query interactive fallback, improve guess_stats

my/core/stats.py

@@ -6,7 +6,7 @@ import importlib
 import inspect
 import sys
 import typing
-from typing import Optional
+from typing import Optional, Callable, Any, List, Iterator
 
 from .common import StatsFun, Stats, stat
 
@@ -24,23 +24,29 @@ def guess_stats(module_name: str) -> Optional[StatsFun]:
     return auto_stats
 
 
-def is_data_provider(fun) -> bool:
+def is_data_provider(fun: Any) -> bool:
     """
     1. returns iterable or something like that
     2. takes no arguments? (otherwise not callable by stats anyway?)
+    3. doesn't start with an underscore (those are probably helper functions?)
     """
     # todo maybe for 2 allow default arguments? not sure
     # one example which could benefit is my.pdfs
     if fun is None:
         return False
+    # probably a helper function?
+    if fun.__name__.startswith("_"):
+        return False
     # todo. uh.. very similar to what cachew is trying to do?
     try:
         sig = inspect.signature(fun)
     except ValueError:  # not a function?
         return False
 
-    if len(sig.parameters) > 0:
+    # has at least one argument without default values
+    if len(list(sig_required_params(sig))) > 0:
         return False
+
     return_type = sig.return_annotation
     return type_is_iterable(return_type)
 
@@ -65,6 +71,35 @@ def test_is_data_provider() -> None:
         return ['a', 'b', 'c']
     assert idp(has_return_type)
 
+    def _helper_func() -> Iterator[Any]:
+        yield 5
+    assert not idp(_helper_func)
+
+
+# return any parameters the user is required to provide - those which don't have default values
+def sig_required_params(sig: inspect.Signature) -> Iterator[inspect.Parameter]:
+    for param in sig.parameters.values():
+        if param.default == inspect.Parameter.empty:
+            yield param
+
+
+def test_sig_required_args() -> None:
+
+    def x() -> int:
+        return 5
+    assert len(list(sig_required_params(inspect.signature(x)))) == 0
+
+    def y(arg: int) -> int:
+        return arg
+    assert len(list(sig_required_params(inspect.signature(y)))) == 1
+
+    # from stats perspective, this should be treated as a data provider as well
+    # could be that the default value to the data provider is the 'default'
+    # path to use for inputs/a function to provide input data
+    def z(arg: int = 5) -> int:
+        return arg
+    assert len(list(sig_required_params(inspect.signature(z)))) == 0
+
 
 def type_is_iterable(type_spec) -> bool:
     if sys.version_info[1] < 8: