Features

PYAMLO extends standard YAML with powerful features for complex configurations, making it perfect for machine learning, data pipelines, and application configuration management.

Quick Reference

Special Tags

Syntax	Purpose	Example
include!	Include & merge files	include!: [base.yml, env.yml]
!include	Include single file at key	config: !include config.yml
!include_from	Include key from config	config: !include_from config.yml
!@	Instantiate Python objects	!@datetime.datetime 2023 1 1
!@$	Dynamic object creation	!@collections.$counter_type or !@$target_class
!import	Import Python modules	!import datetime.datetime
!env	Environment variables	!env {var: API_KEY, default: none}
!extend	Extend existing lists	items: !extend [4, 5, 6]
!patch	Replace dictionaries	config: !patch {debug: true}

Variable Expressions (${...})

Type	Operators	Example
References	. access	${app.name} v${app.version}
Math	+ - * / // % **	${workers * 2 + 1}
Bitwise	& \| ^ ~ << >>	${flags \| permissions}
Comparison	== != < <= > >= in	${env == 'production'}
Logical	and or not	${debug and verbose}
Conditional	if-else	${50 if prod else 10}

CLI Overrides

Override any configuration value from the command line using pyamlo. prefix:

# Basic overrides
python -m pyamlo config.yml pyamlo.app.name=MyApp pyamlo.debug=true

# Multiple files with overrides
python -m pyamlo base.yml prod.yml pyamlo.database.pool_size=20

# Special tags in overrides
python -m pyamlo config.yml 'pyamlo.items=!extend [4,5]' 'pyamlo.settings=!patch {"debug": true}'

Programmatic Usage

Control configuration loading in Python:

from pyamlo import load_config

# Manual overrides
config = load_config("config.yml", overrides=["pyamlo.app.name=MyApp"])

# Automatic CLI reading
config = load_config("config.yml", use_cli=True)

# Combined approach
config = load_config("config.yml", 
    overrides=["pyamlo.app.name=MyApp"],  # Manual overrides
    use_cli=True                         # Also read from sys.argv
)

Processing Order

Configuration values are processed in this order (later overrides earlier):

1. Include processing (per file)
2. Config file merging (left to right)
3. Manual overrides (via overrides parameter)
4. CLI overrides (via use_cli=True)
5. Variable resolution and object instantiation