fix: don't prefill or type widgets from i2's NotSet signature default

streamlitfront/base.py

@@ -14,7 +14,11 @@
 
 from streamlitfront.spec_maker import SpecMaker
 from streamlitfront.session_state import get_state, _SessionState
-from streamlitfront.util import func_name, build_element_factory
+from streamlitfront.util import (
+    func_name,
+    build_element_factory,
+    signature_defaults,
+)
 
 # --------------------- types/protocols/interfaces --------------------------------------
 
@@ -132,10 +136,11 @@ def dispatch_funcs(
 
 
 def infer_type(sig, name):
+    defaults = signature_defaults(sig)  # i2's NotSet sentinel is not a default
     if name in sig.annotations:
         return sig.annotations[name]
-    elif name in sig.defaults:
-        dflt = sig.defaults[name]
+    elif name in defaults:
+        dflt = defaults[name]
         if dflt is not None:
             return type(dflt)
     else:
@@ -189,6 +194,7 @@ def get_func_args_specs(
         element_factory_for_annot or _get_dflt_element_factory_for_annot()
     )
     sig = Sig(func)
+    defaults = signature_defaults(sig)  # i2's NotSet sentinel is not a default
     func_args_specs = {name: {} for name in sig.names}
     for name in sig.names:
         d = func_args_specs[name]
@@ -200,8 +206,8 @@ def get_func_args_specs(
             missing,
             dflt_element_factory,
         )
-        if name in sig.defaults:
-            dflt = sig.defaults[name]
+        if name in defaults:
+            dflt = defaults[name]
             if dflt is not None:
                 # TODO: type-to-element conditions must be in configs
                 if isinstance(dflt, (list, tuple, set)):

streamlitfront/page_funcs.py

@@ -10,7 +10,12 @@
     BasePageFunc,
     _get_dflt_element_factory_for_annot,
 )
-from streamlitfront.util import build_factory, Command, NodeGetter
+from streamlitfront.util import (
+    build_factory,
+    Command,
+    NodeGetter,
+    signature_defaults,
+)
 
 
 # TODO: Extract the page setup (view_title, etc.) and make it injectable.
@@ -30,6 +35,7 @@ def get_func_elements_commands(
         element_factory_for_annot or _get_dflt_element_factory_for_annot()
     )
     sig = Sig(func)
+    defaults = signature_defaults(sig)  # i2's NotSet sentinel is not a default
     NodeGetter(state["views"])
 
     func_args_specs = {name: {} for name in sig.names}
@@ -46,8 +52,8 @@ def get_func_elements_commands(
             dflt_element_factory,
         )
 
-        if name in sig.defaults:
-            dflt = sig.defaults[name]
+        if name in defaults:
+            dflt = defaults[name]
             if dflt is not None:
                 # TODO: type-to-element conditions must be in configs
                 if isinstance(dflt, (list, tuple, set)):
@@ -68,6 +74,7 @@ def get_func_args_specs(
         element_factory_for_annot or _get_dflt_element_factory_for_annot()
     )
     sig = Sig(func)
+    defaults = signature_defaults(sig)  # i2's NotSet sentinel is not a default
     func_args_specs = {name: {} for name in sig.names}
     for name in sig.names:
         d = func_args_specs[name]
@@ -79,8 +86,8 @@ def get_func_args_specs(
             missing,
             dflt_element_factory,
         )
-        if name in sig.defaults:
-            dflt = sig.defaults[name]
+        if name in defaults:
+            dflt = defaults[name]
             if dflt is not None:
                 # TODO: type-to-element conditions must be in configs
                 if isinstance(dflt, (list, tuple, set)):
@@ -127,6 +134,7 @@ def special_get_func_args_specs(
         element_factory_for_annot or _get_dflt_element_factory_for_annot()
     )
     sig = Sig(func)
+    defaults = signature_defaults(sig)  # i2's NotSet sentinel is not a default
     func_args_specs = {name: {} for name in sig.names}
     for name in sig.names:
         d = func_args_specs[name]
@@ -138,8 +146,8 @@ def special_get_func_args_specs(
             missing,
             dflt_element_factory,
         )
-        if name in sig.defaults:
-            dflt = sig.defaults[name]
+        if name in defaults:
+            dflt = defaults[name]
             if dflt is not None:
                 # TODO: type-to-element conditions must be in configs
                 if isinstance(dflt, (list, tuple, set)):

streamlitfront/tests/test_not_set_defaults.py

@@ -0,0 +1,39 @@
+"""``i2``'s ``NotSet`` sentinel in a signature means "required / no default".
+
+See i2mint/i2#48: once ``i2.FuncFactory`` shows ``NotSet`` defaults, widgets must not
+be prefilled with the sentinel, nor typed after it. These tests use
+``i2.deco.NotSet`` directly, so they pass with any i2 version.
+"""
+
+from i2 import Sig
+from i2.deco import NotSet
+
+from streamlitfront import base, page_funcs
+
+
+def foo(a: int, b, c: str = "hi", d=2):
+    return a, b, c, d
+
+
+# ``foo`` with ``NotSet`` defaults, as a re-landed i2#88 ``FuncFactory`` would show.
+# Defined separately since ``Sig.__call__`` sets ``__signature__`` in place.
+def foo_with_not_set(a: int = NotSet, b=NotSet, c: str = "hi", d=2):
+    return a, b, c, d
+
+
+def test_infer_type_ignores_not_set():
+    for name in "abcd":
+        assert base.infer_type(Sig(foo_with_not_set), name) is base.infer_type(
+            Sig(foo), name
+        )
+
+
+def test_func_args_specs_are_not_prefilled_with_not_set():
+    for get_specs in (
+        base.get_func_args_specs,
+        page_funcs.get_func_args_specs,
+        page_funcs.special_get_func_args_specs,
+    ):
+        assert get_specs(foo_with_not_set) == get_specs(foo)
+        _, factory_kwargs = get_specs(foo_with_not_set)["a"]["element_factory"]
+        assert "value" not in factory_kwargs

streamlitfront/util.py

@@ -6,6 +6,29 @@
 from i2.signatures import Sig, name_of_obj
 from i2._deprecated import Command as _Command
 
+try:
+    from i2 import is_not_set
+except ImportError:  # older i2: same sentinel, not exported from the root yet
+    from i2.deco import NotSet as _NotSet
+
+    def is_not_set(x) -> bool:
+        """Return True iff ``x`` is ``i2``'s ``NotSet`` sentinel."""
+        return x is _NotSet
+
+
+def signature_defaults(sig) -> dict:
+    """Return ``sig.defaults`` without the params whose default is ``i2``'s ``NotSet``.
+
+    ``NotSet`` in a signature means "no value given", not a real default, so a widget
+    must not be prefilled with it, nor typed after it.
+
+    >>> from i2.deco import NotSet
+    >>> def foo(a, b=NotSet, c=3): ...
+    >>> signature_defaults(Sig(foo))
+    {'c': 3}
+    """
+    return {k: v for k, v in sig.defaults.items() if not is_not_set(v)}
+
 
 # TODO: Consider using functools.partial (or subclass thereof) instead of Command
 class Command(_Command):