Add an interface to override pretty-printing behavior

metricflow-semantics/metricflow_semantics/mf_logging/pretty_formattable.py

@@ -0,0 +1,17 @@
+from __future__ import annotations
+
+from abc import ABC, abstractmethod
+from typing import Optional
+
+
+class MetricFlowPrettyFormattable(ABC):
+    """Changes behavior for pretty-formatting using `MetricFlowPrettyFormatter`.
+
+    This interface is pending updates to allow for additional configuration and structured return types.
+    """
+
+    @property
+    @abstractmethod
+    def pretty_format(self) -> Optional[str]:
+        """Return the pretty-formatted version of this object, or None if the default approach should be used."""
+        raise NotImplementedError

metricflow-semantics/metricflow_semantics/mf_logging/pretty_print.py

@@ -10,6 +10,7 @@
 from dsi_pydantic_shim import BaseModel
 
 from metricflow_semantics.mf_logging.formatting import indent
+from metricflow_semantics.mf_logging.pretty_formattable import MetricFlowPrettyFormattable
 
 logger = logging.getLogger(__name__)
 
@@ -27,7 +28,7 @@ def __init__(
     ) -> None:
         """See mf_pformat() for argument descriptions."""
         self._indent_prefix = indent_prefix
-        if max_line_length <= 0:
+        if not max_line_length > 0:
             raise ValueError(f"max_line_length must be > 0 as required by pprint.pformat(). Got {max_line_length}")
         self._max_line_width = max_line_length
         self._include_object_field_names = include_object_field_names
@@ -336,6 +337,10 @@ def _handle_any_obj(self, obj: Any, remaining_line_width: Optional[int]) -> str:
                 remaining_line_width=remaining_line_width,
             )
 
+        if isinstance(obj, MetricFlowPrettyFormattable):
+            if obj.pretty_format is not None:
+                return obj.pretty_format
+
         if is_dataclass(obj):
             # dataclasses.asdict() seems to exclude None fields, so doing this instead.
             mapping = {field.name: getattr(obj, field.name) for field in fields(obj)}

metricflow-semantics/tests_metricflow_semantics/collection_helpers/test_pretty_print.py

@@ -2,12 +2,16 @@
 
 import logging
 import textwrap
+from dataclasses import dataclass
+from typing import Optional
 
 from dbt_semantic_interfaces.implementations.elements.dimension import PydanticDimension
 from dbt_semantic_interfaces.type_enums import DimensionType
 from metricflow_semantics.mf_logging.formatting import indent
+from metricflow_semantics.mf_logging.pretty_formattable import MetricFlowPrettyFormattable
 from metricflow_semantics.mf_logging.pretty_print import mf_pformat, mf_pformat_many
 from metricflow_semantics.test_helpers.metric_time_dimension import MTD_SPEC_DAY
+from typing_extensions import override
 
 logger = logging.getLogger(__name__)
 
@@ -179,3 +183,19 @@ def test_pformat_many_with_strings() -> None:  # noqa: D103
         ).rstrip()
         == result
     )
+
+
+def test_custom_pretty_print() -> None:
+    """Check that `MetricFlowPrettyFormattable` can be used to override the result when using MF's pretty-printer."""
+
+    @dataclass(frozen=True)
+    class _ExampleDataclass(MetricFlowPrettyFormattable):
+        field_0: float
+
+        @property
+        @override
+        def pretty_format(self) -> Optional[str]:
+            """Only show 2 decimal points when pretty printing."""
+            return f"{self.__class__.__name__}({self.field_0:.2f})"
+
+    assert mf_pformat(_ExampleDataclass(1.2345)) == f"{_ExampleDataclass.__name__}(1.23)"