WIP: mypy plugin

ex.py

@@ -0,0 +1,14 @@
+from glom import glom
+from attr import dataclass
+from typing import TYPE_CHECKING
+
+if not TYPE_CHECKING:
+    reveal_type = print
+
+
+@dataclass
+class Person(object):
+    age: int
+
+person = Person(age=25)
+reveal_type(glom(person, 'age'))

glom/contrib/mypy.py

@@ -0,0 +1,24 @@
+from typing import Type
+
+from mypy.plugin import Plugin, FunctionContext
+from mypy.types import Type as MypyType
+
+
+class _GlomPlugin(Plugin):
+    def get_function_hook(self, fullname: str) -> MypyType:
+        if fullname == 'glom.core.glom':
+            def test(ctx: FunctionContext) -> MypyType:
+                print(ctx)
+                print(ctx.arg_types[0][0], ctx.arg_types[1][0])
+                print(ctx.arg_types[1][0].last_known_value.value)
+                return ctx.api.expr_checker.analyze_external_member_access(
+                    ctx.arg_types[1][0].last_known_value.value,
+                    ctx.arg_types[0][0],
+                    ctx.context,
+                )
+            return test
+        return None
+
+
+def plugin(version: str) -> Type[Plugin]:
+    return _GlomPlugin

mypy.ini

@@ -0,0 +1,22 @@
+[mypy]
+# mypy configurations: http://bit.ly/2zEl9WI
+
+# Plugins, includes custom:
+plugins =
+  glom.contrib.mypy
+
+allow_redefinition = False
+ignore_errors = False
+ignore_missing_imports = True
+implicit_reexport = True
+strict_optional = True
+strict_equality = True
+no_implicit_optional = True
+local_partial_types = True
+warn_no_return = True
+warn_unused_ignores = True
+warn_redundant_casts = True
+warn_unused_configs = True
+
+# We need this to debug `mypy` plugin:
+show_traceback = True

requirements.txt

@@ -6,3 +6,5 @@ pytest==4.1.1
 tox==3.7.0
 virtualenv==15.1.0
 PyYAML==3.13
+mypy==0.780
+pytest-mypy-plugins==1.2.0