Refactored formatting (#8191)

Refactored `formatting.py`. The same as
https://github.com/langchain-ai/langchain/pull/7961 #8098 #8099
formatting.py is in the root code folder. This creates the
`langchain.formatting: Formatting` group on the API Reference navigation
ToC, on the same level as Chains and Agents which is incorrect.

Refactoring:

- moved formatting.py content into utils/formatting.py
- I did not add the backwards compatibility ref in the original
formatting.py. It seems unnecessary.
---------

Co-authored-by: Bagatur <baskaryan@gmail.com>

libs/langchain/langchain/formatting.py

@@ -1,38 +1,4 @@
-"""Utilities for formatting strings."""
+"""DEPRECATED: Kept for backwards compatibility."""
-from string import Formatter
+from langchain.utils.formatting import StrictFormatter, formatter
-from typing import Any, List, Mapping, Sequence, Union
 
-
+__all__ = ["StrictFormatter", "formatter"]
-class StrictFormatter(Formatter):
-    """A subclass of formatter that checks for extra keys."""
-
-    def check_unused_args(
-        self,
-        used_args: Sequence[Union[int, str]],
-        args: Sequence,
-        kwargs: Mapping[str, Any],
-    ) -> None:
-        """Check to see if extra parameters are passed."""
-        extra = set(kwargs).difference(used_args)
-        if extra:
-            raise KeyError(extra)
-
-    def vformat(
-        self, format_string: str, args: Sequence, kwargs: Mapping[str, Any]
-    ) -> str:
-        """Check that no arguments are provided."""
-        if len(args) > 0:
-            raise ValueError(
-                "No arguments should be provided, "
-                "everything should be passed as keyword arguments."
-            )
-        return super().vformat(format_string, args, kwargs)
-
-    def validate_input_variables(
-        self, format_string: str, input_variables: List[str]
-    ) -> None:
-        dummy_inputs = {input_variable: "foo" for input_variable in input_variables}
-        super().format(format_string, **dummy_inputs)
-
-
-formatter = StrictFormatter()

libs/langchain/langchain/prompts/base.py

@@ -5,10 +5,10 @@ import warnings
 from abc import ABC
 from typing import Any, Callable, Dict, List, Set
 
-from langchain.formatting import formatter
 from langchain.schema import BasePromptTemplate
 from langchain.schema.messages import BaseMessage, HumanMessage
 from langchain.schema.prompt import PromptValue
+from langchain.utils import formatter
 
 
 def jinja2_formatter(template: str, **kwargs: Any) -> str:

libs/langchain/langchain/utils/__init__.py

@@ -5,6 +5,7 @@ These functions do not depend on any other langchain modules.
 """
 
 from langchain.utils.env import get_from_dict_or_env, get_from_env
+from langchain.utils.formatting import StrictFormatter, formatter
 from langchain.utils.math import cosine_similarity, cosine_similarity_top_k
 from langchain.utils.strings import comma_list, stringify_dict, stringify_value
 from langchain.utils.utils import (
@@ -17,10 +18,12 @@ from langchain.utils.utils import (
 )
 
 __all__ = [
+    "StrictFormatter",
     "check_package_version",
     "comma_list",
     "cosine_similarity",
     "cosine_similarity_top_k",
+    "formatter",
     "get_from_dict_or_env",
     "get_from_env",
     "get_pydantic_field_names",

libs/langchain/langchain/utils/formatting.py

@@ -0,0 +1,38 @@
+"""Utilities for formatting strings."""
+from string import Formatter
+from typing import Any, List, Mapping, Sequence, Union
+
+
+class StrictFormatter(Formatter):
+    """A subclass of formatter that checks for extra keys."""
+
+    def check_unused_args(
+        self,
+        used_args: Sequence[Union[int, str]],
+        args: Sequence,
+        kwargs: Mapping[str, Any],
+    ) -> None:
+        """Check to see if extra parameters are passed."""
+        extra = set(kwargs).difference(used_args)
+        if extra:
+            raise KeyError(extra)
+
+    def vformat(
+        self, format_string: str, args: Sequence, kwargs: Mapping[str, Any]
+    ) -> str:
+        """Check that no arguments are provided."""
+        if len(args) > 0:
+            raise ValueError(
+                "No arguments should be provided, "
+                "everything should be passed as keyword arguments."
+            )
+        return super().vformat(format_string, args, kwargs)
+
+    def validate_input_variables(
+        self, format_string: str, input_variables: List[str]
+    ) -> None:
+        dummy_inputs = {input_variable: "foo" for input_variable in input_variables}
+        super().format(format_string, **dummy_inputs)
+
+
+formatter = StrictFormatter()

libs/langchain/tests/unit_tests/test_formatting.py

@@ -1,7 +1,7 @@
 """Test formatting functionality."""
 import pytest
 
-from langchain.formatting import formatter
+from langchain.utils import formatter
 
 
 def test_valid_formatting() -> None: