Migrate to pyparsing 3.x and drop Python 2.7 support by alejandrorm · Pull Request #337 · chimpler/pyhocon

alejandrorm · 2026-01-13T07:03:07Z

Summary

This PR migrates pyhocon from pyparsing 2.x to pyparsing 3.x, updating all deprecated API calls to use PEP8-compliant naming conventions. As pyparsing 3.x requires Python 3.6.8+, this also removes Python 2.7 and EOL Python 3.x versions (3.4-3.6) support.

Motivation

Pyparsing 3.3.0+ now emits DeprecationWarning for old camelCase method names (e.g., parseString, setParseAction)
These deprecated names will be removed in future pyparsing versions, which would break pyhocon
Pyparsing 3.0 was released in August 2021 - this migration is overdue
Python 2.7 reached EOL in January 2020 and Python 3.4-3.6 are also EOL
This future-proofs pyhocon and aligns with modern Python conventions

Changes Made

Dependency Updates

✅ Updated pyparsing from >=2,<4 to >=3.0.0
✅ Dropped Python 2.7, 3.4, 3.5, 3.6 support
✅ Added Python 3.10, 3.11, 3.12, 3.13 support
✅ Minimum Python version: 3.7+

API Migrations (pyparsing 3.x)

Method Names (camelCase → snake_case):

parseString() → parse_string()
setParseAction() → set_parse_action()
setDefaultWhitespaceChars() → set_default_whitespace_chars()
replaceWith() → replace_with()

Parameter Names:

caseless= → case_insensitive=
escChar= → esc_char=
unquoteResults= → unquote_results=
parseAll= → parse_all=

Code Cleanup

✅ Removed basestring/unicode compatibility shims
✅ Removed urllib2 fallback (now uses urllib.request directly)
✅ Removed Python < 3.5 glob fallback
✅ Removed Python < 3.4 imp module usage (now uses importlib.util)
✅ Simplified string type handling (str instead of unicode)
✅ Net reduction: 120 lines of compatibility code removed

Files Modified

File	Changes
`setup.py`	Updated dependencies and Python version classifiers
`tox.ini`	Updated test environments (py37-py313)
`pyhocon/config_parser.py`	17+ pyparsing API updates + Python 2.x removal
`pyhocon/period_parser.py`	3 pyparsing API updates
`pyhocon/config_tree.py`	Python 2.x compatibility removal
`pyhocon/converter.py`	Python 2.x compatibility removal

Testing

✅ All 309 tests pass with pyparsing 3.3.1
✅ No deprecation warnings emitted
✅ CLI tool verified working (pyhocon command)
✅ Tested with Python 3.13.3
✅ No behavioral changes to the pyhocon API

Test Results

============================= test session starts ==============================
platform win32 -- Python 3.13.3, pytest-9.0.2, pluggy-1.6.0
collected 309 items

tests/test_config_parser.py ............................ [truncated]
tests/test_config_tree.py ..............................
tests/test_converter.py ............................
tests/test_periods.py ..................................
tests/test_tool.py ........

======================== 309 passed, 1 xfailed in 5.23s ========================

Breaking Changes ⚠️

This PR introduces breaking changes for end users:

What Breaks

❌ Python 2.7 is no longer supported
❌ Python 3.4, 3.5, 3.6 are no longer supported
❌ Users on older Python versions must upgrade to Python 3.7+
❌ Users must have pyparsing 3.0.0+ installed

What Doesn't Break

✅ The pyhocon API remains unchanged (e.g., ConfigFactory.parse_file() still works)
✅ All existing HOCON files continue to parse correctly
✅ No changes to configuration syntax or behavior
✅ 100% backward compatible for users on Python 3.7+

Migration Guide for Users

For Users on Python 3.7+

No code changes required. Simply update dependencies:

pip install --upgrade pyhocon

For Users on Python 2.7 or 3.4-3.6

You must upgrade Python first:

# Upgrade to Python 3.7 or later
# Then install pyhocon
pip install --upgrade pyhocon

Or pin to the last compatible version:

pip install 'pyhocon<0.3.62'  # Last version supporting Python 2.7/3.6

Release Notes Suggestion

Version: 0.4.0 (suggest major/minor bump due to breaking changes)

Breaking Changes

Dropped Python 2.7, 3.4, 3.5, 3.6 support
Minimum Python version is now 3.7
Minimum pyparsing version is now 3.0.0

Changes

Migrated to pyparsing 3.x with PEP8-compliant API
Removed Python 2.x compatibility code
Added support for Python 3.10, 3.11, 3.12, 3.13
Reduced codebase by 120 lines

Improvements

Future-proof against pyparsing deprecation warnings
Cleaner, more maintainable codebase
Aligned with modern Python conventions

Checklist

Additional Context

Pyparsing 3.0 Release: August 2021
Python 2.7 EOL: January 2020
Python 3.6 EOL: December 2021
Current pyparsing version: 3.3.1 (as of testing)

References

MOTIVATION ---------- Pyparsing 3.0 was released in 2021 and introduced PEP8-compliant naming conventions for all methods and parameters (camelCase → snake_case). While backward-compatible aliases were initially provided, pyparsing 3.3.0+ now emits DeprecationWarnings for old names, and they will be removed in future versions. This migration future-proofs pyhocon against breaking changes and aligns the codebase with modern Python conventions. Additionally, pyparsing 3.x requires Python 3.6.8+, allowing us to drop Python 2.7 compatibility code and simplify the codebase. HIGH-LEVEL CHANGES ------------------ 1. Updated pyparsing dependency from '>=2,<4' to '>=3.0.0' 2. Dropped Python 2.7, 3.4, 3.5, 3.6 support (now requires Python 3.7+) 3. Updated all pyparsing method calls to PEP8 snake_case names 4. Updated all pyparsing parameter names to PEP8 conventions 5. Removed Python 2.x compatibility shims (basestring, unicode, urllib2, etc.) 6. Added support for Python 3.10, 3.11, 3.12, 3.13 DETAILED CHANGES ---------------- ### setup.py - Changed: 'pyparsing~=2.0;python_version<"3.0"' and 'pyparsing>=2,<4;python_version>="3.0"' - To: 'pyparsing>=3.0.0' (unified version constraint) - Removed Python 2.7, 3.4, 3.5, 3.6 from classifiers - Added Python 3.10, 3.11, 3.12 to classifiers ### tox.ini - Changed: envlist = flake8, py{27,38,39,310,311,312} - To: envlist = flake8, py{37,38,39,310,311,312,313} ### pyhocon/config_parser.py **Import changes:** - replaceWith → replace_with **Method name changes (all occurrences):** - .parseString() → .parse_string() - .setParseAction() → .set_parse_action() - .setDefaultWhitespaceChars() → .set_default_whitespace_chars() **Parameter name changes (all occurrences):** - caseless=True → case_insensitive=True - escChar='\' → esc_char='\' - unquoteResults=False → unquote_results=False - parseAll=True → parse_all=True **Python 2.x compatibility removal:** - Removed try/except blocks for basestring/unicode definitions - Removed urllib2 fallback imports (now using urllib.request directly) - Removed Python < 3.5 glob fallback - Removed Python < 3.4 imp module fallback (now using importlib.util) - Changed unicode() calls to str() - Changed isinstance(x, unicode) to isinstance(x, str) - Updated all docstring type annotations: basestring → str ### pyhocon/period_parser.py **Method name changes:** - .parseString() → .parse_string() - .setParseAction() → .set_parse_action() **Parameter name changes:** - parseAll=True → parse_all=True ### pyhocon/config_tree.py **Python 2.x compatibility removal:** - Removed try/except block for basestring/unicode - Changed unicode() calls to str() - Changed ConfigUnquotedString parent class: unicode → str - Updated all docstring type annotations: basestring → str ### pyhocon/converter.py **Python 2.x compatibility removal:** - Removed try/except block for basestring/unicode - Changed isinstance(config, basestring) to isinstance(config, str) - Updated all docstring type annotations: basestring → str TESTING ------- All 309 existing tests pass successfully with pyparsing 3.3.1. No deprecation warnings are emitted when running the test suite. CLI tool (pyhocon) verified working with new pyparsing version. BACKWARD COMPATIBILITY ---------------------- This is a BREAKING CHANGE for users: - Python 2.7 and Python 3.4-3.6 are no longer supported - Users must upgrade to Python 3.7+ and pyparsing 3.0+ The pyhocon API itself remains unchanged - only internal implementation and minimum version requirements have changed. DOCUMENTATION ------------- Added PYPARSING_MIGRATION_PLAN.md documenting the complete migration strategy, including all API mappings and testing procedures. Added CLAUDE.md providing guidance for AI assistants working with this codebase. 🤖 Generated with [Claude Code](https://claude.com/claude-code) Co-Authored-By: Claude <noreply@anthropic.com>

alejandrorm and others added 2 commits January 12, 2026 22:43

remove extra documentation

37af24f

lbenka mentioned this pull request Jan 21, 2026

Fix DeprecationWarnings from pyparsing #338

Open

Provide feedback

Saved searches

Use saved searches to filter your results more quickly

Migrate to pyparsing 3.x and drop Python 2.7 support#337

Migrate to pyparsing 3.x and drop Python 2.7 support#337
alejandrorm wants to merge 2 commits intochimpler:masterfrom
alejandrorm:master

alejandrorm commented Jan 13, 2026

Uh oh!

Reviewers

Assignees

Labels

Projects

Milestone

Development

Uh oh!

1 participant

Conversation

alejandrorm commented Jan 13, 2026

Summary

Motivation

Changes Made

Dependency Updates

API Migrations (pyparsing 3.x)

Code Cleanup

Files Modified

Testing

Test Results

Breaking Changes ⚠️

What Breaks

What Doesn't Break

Migration Guide for Users

For Users on Python 3.7+

For Users on Python 2.7 or 3.4-3.6

Release Notes Suggestion

Breaking Changes

Changes

Improvements

Checklist

Additional Context

References

Uh oh!

Reviewers

Assignees

Labels

Projects

Milestone

Development

Uh oh!

1 participant