Techdebt

Technical Debt Finder for DoubleML

Identify and fix technical debt aligned with project standards.

Project-Specific Checks

Type Annotations (MyPy Strict Mode)

• Missing type hints on functions (disallow_untyped_defs = true)
• Missing return type annotations
• Use of Any where specific types are possible
• Old-style typing (typing.List → list, typing.Dict → dict)
• Missing from __future__ import annotations for forward references

Docstrings (NumPy Style)

• Missing docstrings on public functions/classes
• Incorrect docstring format (must be NumPy-style)
• Missing Parameters, Returns, or Raises sections
• Outdated parameter documentation

Code Style (Black + Ruff)

• Lines exceeding 127 characters
• Import ordering issues (ruff rule I)
• Unused imports (ruff rule F401)
• Undefined names (ruff rule F821)
• Old-style string formatting (use f-strings)

Scikit-learn Compatibility

• Learners missing fit()/predict() interface
• Classifiers missing predict_proba() for propensity scores
• Missing clone() compatibility

DoubleML Patterns

• Inconsistent use of _check_learner() for validation
• Missing score function validation with _check_score()
• Incorrect sample splitting structure
• Missing psi_a/psi_b score elements

Workflow

1. Run Automated Checks

   # Type checking
   mypy doubleml
   
   # Linting
   ruff check .
   
   # Format check (dry-run)
   black --check .
   

2. Scan for Code Smells

   • Functions longer than 50 lines
   • More than 5 parameters
   • Deep nesting (> 3 levels)
   • Duplicate code blocks
   • Magic numbers without constants

3. Check for Dead Code

   • Unused imports
   • Unused functions/classes
   • Commented-out code blocks
   • Unreachable code paths

4. Report Findings Format: file_path:line_number - [severity] description

5. Fix Issues

   • Auto-fix with ruff check --fix .
   • Auto-format with black .
   • Manual fixes for type hints and docstrings

6. Verify

   ruff check .
   mypy doubleml
   pytest -m ci  # Run CI tests
   

Severity Levels

Arguments

Specify scope to focus the scan:

• /techdebt - Scan entire doubleml/ package
• /techdebt doubleml/plm/ - Scan PLM module
• /techdebt doubleml/utils/_checks.py - Scan specific file

Output Format

## Technical Debt Report

### High Severity
- `doubleml/plm/plr.py:45` - Missing return type annotation
- `doubleml/utils/_checks.py:123` - Type hint uses `typing.List`

### Medium Severity
- `doubleml/did/did.py:89` - Line exceeds 127 characters
- `doubleml/irm/irm.py:12` - Unused import `warnings`

### Low Severity
- `doubleml/double_ml.py:234` - Function has 67 lines (>50)
- `doubleml/utils/resampling.py:45` - Magic number `5` should be constant

### Fixed
- ✓ Auto-fixed 3 import ordering issues
- ✓ Auto-formatted 2 files with black

### Remaining
- 2 high severity items need manual fixes
- Consider refactoring `_nuisance_est()` in next session