fix type errors (#3928)

* fix type checking error in overriding path propery

* fix type hints in sew stack

* enable type checking for tartan

* ignore type warnings for dynamic wx module attributes

* fix tartan type errors

* fix circular import

* add type-check and test targets

* use Optional instead

1 files changed, 50 insertions, 0 deletions

diff --git a/lib/sew_stack/stitch_layers/mixins/protocol.py b/lib/sew_stack/stitch_layers/mixins/protocol.py
new file mode 100644
index 00000000..1057bd7b
--- /dev/null
+++ b/lib/sew_stack/stitch_layers/mixins/protocol.py
@@ -0,0 +1,50 @@
+from typing import Protocol, TYPE_CHECKING
+
+from lib.utils import DotDict, Point
+
+
+if TYPE_CHECKING:
+    from lib.sew_stack import SewStack
+
+
+class LayerProtocol(Protocol):
+    paths: 'list[list[Point]]'
+    config: DotDict
+    element: 'SewStack'
+
+
+def with_protocol(protocol):
+    """Include a protocol in a Mixin only for type hinting.
+
+    Normally we'd use a protocol in a mixin to indicate that we
+    expect certain attributes to be available on self, as
+    described here:
+
+    https://mypy.readthedocs.io/en/stable/more_types.html#mixin-classes
+
+    However, for some reason type-checkers then _only_ allow use of
+    properties on self that are defined in the protocol.  For example,
+    this doesn't work:
+
+    class MyMixin:
+        def foo(self):
+            return "hi"
+
+        def bar(self: LayerProtocol):
+            thing = self.foo()
+            if self.config.baz == thing:
+                ...
+
+    This fails because mypy says that "self.foo()" references unknown
+    attribute "foo"... even though it's defined right there in MyMixin.
+    This feels a little weird, but that's how it works.
+
+    Instead, we do it like this:
+
+    class MyMixin(with_protocol(LayerProtocol)):
+        ...
+    """
+    if TYPE_CHECKING:
+        return protocol
+    else:
+        return object