Give more useful errors for Fitters and Distributions

metasyn/distribution/base.py

@@ -52,6 +52,8 @@ class BaseFitter(ABC):
     plugin_version: str = "1.0"
 
     def __init__(self, privacy: BasePrivacy):
+        if not isinstance(privacy, BasePrivacy):
+            raise TypeError(f"To initialize fitter, supply a Privacy object, not {type(privacy)}.")
         self.privacy = privacy
 
     def fit(self, values: Union[npt.NDArray, pl.Series]) -> BaseDistribution:

metasyn/varspec.py

@@ -1,6 +1,8 @@
 """Module for distribution and variable specifications."""
 from __future__ import annotations
 
+import inspect
+
 # from metasyn.util import VarSpec
 from dataclasses import dataclass, field
 from typing import Any, Optional, Union
@@ -78,8 +80,12 @@ def parse(cls, dist_spec: Optional[Union[dict, type[BaseDistribution], BaseDistr
             return cls(**dist_spec)
         if isinstance(dist_spec, DistributionSpec):
             return dist_spec
-        if issubclass(dist_spec, BaseDistribution):
+        if inspect.isclass(dist_spec) and issubclass(dist_spec, BaseDistribution):
             return cls(name=dist_spec.name, unique=dist_spec.unique)
+        if (isinstance(dist_spec, BaseFitter)
+                or (inspect.isclass(dist_spec) and issubclass(dist_spec, BaseFitter))):
+            raise TypeError(f"Supplied Fitter {dist_spec}, but you should supply a distribution "
+                            "for parsing.")
         raise TypeError("Error parsing distribution specification of unknown type "
                         f"'{type(dist_spec)}' with value '{dist_spec}'")