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core.errors.domain_error

src.core.errors.domain_error

Base domain error class for Railway-Oriented Programming.

DomainError is the abstract base class for ALL application errors. Domain errors represent business rule violations and validation failures. They flow through the system as data (Result types), not exceptions.

Architecture: - Base class for all error types (core, domain, infrastructure) - Does NOT inherit from Exception (not raised, returned in Result) - Uses dataclass inheritance (NOT Protocol/ABC) - Type-safe with Result[T, DomainError]

Usage

from src.core.errors import DomainError from src.core.enums import ErrorCode

@dataclass(frozen=True, slots=True, kw_only=True) class MyError(DomainError): pass # Inherits code, message, details

Classes

DomainError dataclass

Base domain error (does NOT inherit from Exception).

Domain errors represent business rule violations and validation failures. They flow through the system as data (Result types), not exceptions.

Attributes:

Name Type Description
code ErrorCode

Machine-readable error code (enum).
message str

Human-readable error message.
details dict[str, str] | None

Optional context for debugging.
Source code in src/core/errors/domain_error.py 
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@dataclass(frozen=True, slots=True, kw_only=True)
class DomainError:
    """Base domain error (does NOT inherit from Exception).

    Domain errors represent business rule violations and validation failures.
    They flow through the system as data (Result types), not exceptions.

    Attributes:
        code: Machine-readable error code (enum).
        message: Human-readable error message.
        details: Optional context for debugging.
    """

    code: ErrorCode
    message: str
    details: dict[str, str] | None = None

    def __str__(self) -> str:
        """String representation of error."""
        return f"{self.code.value}: {self.message}"
Functions
__str__ 
__str__() -> str

String representation of error.

Source code in src/core/errors/domain_error.py 
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def __str__(self) -> str:
    """String representation of error."""
    return f"{self.code.value}: {self.message}"