Implementation:Mlflow Mlflow Check Function Signatures

Knowledge Sources	Mlflow_Mlflow
Domains	CI, CodeQuality
Last Updated	2026-02-13 20:00 GMT

Overview

Detects backward-incompatible changes to public Python function signatures in pull requests by comparing AST-parsed signatures against the base branch.

Description

This script uses Python's ast module to parse function signatures from changed files and compare them against the base branch version. It enforces several backward-compatibility rules:

For positional and positional-only parameters:

• Parameters cannot be reordered, renamed, or removed.
• Adding required positional parameters is a breaking change.
• Adding optional positional parameters is allowed only at the end.
• Making an optional parameter required is a breaking change.

For keyword-only parameters (order-agnostic):

• Parameters cannot be renamed or removed.
• Making an optional parameter required is a breaking change.
• Adding a required keyword-only parameter is a breaking change; adding an optional one is allowed.

The script filters to only check public modules under mlflow/, skipping private modules (those starting with underscore) and private functions. It produces GitHub Actions-compatible warning annotations when running in CI, or plain text output for local use.

Key dataclasses include Parameter (representing a single function parameter with position, required status, and kind), Signature (grouping positional and keyword-only parameters), and Error (formatting violation output).

Usage

Run this script in CI to detect breaking API changes before merging pull requests. It can also be run locally to check for signature compatibility against a base branch.

Code Reference

Source Location

• Repository: Mlflow_Mlflow
• File: dev/check_function_signatures.py
• Lines: 1-382

Signature

@dataclass
class Error:
    file_path: Path
    line: int
    column: int
    lines: list[str]
    def format(self, github: bool = False) -> str: ...

@dataclass
class Parameter:
    name: str
    position: int | None
    is_required: bool
    is_positional_only: bool
    is_keyword_only: bool
    lineno: int
    col_offset: int

@dataclass
class Signature:
    positional: list[Parameter]
    keyword_only: list[Parameter]
    has_var_positional: bool
    has_var_keyword: bool

def parse_signature(args: ast.arguments) -> Signature: ...
def check_signature_compatibility(
    old_fn: ast.FunctionDef | ast.AsyncFunctionDef,
    new_fn: ast.FunctionDef | ast.AsyncFunctionDef,
) -> list[ParameterError]: ...
def compare_signatures(base_branch: str = "master") -> list[Error]: ...
def main() -> None: ...

Import

# Run from repository root
python dev/check_function_signatures.py

# Specify a custom base branch
python dev/check_function_signatures.py --base-branch main

I/O Contract

Inputs

Name	Type	Required	Description
--base-branch	str	No	Base branch to compare against (default: GITHUB_BASE_REF env var or "master")

Outputs

Name	Type	Description
Warnings	stdout	Breaking change warnings in GitHub Actions annotation format or plain text format

Usage Examples

Basic Usage

# Run locally against master branch
python dev/check_function_signatures.py

# Run against a specific base branch
python dev/check_function_signatures.py --base-branch release/2.0

# In GitHub Actions CI (uses GITHUB_BASE_REF automatically)
python dev/check_function_signatures.py

Related Pages

• Environment:Mlflow_Mlflow_Python_Runtime_Environment