Single Source of Truth (SSOT)

Single Source of Truth (SSOT)#

Single Source of Truth

“Information must be defined in exactly one location. All subsequent usages must reference or derive from this primary definition.”

Scope of Application

  • Data: Raw inputs remain immutable; outputs are derived programmatically.

  • Metadata: Versions and licenses reside in a single configuration.

  • Parameters: Algorithmic settings are defined centrally.

Integration with DRY

  • DRY targets procedural logic and behavior.

  • SSOT targets data and state.

  • Eliminates conflicting project states.

  • Guarantees computational reproducibility.

Core Rule

“State must be referenced or derived, never duplicated.”

Example: Project Metadata#

Duplicated State ❌
# pyproject.toml
version = "1.2.0"

# src/mypkgs/__init__.py
__version__ = "1.2.0"

# docs/conf.py
release = "1.2.0"

Version bumps require modifying three separate files. Desynchronization is highly probable.

SSOT ✔
# pyproject.toml
[project]
version = "1.2.0"

# src/mupkgs/__init__.py
from importlib.metadata import version
__version__ = version("my_package")

Defined once. Parsed dynamically. Impossible to desynchronize.

Content