillia · 2016-11-30T18:49:43Z

This type is something core to Python and is useful when typing web applications,
but doesn't actually exist in the stdlib anywhere. I put this in wsgiref, but I am
open to suggestions as for a better place.

This type is something core to Python and is useful when typing web applications, but doesn't actually exist in the stdlib anywhere. I put this in wsgiref, but I am open to suggestions as for a better place.

ambv

I'm undecided here. At the same time, I see the need for specifying the application's (callable's) signature, and at the same time a more kosher place for it would be wsgiref/simple_server.pyi.

ambv · 2016-11-30T19:05:24Z

stdlib/2/wsgiref/__init__.pyi

@@ -0,0 +1,26 @@
+# Type declaration for a WSGI Function in Python 2
+#
+# This function actually exist, but we need a central place to define the type


I think you mean something along the lines of "WSGIFunction doesn't exist in wsgiref/init.py, it's a type provided for type checking purposes."

ambv · 2016-11-30T19:08:50Z

stdlib/2/wsgiref/__init__.pyi

+exc_info = Tuple[Optional[Type[BaseException]],
+                 Optional[BaseException],
+                 Optional[TracebackType]]
+WSGIFunction = Callable[[Dict[Union[unicode, str], Union[unicode, str]],


Wouldn't typing.AnyStr work better here?

@ambv no, AnyStr is a TypeVar and I don't want this function to be generic with respect to a single string type - https://github.com/python/typing/blob/master/python2/typing.py#L560 . It would be perfectly valid to have something like

environ = { u'hello': 'world' } result = app(environ, ....

ambv · 2016-11-30T19:10:07Z

stdlib/3/wsgiref/__init__.pyi

@@ -0,0 +1,26 @@
+# Type declaration for a WSGI Function in Python 3
+#
+# This function actually exist, but we need a central place to define the type


Ditto about the comment.

ambv · 2016-11-30T19:12:53Z

stdlib/2/wsgiref/__init__.pyi

+exc_info = Tuple[Optional[Type[BaseException]],
+                 Optional[BaseException],
+                 Optional[TracebackType]]
+WSGIFunction = Callable[[Dict[Union[unicode, str], Union[unicode, str]],


Also, this should rather be called WSGICallable as it can very well be a class, as documented in the comment in this example:
https://docs.python.org/3/library/wsgiref.html#examples

Or maybe WSGIApplication which it's called in most frameworks?

SGTM, will fix.

rowillia · 2016-11-30T20:06:30Z

@ambv Fixed up the names. I'd somewhat prefer to leave it under wsgiref as opposed to simple_server as it's core to WSGI, not just the simple_server and the ergonomics of:

if TYPE_CHECKING:
    from wsgiref.simple_server import WSGIApplication

Feels less authoritative than:

if TYPE_CHECKING:
    from wsgiref import WSGIApplication

ambv · 2016-11-30T21:37:40Z

Ssssh, I'm just trying to talk you into providing stubs for more files ;-)

ambv · 2016-11-30T23:26:44Z

@gvanrossum This looks reasonable to me, do you have an opinion?

gvanrossum · 2016-12-01T00:29:00Z

I'm not against having this alias in the wsgiref stubs per se, but:

exc_info probably should be renamed to _exc_info to clarify it is not part of the interface (it's a tuple type that's used anonymously in many places).
The __init__.py is currently empty; I think it should stay empty, and the type alias(es) should be in their own submodule. That's how the wsgiref package is structured.

rowillia · 2016-12-01T01:55:44Z

@gvanrossum moved things around. LMK what you think!

gvanrossum

Just various editorial nits. Also, do you have real-world code that uses this yet? It would be nice if you tested with that, to make sure that it's actually reasonable to write a function that conforms to the signature.

gvanrossum · 2016-12-01T02:24:29Z

stdlib/2/wsgiref/types.pyi

+# from typing import TYPE_CHECKING
+#
+# if TYPE_CHECKING:
+#   from wsgiref import WSGIFunction


Change to from wsgiref.types import ...

gvanrossum · 2016-12-01T02:24:43Z

stdlib/2/wsgiref/types.pyi

+# wsgiref/typing.py doesn't exist and neither does WSGIApplication, it's a type
+# provided for type checking purposes.
+#
+# To correctly use this type stub, utilize the `TYPE_CHECKING` flag in


utilize -> use

gvanrossum · 2016-12-01T02:25:09Z

stdlib/2/wsgiref/types.pyi

@@ -0,0 +1,26 @@
+# Type declaration for a WSGI Function in Python 2
+#
+# wsgiref/typing.py doesn't exist and neither does WSGIApplication, it's a type


typing -> types

gvanrossum · 2016-12-01T02:28:16Z

stdlib/3/wsgiref/types.pyi

+#
+# if TYPE_CHECKING:
+#   from wsgiref import WSGIFunction
+#


In the PY3 version (but not in the PY2 version) you should also tell users to use "forward reference" notation when using this (except in # type: comments). An example would be good.

gvanrossum · 2016-12-01T02:33:49Z

stdlib/2/wsgiref/types.pyi

+WSGIApplication = Callable[[Dict[Union[unicode, str], Union[unicode, str]],
+                            Union[
+                                Callable[[Union[unicode, str], List[Tuple[Union[unicode, str], Union[unicode, str]]]], Callable[[Union[unicode, str]], None]],
+                                Callable[[Union[unicode, str], List[Tuple[Union[unicode, str], Union[unicode, str]]], _exc_info], Callable[[Union[unicode, str]], None]]


This is pretty unreadable. Maybe you can clear it up a bit using some more type aliases? (An added benefit might be that there are fewer differences between PY2 and PY3.)

gvanrossum · 2016-12-13T23:05:06Z

@rowillia Do you have time to update this? (I couldn't get GitHub to let me edit the files else I would have done it myself. :-)

rowillia · 2016-12-20T01:00:10Z

@gvanrossum Looking into it now, thanks for the feedback.

gvanrossum · 2017-01-09T17:26:12Z

@rowillia Ping? Do you have any time to update? Or should I just close this?

gvanrossum · 2017-01-13T21:36:55Z

Superseded by #825.

Add type signature for a WSGI Application to wsgiref.

81431d2

This type is something core to Python and is useful when typing web applications, but doesn't actually exist in the stdlib anywhere. I put this in wsgiref, but I am open to suggestions as for a better place.

rowillia force-pushed the add_wsgi_application_stub branch from ce54f29 to 81431d2 Compare November 30, 2016 18:53

ambv reviewed Nov 30, 2016

View reviewed changes

s/WSGIFunction/WSGIApplication and fix up comments

ad7c4b3

Move WSGIAppliation to wsgiref.types

7f8b822

gvanrossum requested changes Dec 1, 2016

View reviewed changes

ambv force-pushed the master branch 10 times, most recently from 63ba0ab to 7853c26 Compare December 23, 2016 00:12

ambv mentioned this pull request Jan 12, 2017

Add type signature for a WSGI Application to wsgiref #825

Merged

gvanrossum closed this Jan 13, 2017

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Add type signature for a WSGI Application to wsgiref. #725

Add type signature for a WSGI Application to wsgiref. #725

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Add type signature for a WSGI Application to wsgiref. #725

Add type signature for a WSGI Application to wsgiref. #725

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rowillia commented Nov 30, 2016

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gvanrossum commented Dec 13, 2016

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